LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 Class 
 
HAND-BOOK 
 
 TOR 
 
 HEATING AND VENTILATING 
 ENGINEERS 
 
 BY 
 
 s D. HOPPAXAN. n. E. 
 
 Professor of Engineering Design 
 Purdue University 
 
 ASSISTED BY 
 
 BENcJA/niN P. RABER, B.S.. A\.E, 
 
 Instructor In Engineering Design 
 Purdue University 
 
 LAPAYETTE, INDIANA 
 
^ 
 
 , v r> 
 
 \c 
 
 COPYRIGHT 1910 
 
 BY 
 JAMES D. HOFFMAN 
 
dr\Sr ^ 
 
 /^ Of THE 1 
 
 I UNIVERSITY J 
 Vfi 
 
 PREFACE 
 
 In the development of Heating and Ventilating work, it is 
 highly desirable that those engaged in the design and the 
 installation of the apparatus be provided with a hand-book 
 convenient for pocket use. Such a treatise should cover the 
 entire field of heating and ventilation in a simplified form 
 and should contain such tables as are commonly used in every 
 day practice. This book aims to fulfill such a need and is 
 Intended to supplement other more specialized works. 
 
 These contents have been compiled, in most part, from 
 lectures given to the Senior Mechanical Engineering class at 
 Purdue University during the past eight years. Most of this 
 material was issued in pamphlet form and used as a text 
 during the year 1909-10, with very satisfactory results. It 
 was thus possible to criticise and remove errors that would 
 otherwise have appeared in the finished book. Because of 
 the scope of the work, its various phases could not be dis- 
 cussed exhaustively, but it is believed that all the fundamen- 
 tal principles. are stated and applied in such a way as to be 
 easily understood. It is suggestive rather than digestive. 
 The principles presented are the same as those that have been 
 stated many times before, but the arrangement of the work, 
 the application and the designs are all original. Many for- 
 mulas and rules are necessarily given; but it will be seen that, 
 in most cases, they are developments from a few general 
 formulas, all of which can be readily understood and remem- 
 bered. Practical points in constructive design have also been 
 considered. However, since the principles of heating and 
 ventilation are founded upon fundamental thermodynamic 
 laws, it seems best to accentuate the theoretical side of the 
 work in the belief that if this is well understood, practical 
 points of experience will easily follow. Chapter 16 gives a 
 
 10 
 
suggested arrangement for a course of instruction that may 
 be used in technical schools. 
 
 It is hoped that the material here given will be simple 
 enough for the beginner and, at the same time, sufficiently 
 complete and exact for the engineer with years of experience. 
 If it merits the approval of the reader, or if any part is de- 
 fective or misleading, we trust that statements of approval 
 or criticism, as the case may be, will be freely contributed. 
 The only way to perfect such a book is to have the good 
 wishes and the co-operation of engineers in all branches of 
 the work. These are solicited. 
 
 All the standard works upon the subject have been freely 
 consulted and used. In most cases where extracts are made, 
 acknowledgment is given in the text. In addition to this, ref- 
 erences for continued reading are quoted at the close of each 
 important topic. Because of these references throughout 
 the book, we do not here repeat the names of their authors. 
 We wish, however, to express our sincere appreciation of 
 their valuable assitance. 
 LaFayette, Indiana. J, D. H. 
 
 September 1, 1910. B. F. R. 
 
CONTENTS 
 
 CHAPTER I. (Heat) 
 Arts. Pages 
 
 1- 4 Introductory. Measurement of Heat and 
 
 Temperatures 7- 11 
 
 5 Radiation, Conduction, Convection 12- 13 
 
 CHAPTER II. (Air) 
 6- 9 Composition of Air. Amount Required per 
 
 Person 14- 21 
 
 10- 13 Humidity 22- 27 
 
 14- 15 Convection of Air. Measurement of Air Ve- 
 locities 28- 31 
 
 16- 20 Air Used in Combustion. Chimneys 32- 33 
 
 References on Ventilation 34 
 
 CHAPTER III. (Heat Losses) 
 
 21- 29 Heat Losses from Buildings 35- 41 
 
 30 Temperatures to be Considered 41 
 
 31 Heat given off from Lights and Persons 43 
 
 References on Heat Losses from Buildings.. 44 
 
 CHAPTER IV. (Furnace Heating) 
 
 32- 34 Essentials of the B urnace System 45- 46 
 
 35- 37 Air Circulation in Furnace Heating 47- 49 
 
 38- 47 Calculations in Furnace Design 49- 51 
 
 48 Application to a Ten Room Residence 55- 59 
 
 CHAPTER V. (Furnace Heating, Continued) 
 
 49- 51 Selecting, Locating and Setting the Furnace. 60- 64 
 52- 57 Air Ducts. Circulation of Air in Rooms 64- 69 
 
 58 Fan-Furnace Heating 70 
 
 59 Suggestions for Operating Furnaces 70- 71 
 
 References on Furnace Heating 72 
 
 CHAPTER VI. (Hot Water and Steam Heating) 
 60- 65 Comparison and Classification of Systems.. 73- 78 
 66- 67 Vacuum Systems for Steam 79- 81 
 
 CHAPTER VII. (Ht. Water and St. Heating, Cont'd) 
 68- 73 Classification and Efficiencies of Radiators.. 82- 86 
 74- 77 Heaters and Boilers. Combination Systems. 
 
 Fittings 87- 92 
 
 CHAPTER VIII. (Ht. Water and St. Heating, Cont'd) 
 
 78- 80 Calculation of Radiator Surface 93- 99 
 
 81- 84 Pipe Sizes. Grate Area. Piping Connections. 99-102 
 85 General Application to Hot Water Design. .103-108 
 86- 87 Insulating Steam Pipes. Water Hammer 109-110 
 
 88 Feeding Return Water to Boiler 110-114 
 
 89 Suggestions for Operating Boilers 114-115 
 
 References on Hot Water and Steam Heating. 116 
 
 CHAPTER IX. (Mechanical Warm Air Heating) 
 90- 96 General Discussion. Blowers and Pans. 
 
 Heating Surfaces J.17-129 
 
 97- 99 Single and Double Duct Systems. Air Wash- 
 ing '. 129-132 
 
CHAPTER X. (Mech. Warm Air Heating, Cont'd) 
 
 100-104 Heat Loss. Air Required. Air Temper- 
 atures 133-135 
 
 105-106 Air Velocities. Area of Ducts 136-137 
 
 107-112 Heating Surface in Coils. Arrangement of 
 
 Coils 137-146 
 
 113-114 Amount of Steam Used in the System 146-147 
 
 CHAPTER XI. (Mecii. Warm Air Heating, Cont'd) 
 
 115-121 Air Velocity and Pressure. Horse Power in 
 
 Moving Air 148-156 
 
 122-124 Fan Drives. Speeds. Size of Engine. Piping 
 
 Connections 157-162 
 
 126 General Application to Plenum System 163-167 
 
 References on Mechanical Warm Air Heat- 
 ing 168 
 
 CHAPTER XII. (Mechanical Vacuum Heating) 
 
 127-131 General. Webster, Van Auken, Automatic 
 
 and Paul Systems 169-179 
 
 References on Mechanical Vacuum Heating. 180 
 
 CHAPTER XIII. (District Heating) 
 
 132-136 General. Conduits. Expansion Joints. 
 
 Anchors 181-192 
 
 137-139 Typical Design. Heat in Exhaust Steam. .193-199 
 140-143 Hot Water Systems. General Discussion. .. .200-202 
 144-146 Pressure and Velocity of Water in Mains. . .203-207 
 
 147-148 Radiation Heated by Exhaust Steam 207-208 
 
 149-157 Reheater Calculations 209-216 
 
 158-161 Circulating Pumps. Boiler Feed Pumps. .. .217-223 
 162-166 Radiation Supplied by Boilers and Economiz- 
 ers 223-227 
 
 167 Total Capacity of Boiler Plant 227-230 
 
 168-170 Cost of Heating from Central Station 230-235 
 
 171 Steam System. General Discussion 236-237 
 
 172-174 Pipe Sizes. Dripping the Mains 237-239 
 
 175 General Application of Steam System to Dis- 
 trict 239-241 
 
 References on District Heating 242 
 
 CHAPTER XIV. (Temperature Control) 
 
 176-179 General. Johnson, Powers and National Sys- 
 tems 243-252 
 
 CHAPTER XV. (Electrical Heating) 
 
 180-182 Discussion and Calculations 253-255 
 
 CHAPTER XVI. (Course of Instruction) 
 183-186 Outlines for Five Designs 256-262 
 
 CHAPTER XVII. (Specifications) 
 187 Suggestions on Planning Specifications 263-269 
 
 APPENDIX 
 Tables and Diagrams 271-315 
 
CHAPTER I. 
 
 HEAT ITS NATURE, GENERATION, USE, MEASUREMENT 
 AND TRANSMISSION. 
 
 1. Introductory: In all localities where the atmosphere 
 drops in temperature much below 60 degrees Fahrenheit, 
 there is created a demand for the artificial heating of build- 
 ings. As the buildings have grown in size and complexity 
 of construction, so also this demand has grown in extent 
 and preciseness, with the general result that from the 
 antiquated open fire-place and iron stove, there has developed 
 a science growing richer each day from inventive genius 
 and manufacturing technique the science of the Heating 
 and Ventilating- of Buildings. The purpose of this hand 
 book shall be to outline, concisely, the fundamental princi- 
 ples and practical applications of this science in its various 
 branches. 
 
 To the heating engineer of today, it may be that the 
 exact nature of heat itself is perhaps of less moment than 
 its generation and transmission, but this much should be 
 impressed, that heat is one form of energy, that it cannot 
 be created except by conversion from some other form, and 
 that it is infallibly obedient to certain physical laws and 
 principles. 
 
 In generating heat today for heating purposes, the 
 almost universal method is combustion. The union of such 
 substances as coal, wood or peat with the oxygen of the 
 air is always attended by a liberation of heat derived from 
 the chemical action of the combination; and this heat is 
 carried by some common carrier, such as air, water or 
 steam, to the building or room to be heated where it is 
 given off by the natural cooling process. In some instances 
 this heat is converted into electrical energy, which is car- 
 ried by wire to the place of use and given off by passing 
 through a set of resistance coils, which convert it into heat; 
 but this method is not much favored because of its inef- 
 ficiency and the resulting expense. This latter objection 
 
8 HEATING AND VENTILATION 
 
 would not hold in the case of water power installation, where 
 the combustion of fuel is entirely eliminated. 
 
 2. 3Ieasurement of Heat: In the measurement of heat, 
 the most commonly accepted unit in practical engineering 
 work is the British thermal unit, commonly abbreviated B. t. 
 u., which may be defined as that amount of heat which will 
 raise the temperature of one pound of pure water one de- 
 gree Fahrenheit, at or near the temperature of maximum 
 density, 39.1 F. This unit, the B. t. u., measures quantity 
 of heat, while the temperature measures the degree of heat. 
 In equal masses of the same substance the two are pro- 
 portional. The Fahrenheit is the more commonly used tem- 
 perature scale, especially in steam engineering. The 
 unit of this scale is derived by dividing the distance on the 
 thermometer between the freezing point and the boiling 
 point of water into 180 equal degrees, the freezing point be- 
 ing marked 32, and the boiling point 212. All temperatures 
 in this work will be taken according to the Fahrenheit scale, 
 and all quantities of heat expressed in British thermal units. 
 
 There is a second unit of quantity of heat considerably 
 used, especially in scientific research, known as the calorie, 
 commonly abbreviated cal., and defined as that amount of 
 heat which will raise one kilogram of pure water one de- 
 gree Centigrade, at or near the temperature of maximum 
 density, 4 C. This Centigrade is a second temperature 
 scale, the unit of which is derived by dividing the distance 
 on the thermometer between the freezing point and the 
 boiling point of water into 100 equal degrees, the freezing 
 point being marked 0, and the boiling point 100. 
 
 It is often found desirable to change the expression for 
 temperature or for quantity of heat from one system of 
 terms to that of the other. For this purpose the following 
 formulas will be found useful: 
 
 F=%C + S2 and C = ( .F-32) (1) 
 
 where F = Fahrenheit degrees and = Centigrade degrees. 
 From these equations it may be seen that the two scales co- 
 incide at but one point, 40 degrees. For conversion of the 
 quantity units the following may be used: 
 
 1 British thermal unit = 0.252 Calorie. 
 
 1 Calorie = 3.968 British thermal units. 
 
MEASUREMENT OF TEMPERATURE 
 
 These are for the absolute conversion of a certain quantity 
 of heat from one system to the other. If, however, the 
 effect of this heat is considered upon a given weight of 
 substance and the weight also is expressed in the respec- 
 tive systems, the following values hold: 
 
 1 Calorie per kilogram = 1.8 British thermal units per pound. 
 1 British thermal unit per pound = 0.555 Calorie per kilo- 
 gram. 
 
 For Conversion tables from kilograms to pounds and vice 
 versa, see Suplee's Mechanical Engineering Reference 
 Book, page 72, or Kent's Mechanical Engineers Pocket Book, 
 page 22. 
 
 3. 3Ieasurement of High Temperatures: For the meas- 
 urement of temperatures up to the boiling point of mer- 
 
 Fix. 1. 
 
 d. 
 
10 HEATING AND VENTILATION 
 
 cury, or approximately 600 P., the mercurial thermometer 
 of proper range may be employed. It is more common, 
 however, to use some form of pyrometer for temperatures 
 above 500 P., as when the temperatures of stack gases or 
 of fire box gases are desired. Pyrometers are built upon 
 many different principles, the graphite expansion stem type, 
 shown in Fig. 1, a; the thermo-electric type, shown in Fig. 
 1, b; or the Siemens water calorimeter type, shown in F ig. 1, c. 
 Various other methods might be mentioned, one of the best 
 being temperature determination by the Seger cones, which, 
 due to varying compositions, melt at different temperatures. 
 A line of these numbered cones is exposed to the sweep 
 of the gases to be measured, and their temperature de- 
 termined very closely by noting the number of the last 
 cone which melts. The cones are numbered from 022 to 39 
 and indicate temperatures from 590 to 1910 F., by ap- 
 proximate increments of 20. Fig. 1, d, shows cones 010, 09, 
 08 and 07, of which only the last is unaffected, and, from the 
 table furnished with the cones, this indicates a temperature 
 of 1000 F. 
 
 4. Absolute Temperature: In experiments that have 
 been carried on with pure gases with the use of air ther- 
 mometers, it has been found that air expands approximately 
 -j.^ of its volume per degree increase in temperature at 
 zero F. or _1- of its volume at zero C. From the same 
 line of reasoning, by cooling the air below zero, the reverse 
 process should be equally true, that is, for each degree 
 Fahrenheit of cooling the volume at zero would be contract- 
 ed i Evidently, then, if a volume of gas could be cooled 
 
 to 460 F., it would cease to exist. This theoretical point 
 is called the absolute zero of temperature. All gases change 
 to liquids or solids before this point is reached, however, and 
 hence do not obey the law of contraction of gases at the very 
 low temperatures. The fact that air at constant pressure 
 changes its volume almost exactly in proportion to the abso- 
 lute temperature, T, (460 + t, where t is temperature Fahren- 
 heit) gives a starting point to be used as a basis for all air 
 volume temperature calculations. For instance, if a volume 
 of 20000 cubic feet be taken in at the air intake of a build- 
 ing at 0, and heated to 70, its volume, by the heating, will 
 
ABSOLUTE TEMPERATURE AND PRESSURE 11 
 
 become greater in the same proportion that its absolute tem- 
 
 x 530 
 
 p.erature becomes greater; that is, =: ; x = 23000 
 
 20000 460 
 
 cubic feet, or an increase of 15 per cent. 
 
 GAGE AND ABSOLUTE PRESSURES. Two common ways of ex- 
 pressing pressures are in use. One is denoted by the expres- 
 sion pressure by gage, and refers to the total pressure in 
 a container minus the pressure of one atmosphere. Thus 
 the expression "65 pounds boiler pressure, by gage" means 
 that the boiler is carrying 65 pounds pressure, per square- 
 inch of surface, above the pressure of the atmosphere, which 
 is, for approximate calculations, taken at the standard pres- 
 sure of 14.696 pounds per square inch. Hence, the boiler 
 carries within it a total pressure of 65 pounds plus 14.696 
 pounds or 79.696 pounds per square inch. This total pres- 
 sure is what is known as absolute pressure, and when stated in 
 pounds per square foot of area, is called specific pressure. 
 Like the volume of a gas, so also the absolute pressure 
 varies directly with the absolute temperature/ other things 
 being constant. Hence the equation P V R T, where P 
 is the absolute pressure in pounds per square foot, V is the 
 volume of one pound in cubic feet, T is the absolute tem- 
 perature, and R is a constant which for air is 53.22. From 
 this equation, having given any two of the quantities, P, V 
 or T, the third may be found. In very accurate calculations 
 where the value 14.696 is not considered close enough, the 
 barometer may be read, and its readings, in inches of mer- 
 cury, multiplied by the constant .49, to obtain the pressure 
 of the atmosphere in pounds per square inch. 
 
 MECHANICAL EQUIVALENT OP HEAT. By precise experiment, it 
 has been determined that, if the heat energy represented by 
 one B. t. u. be changed into mechanical energy without loss, 
 it would accomplish 778 foot pounds of work. Similarly, 
 one calorie is equivalent to 428 kilogrammeters. One horse 
 power of work is equivalent to the expenditure of 33000 
 foot pounds of work per minute. Hence one horse power 
 of work represents 42.416 B. t. u. per minute. 
 
 LATENT HEAT. Not all the heat applied to a body pro- 
 duces change in temperature. Under certain conditions, the 
 heat applied produces internal or molecular changes, and is 
 called latent heat. Thus if heat is applied to ice at the freez- 
 ing point, no rise of temperature is noted until all the ice 
 
12 HEATING AND VENTILATION 
 
 is melted; and again, heat applied to water at boiling point 
 does not raise the temperature, but changes the water into 
 steam. The first is called latent heat of fusion, and for 
 ice is 142 B. t. u. per pound, while the latter is called latent 
 heat of evaporation, and for water is 969.7 B. t. u. per pound. 
 SPECIFIC HEAT. The ratio of the quantity of heat required 
 to raise the temperature of a substance one degree, to that 
 required to raise the temperature of water one degree from 
 the temperature of its maximum density, 39.1 degrees, is 
 commonly called the specific heat of the substance. Table 
 15, Appendix, gives 'specific heats of substances. 
 
 5. Radiation, Conduction and Convection: The trans- 
 mission of heat, next to its generation, forms an item of vital 
 interest to the heating engineer, for different forms of heat- 
 ing installations are based fundamentally on the different 
 ways in which heat is transmitted. These ways are usually 
 quoted as being three in number radiation, conduction and 
 convection. 
 
 RADIATION. This transmission of heat occurs as a wave 
 motion in the ether of space, and is the way by which the 
 heat of the sun reaches the earth. Heat of this form, usu- 
 ally referred to as radiant heat, requires no matter for its 
 conveyance, passes through some materials, notably rock- 
 salt, without change or appreciable loss, and travels, as does 
 light, at the rate of 186000 miles per second. 
 
 CONDUCTION. The second method of transmission is more 
 commonly evident to the senses. If a rod of metal is heat- 
 ed at one end, it is known that the heat is transferred, or 
 conducted, along the rod until the other end becomes heated 
 also. Conduction being, essentially, the way by which solids 
 transfer heat, is hence of special significance in the calcu- 
 lation of heat losses through the walls of a building. Rel- 
 ative conductivity of a substance may be defined as the 
 quantity of heat which passes through a unit thickness of 
 the substance in a unit of time across a unit of surface of 
 the substance, the difference of temperature between the 
 two sides of the substance being one unit of the thermo- 
 metric scale employed. Since the complexity of our build- 
 ing constructions renders it obviously impossible to reduce 
 all losses to losses per unit thickness of the structure, we 
 are not permitted to use the term relative conductivity but 
 another term, i. e., transmission constant, or rate of trans- 
 
HEAT TRANSMISSION 
 
 13 
 
 mission. Thus in Table IV, page 36, the rate of transmission K, 
 given for a 6 inch studded frame wall, is .25 B. t. u. per 
 square foot of surface per degree difference of temperature 
 for one hour. It is readily seen that this table is the basis 
 for the heat loss calculations of buildings. 
 
 CONVECTION. Gases and liquids convey heat 
 most readily by this method, which is funda- 
 mental with hot air and hot water heat- 
 ing installations. If it is attempted to heat 
 a body of water by applying heat to its up- 
 per surface, it will be found to warm up 
 I. ^ with extreme slowness. If, however, the 
 
 At _^r source of heat be applied below the body of 
 
 water as in Fig. 2, it will be found to heat 
 rapidly, the water being distributed by cir- 
 Fig. 2. culating currents having more or less force, 
 and following, in general, the direction shown 
 by the arrows. What actually happens is this: 
 water particles near the source of heat be- 
 come lighter, volume for volume, than the cold- 
 er particles near the top; then, because of the 
 change in density, gravity causes an exchange 
 of . these particles, drawing the heavier to the 
 bottom and allowing the heated and lighter 
 particles to rise to the top, thus forming the 
 circulation currents. This process is known as 
 convection. It will never occur unless the med- 
 ium expands considerably upon being heated, 
 and unless the force of gravity is free to es- 
 tablish circulating currents. The hot water 
 heating system may be considered merely as a 
 body of water, Fig. 3, furnished with proper pipe 
 circuits. When heated at one point, the 
 water rises by convection to the radiators, is 
 there cooled, hence becomes heavier, and de- 
 scends by the return circuit to the point of heat 
 application, thus completing the circuit. The warm air 
 furnace installation works similarly, air, however, being 
 the heat-carrying medium. 
 
 n 
 
 Fig. 3. 
 
CHAPTER n. 
 
 AIR COMPOSITION VENTILATION, HUMIDITY. 
 
 6. Composition of Atmospheric Air: The subject of 
 ventilation as applied to buildings would naturally be in- 
 troduced by a brief consideration of the properties of the 
 air supplied. This supply is a very important factor as re- 
 gards both quality and quantity. In addition to its value 
 as a heating medium, it determines, in a large measure, the 
 health of the occupants of the building. 
 
 The human body may be considered as a well equipped, 
 although very complex, power plant. As the carbon, hydro- 
 gen and oxygen in the fuel and air supply in any mechan- 
 ical power plant are consumed in the furnace, the resulting 
 heat absorbed in the generating system and finally turned 
 into work through the attached mechanisms, so the human 
 body in a similar way, but at a much slower rate, absorbs 
 the heat of combustion and turns it into work. The prod- 
 ucts of combustion in both cases are largely carbonic acid 
 and water. The chief requisites of the mechanical plant 
 are good fuel, good draft and good stoking. Similarly, the 
 human body needs pure food, pure air and healthful exer- 
 cise. Of the three, the second is probably of the greatest 
 importance, since no person can keep in health with im- 
 pure air, .even though accompanied with the best of food 
 and plenty of exercise. 
 
 Air, to the average person, is made up of two elements, 
 oxygen and nitrogen, in the volume ratio of about 20.9 to 
 79.1 and a density ratio of about 23.1 to 76.9, respectively. 
 We find in making a complete analysis of pure air, that a 
 number of other elements and compounds enter into it, mak- 
 ing a mechanical mixture which is somewhat complex. To 
 the heating and ventilating engineer, however, two im- 
 portant substances must be added to the two just stated, 
 and a revision of the percentages will therefore be neces- 
 sary. It may be said that pure air, as taken from the good 
 open country and not contaminated with poisonous gases 
 or the dust and refuse from the cities, would have about 
 
COMPOSITION OP AIR 15 
 
 the following composition. See Encyclopedia Britannica, 
 Respiration. 
 
 Oxygen Symbol O Per cent, of volume 20.26 
 
 Nitrogen " N " " " 78.00 
 
 Moisture " H 2 O " " " 1.7 
 
 Carbonic Acid " CO 2 " " " .04 
 
 These values are fairly constant, except that of the mois- 
 ture, which may vary according to the humidity anywhere 
 from + to 4 per cent, of the entire weight of the air. In 
 places where the air is not pure, the following substances 
 may be found in small quantities: Carbon Monoxide (CO), 
 Sulphuretted hydrogen (H 2 S), Ozone, Argon, compounds of 
 Ammonia, and compounds of Nitric, Nitrous, Sulphuric and 
 Sulphurous acids. 
 
 In the process of respiration, the lungs and the skin 
 of the average person will change the composition of the 
 air from that given above to 
 
 Oxygen Per cent, of volume 16 
 
 Nitrogen " " " 75 
 
 Moisture 5 
 
 Carbonic Acid " " " 4 
 
 Comparing these values with those for pure air, it will 
 be seen that the oxygen has been reduced about one-fifth, 
 the nitrogen has been reduced about one twenty-fifth, the 
 vapor has increased three times and the carbonic acid has 
 increased one hundred times. Oxygen has been consumed 
 in its uniting with the excess carbon and hydrogen in the 
 system, and is given off as carbonic acid and water vapor. 
 It may be seen from these ratios, that the very rapid increase 
 in carbonic acid (rejected bodily tissue), would soon render 
 unfit for use the air in almost any building occupied by a 
 number of people. To avoid this state of affairs, fresh air 
 should be supplied continuously and at such points as will 
 provide the most uniform circulation. 
 
 7. Oxygen and Nitrogen: The oxygen of the air fills 
 about one-fifth of the volume in atmospheric air and is the 
 element that makes combustion possible. The other four- 
 fifths of the space might be said to be filled with nitrogen. 
 In a providential way, this nitrogen acts as a sort of buffer 
 in its mixture with the oxygen and serves to control the 
 rapidity with which the combustion takes place. Nitrogen 
 seems to have little effect upon the respiration, except to 
 retard the chemical action between the oxygen and carbon 
 
16 HEATING AND VENTILATION 
 
 and the oxygen and hydrogen. If one were to attempt 
 to live in an atmosphere of pure oxygen, the chemical action 
 in the lungs would be so rapid that the human body would 
 not be able to maintain it. 
 
 8. Carbonic Acid: The amount of carbonic acid or 
 carbon dioxide as it is sometimes called, as found in the 
 air, is used as an index to the purity of the air. This is 
 not considered a poisonous gas. The real action of the car- 
 bonic acid when taken into the system is not well known. 
 It has the effect of producing physical depression, and 
 where fpund in sufficient quantity would even cause death. 
 Whatever its effect upon human life may be, its presence in 
 any room used for habitation i's usually an indication 
 of the lack of oxygen. Pure air has four parts carbonic 
 acid in 10000 parts of air, and room air should never be 
 allowed to have more than eight to ten parts in 10000 parts 
 of air. It becomes the problem of the heating engineer, 
 therefore, to provide air in sufficient quantities, and to enter 
 and withdraw the air from the room in a manner such as 
 will not be uncomfortable to the occupants, at the same 
 time keeping the air fairly uniform in quality, throughout 
 the room. Carbonic acid in the exhaled breath is about 
 five times heavier than air, and therefore, would have a 
 tendency to fall. It is exhaled, however, with excessive 
 moisture and at a temperature higher than that of the room 
 air, both qualities giving it a tendency to rise. These latter 
 factors probably neutralize the excessive density, and as 
 long as the air is not absolutely quiet, the result is a fair 
 diffusion throughout the room air. In large audiences the 
 heat given off from the occupants is sufficient to cause strong 
 air currents which, in rising, lift this impure air to the upper 
 part of the room. 
 
 A method of determining the percentage of carbon dioxide in the 
 air, based upon the fact that barium carbonate is nearly in- 
 soluble in water, may be performed as follows: Provide 
 eleven bottles with rubber stoppers having two holes each, 
 and connect them continuously by glass and rubber tubing, 
 so that if suction be applied at the first bottle of the series, 
 air will be drawn in at the last of the series and the same 
 air will be passed through all. In this way a sample of the 
 air to be tested may be drawn into each bottle. The capac- 
 ities of the bottles must be mad.e to be respectively, in 
 ounces, 23%, 18%, 16%, 14, 9%, 7%, 5%, 4, 3%, 2% and 2. 
 
DETERMINING THE PURITY OF AIR 
 
 17 
 
 This may readily be done by partially filling with parafflne. 
 Into each bottle is then placed % ounce of a 50 per cent, sat- 
 urated solution of barium hydrate, Ba(OH) 2 . More of the 
 air to be tested is drawn through the system until assurance 
 is had that each bottle contains a fair sample. Each bottle is 
 then thoroughly shaken, so that the liquid may be brought 
 into good contact with the air sample. If the least turbidity 
 or cloudiness appears in the 
 
 'First or largest bottle indicates 0.04 per cent. CO 2 
 
 Second bottle indicates 0,06 " " " 
 
 Third " " 0.07 " 
 
 Fourth " " 0.08 " 
 
 Fifth " " 0.10 " " " 
 
 Sixth " " 0.15 
 
 Seventh " " 0.20 " 
 
 Eighth 
 Ninth 
 Tenth 
 Eleventh 
 
 0.30 
 0.40 
 0.60 
 0.90 
 
 Care must be taken to have a fair sample of the air in 
 each bottle. The glass tubes through the rubber stoppers 
 should extend no farther than the bottom of the stoppers. 
 Fig. 4, a, shows four of the bottles and their connections. 
 
 As an example, suppose that the air of a room was tested 
 and that in the first, second, third, fourth, fifth and sixth 
 bottles the liquid became turbid after vigorous shaking. 
 Such room air would have contained 0.15 per cent, of carbon 
 dioxide, and would have been considered quite unfit for 
 breathing. 
 
 Fig. 4. 
 
18 HEATING AND VENTILATION 
 
 A second, less cumbersome, and, more delicate method of testing 
 for the percentage of carbon dioxide will be described, as it is 
 the method commonly used and only requires comparatively 
 simple apparatus, as shown in Fig. 4, (b). A bottle of 
 about 6 ounces capacity is fitted with a rubber stopper hav- 
 ing two holes. Through one hole a glass tube is brought 
 from the bottom of the bottle, and to the outer end of the 
 tube is connected a valved bulb similar to those found on 
 atomizers. Into the bottle are placed 10 cubic centimeters 
 of a, solution made by dissolving .53 grams of anhydrous 
 sodium carbonate, Na 2 CO 3 , in 5 liters of water, and adding 
 .01 gram of phenolphthalein. The water used must have been 
 previously boiled for at least one hour in an open vessel. 
 With the apparatus so prepared, squeeze the bulb, thus forc- 
 ing air from the room through the liquid and into the bot- 
 tle. The open hole in the rubber stopper is then closed with 
 the thumb, and the bottle shaken while, say, twenty is 
 counted, then another bulb-full of air is inserted, and again 
 shaken. This process is continued and the number of bulbs 
 of air noted until the red color of the solution, due to the 
 phenolphthalein, disappears. This number of bulb fillings is 
 indicative of the purity of the air according to the table 
 below. After such an apparatus is completed, it must be 
 calibrated before being used. This is done by testing the 
 number of bulb fillings of pure country air necessary to 
 clear the liquid, which will usually vary from 40 to 70. A 
 new table for that special apparatus is then obtained from 
 the one given below by proportion. In the table given, this 
 number of bulb fillings, with purest country air, is 48. If, 
 with the apparatus made up, it is found that, say, 60 bulb 
 fillings are required, then the proportionate table would be 
 made by multiplying the number of bulb fillings given below 
 by the ratio of 60 -r- 48, or 5 to 4. It is important that the 
 bulb be compressed the same amount for each filling, and 
 that the shaking of the bottle and contents be continued 
 the same length of time after each filling, to obtain uniform 
 results. 
 
DETERMINING THE PURITY OF AIR 19 
 
 TABLE I. 
 
 Fillings Per Cent CO 2 Fillings Per Cent CO a 
 
 48 .030 13 .08 
 
 40 .038 12 .083 
 
 35 .042 11 .087 
 
 30 .048 10 .09 
 
 28 .049 9 .10 
 
 26 .051 8 .115 
 
 24 .054 7 .135 
 
 22 .058 6 .155 
 
 20 .062 5 .18 
 
 19 .064 4 .21 
 
 18 .066 3 .25 
 
 17 .069 2 .30 
 
 16 .071 
 
 15 .074 
 
 14 .077 
 
 The methods outlined for the approximate estimation of 
 CO 2 are satisfactory for determining whether or not ventila- 
 ting systems maintain a proper degree of purity of air. If 
 exact percentages of CO, CO 2 , O and N are required, the Orsat 
 apparatus must be employed, for description of which see 
 Engineering Chemistry by Stillman, page 238. See also Car- 
 penter, H. & V. B., Chap. II, and Hempel's Gas Analysis, tran- 
 slated by Dennis. 
 
 9. Amount of Air Required per Person: The need of a 
 continuous supply of fresh air in our residence and business 
 houses can scarcely be over-estimated. Health is probably 
 the greatest of all blessings and pure air is absolutely es- 
 sential to health. The average adult, when engaged in or- 
 dinary indoor occupations, will exhale about twenty cubic 
 inches of air per respiration. He will also have sixteen to 
 twenty respirations per minute, making a total of 400 cubic 
 inches or, say, .25 cubic foot of air exhaled per minute. If 
 as in Art. 6, exhaled air contains 4 per cent. CO 2 , then 
 the average person will exhale 60 x .25 x .04 = .6 cubic foot 
 CO 2 per hour, (Pettenkofer, Smith & Parker), which is con- 
 stantly being diffused throughout the air of the room, thus 
 rendering it unfit for use. If this carbonic acid gas could 
 be disassociated from the rest of the air and expelled from 
 the room without taking large quantities of otherwise pure 
 air with it, the problems of the heating engineer would be 
 
20 HEATING AND VENTILATION 
 
 simplified, but this cannot be done. Because of this rapid 
 diffusion, it is necessary to flood the room with fresh 
 air in order that the purity may be maintained at a safe 
 value. The ideal conditions "would be to have it the same 
 as that of the outside air, but the mechanical difficulties 
 around such a ventilating 1 system would be so great as to 
 render it prohibitive. The standard of purity which should 
 be aimed at, and one, as well, which may be attained with a 
 first class system, is, .06 of one per cent. CO 2 , i. e., six parts 
 of CO 2 in 10000 parts of air. A system, however, which 
 maintains a standard of eight parts in 10000 would be 
 considered fairly satisfactory. This may be put in a simple 
 form for calculation. 
 
 Let Q L = cubic feet of atmospheric air needed per hour 
 per person; A = cubic feet of COa given off per hour per 
 person; n the standard of purity to be maintained (al- 
 lowable parts of COo in 10000 parts of air); and p = the 
 standard of purity in atmospheric air, say, 4; then 
 
 If we wish to maintain a purity in the room of seven 
 parts CO 3 in 10000 parts of air, and pure air contains four 
 parts in 10000, we have Qi = . 6 4- (.0007 .0004) = 2000 
 cubic feet of air per hour. 
 
 Another formula, quoted from Carpenter's Heating and 
 Ventilating of Buildings, very similar to the above, is 
 
 where a = the purity of the exhaled breath, say 400 parts 
 in 10000, n the purity to be maintained in the room and 
 6 = the cubic feet of air exhaled per minute. Substituting, 
 as above, 
 
 Q L = (400 X 60 X .25) -=- (7 4) = 2000 cubic feet. 
 
 Based upon .6 cubic foot of COs exhaled per person per 
 hour, Table II gives the amount of air needed to maintain 
 the various standards of purity. 
 
 It should be understood that no hard and fast rule can 
 be given for the air requirement per person. This, natur- 
 ally, would be a different amount when considering the 
 physical development for each person in health; it would 
 also be different for the same person according to his occu- 
 
AIR REQUIRED PER PERSON 21 
 
 pation at the time, sleep being the least, waking rest 
 somewhat greater, and physical exercise the greatest; but 
 it is decidedly varying when considering the state of the 
 person's health, or the sanitary value of his surroundings. 
 According as the degree of purity is demanded, the air 
 supply must be increased to suit it. 
 
 TABLE II. 
 Cubic F eet of Air per Person per Hour. 
 
 n 
 
 A 
 
 Qi 
 
 6 
 
 .6 
 
 3000 
 
 7 
 
 .6 
 
 2000 
 
 8 
 
 .6 
 
 1500 
 
 9 
 
 .6 
 
 1200 
 
 10 
 
 .G 
 
 1000 
 
 Generally, it is understood that the average adult sub- 
 jected to average conditions will require 1800 cubic feet of air 
 per hour. The amount of air needed for ventilation then in 
 most cases can be represented by the formula Q' = 1800 N, 
 wnere N = the number of people to be provided for. 
 
 The following table quoted from Carpenter's H. & V. B., 
 and from Morin in Encyclopedia Britannica, gives a fair 
 value for the amount of air per occupant per hour, that 
 should be supplied to rooms used for various purposes. 
 
 TABLE III. 
 
 Hospitals, Ordinary 2000-2400 cu. ft. per hour. 
 
 " Epidemic 5000 " " " " 
 
 Work Shops, Ordinary 2000 " " 
 
 Unhealthy trades ..3500 
 
 Prisons 1700 
 
 Theaters 1400-1700 " " 
 
 Meeting halls 1000-2000 
 
 Schools, per child 400- 500 " " 
 
 adult 800-1000 " " 
 
 Recent practice would tend to increase these values 
 somewhat; especially those relating to school bouse ventll- 
 
22 HEATING AND VENTILATION 
 
 ation, where a good estimate would be 800 to 1800 respec- 
 tively. 
 
 One ordinary gas burner of 20 candle power, using, say, 
 four cubic feet of gas per hour, will vitiate as much air 
 as three or four people. Where many lamps are used, this 
 fact should be taken into account. 
 
 In summing up the subject of ttie fresh air supply, it is well to call 
 attention to the fact that the ordinary running conditions of 
 any room cannot be absolutely determined by a single test for 
 carbon dioxide. Trials should be frequently made and rec- 
 ords kept. Upon one day the conditions may be unusually fav- 
 orable and would show a small amount of CO 2 even though a 
 very small amount of fresh air be admitted; while on other 
 days, when the conditions are not so favorable, a large 
 amount of fresh air would have to be supplied to maintain 
 the proper purity within. If the only requirement, therefore, 
 governing the ventilation of buildings should be that a satis- 
 factory CO 2 test be passed, there would be a large oppor- 
 tunity to overrate or underrate, as the case may be, the ven- 
 tilating system of the building. The only safe method in rating 
 ventilating systems is to require a minimum air supply in addition to a 
 maximum permissible percentage of C0 2 , 
 
 10. Moisture with Air: Moisture with the air is a benefit 
 to both the heating and ventilating systems in any room. 
 With moisture in the room, a person may feel comfortable 
 when the temperature is several degrees lower than the 
 comfortable temperature of dry air. Dry air takes up the 
 moisture from the skin. The vaporization of this moisture 
 causes a loss of heat from the body, and gives to the per- 
 son a sense of cold, which is only relieved when the tem- 
 perature of the room is increased. Air space that is fairly 
 saturated with moisture will not permit of much evaporation 
 from the skin, because there is not much demand for this 
 moisture with the air; consequently the body retains that 
 heat and the person has a sensation of warmth which is 
 only relieved by lowering the temperature of the air of the 
 room. On the other hand, at low temperatures the mois- 
 ture with air chills the surface of the skin by convection, 
 a condition that is not so noticeable when the air is dry. 
 It follows from the above statement that the range of com- 
 fortable temperatures is less for moist air than for dry air. 
 
 Concerning the effect of moisture in its relation to the 
 heating and ventilating of the room, we may say that thor- 
 
MEASUREMENT OF HUMIDITY 
 
 23 
 
 oughly dry air has not the quality of intercepting- radiant 
 heat; moisture, however, has this quality. Moist air has 
 also somewhat less weight than dry air and is more buoyant. 
 Because of the possibility of storing up the radiant heat 
 within the particles of moisture, and, because of its con- 
 vection qualities, it serves as a good heat carrier for the 
 heating system. 
 
 11. Humidity of the Airt The actual humidity is the 
 amount of moisture expressed in grains or in pounds per 
 cubic foot, mixed with the air at any temperature. The 
 relative humidity is the ratio of the amount of moisture actu- 
 ally with the air divided by the amount of moisture which 
 the same volume could hold at the same temperature when 
 saturated. It is very important that the heating engineer 
 be able to add to or to take away from the amount of the 
 moisture in the air supply of any building. To find the 
 amount of moisture that should be added or subtracted in 
 any case, it is first necessary to determine the humidity of 
 the air current at various points along its course. This 
 may be obtained by the aid of the wet and dry bulb ther- 
 mometer or by any one of a number 
 of hygrometers supplied by the 
 trade. The wet and dry bulb ther- 
 mometer has a very simple appli- 
 cation, and is probably in most gen- 
 eral use. The principle of its ap- 
 plication is as follows: having two 
 thermometers, Fig. 5, let one of 
 them register the temperature of 
 the room air, the other one being 
 kept wet by a cloth which covers 
 the bulb and projects into a vessel 
 filled with water, shown between 
 the two thermometers. If the air 
 Is saturated the two thermometers 
 will record the same temperature; 
 if, however, the air is not saturated 
 the thermometer readings will dif- 
 fer an amount depending upon the 
 Fig. 5. humidity. It will readily be seen that 
 
 the lowering of the temperature in 
 
 the wet thermometer is due to the extraction of the heat 
 in vaporizing the moisture from the bulb to the air. 
 
24 HEATING AND VENTILATION 
 
 In taking readings, let the mercury find a constant level 
 In each thermometer and then note the difference in temper- 
 ature between the two. In Table 10, Appendix, at this 
 difference and at the room temperature read off the relative 
 humidity; then take from Table 9, Appendix, the amount 
 of moisture with saturated air at the temperature recorded 
 by the dry thermometer, and multiply this by the humidity. 
 The result is the amount of moisture with the air per cubic 
 foot of volume. 
 
 APPLICATION. Room air, 70 degrees; difference in readings, 
 6 degrees. From Table 10, the humidity is 72 per cent. 
 From Table 9, col. 7, .72 X .001153 = .00083 pounds per 
 cubic foot. 
 
 To avoid the necessity for the use of tables, various in- 
 struments have been designed, which, graphically, give the 
 relative humidity directly. Fig. 6, shows such an instrument, 
 
 Fig. 
 
 commonly known as the Jiygrodeik. To find, by it, the relative 
 humidity in the atmosphere, swing the index hand to the 
 left of the chart, and adjust the sliding pointer to that de- 
 gree of the wet bulb thermometer scale at which the mer- 
 cury stands. Theoi swing the index hand to the right until 
 
MEASUREMENT OP HUMIDITY 25 
 
 the sliding pointer intersects the curved line which extends 
 downward to the left from the degree of the dry bulb 
 thermometer scale, indicated by the top of the mercury 
 column in the dry bulb tube. At that intersection, the in- 
 dex hand will point to the relative humidity on scale at bot- 
 tom of chart. Should the temperature indicated by the wet 
 bulb thermometer be 60 degrees and that of the dry bulb 
 70 degrees, the index hand will indicate humidity of 55 
 per cent., when the pointer rests on the intersecting line 
 of 60 degrees and 70 degrees. 
 
 For accurate work any instrument of the wet and dry bulb type 
 should be used in a current of air of not less than 15 feet per second. 
 
 12. For Close Approximation* and to avoid calculations, 
 the humidity chart, Fig. 7, may also be used in determining 
 relative humidity, absolute humidity, dew point, temperature 
 of wet bulb and temperature of dry bulb. On the left of the 
 chart is a scale referring to horizontal lines giving tempera- 
 tures of the wet bulb. The scale on the right hand, referring 
 to the lines curving downward from right to left, is the scale 
 of the room, or dry bulb, temperatures. The scale along the 
 bottom of the chart is one of relative humidity. The scale of 
 numbers up the center of the chart refers to the lines curving 
 downward from left to right, and indicates the absolute hu- 
 midity, i. e., grains of moisture per cubic foot with the air. 
 The use of the chart may be most readily understood by a 
 few applications. 
 
 APPLICATION. Given dry bulb 70 degrees and wet bulb 60 
 degrees. Determine relative humidity, absolute humidity, 
 temperature of dew point for room, etc. First, starting on 
 the right hand scale at 70, follow down the line this number 
 refers to until it crosses the horizontal line of 60 degrees, 
 wet bulb temperature. From this intersection drop to the 
 relative humidity scale and read there 55 per cent. This may 
 be checked with the table. To obtain the absolute humidity 
 will be noticed that the intersection of the 70 degree and 
 
 C- o o ><//' 5 i ? ~e- 5 -4" -4 
 
 degree-4+tt4s shows -8 grains per cubic foot. If the room 
 
 should cool, the absolute humidity would remain the same 
 until the dew point is reached (neglecting air contraction), 
 hence, following down the 8 Wrain line to 100 per cent, gives 
 the room temperature as ^*lr degrees, showing that if so 
 cooled the air would begin depositing moisture at this tem- 
 perature. Again if the room should heat to, say, 90 degrees, 
 the relative humidity may be obtained by following the -# 
 
26 
 
 HEATING AND VENTILATION 
 
 HYGROMETRIC CHART 
 
 OIVINO 
 
 HYGROMETER TEMPERATURES. RELATIVE HUMIDITY'. 'GRAINS OF MOISTURE PER CU. FT. 
 
 10 20 30 40 60 60 70 80-90 100 
 
 RELATIVE HUMIDITY IN t>ER CENT 
 
 Fig. 7. 
 
HUMIDIFYING THE AIR 27 
 
 <2*>ord t >i a<f 
 
 grain line to its intersection with the 90 degree^ line of 
 room temperature, and from this intersection dropping to the 
 relative humidity scale, and reading there 8*- per cent. Thus, 
 having given air under any set of conditions, the effect that 
 a change in any one of these would have upon the remaining 
 may be obtained without calculations. 
 
 13. The Theoretical Amount of Moisture to be Added to 
 Air ao as to Maintain a Certain Humidity: Warm air has a 
 much greater capacity for holding moisture than cold air. 
 According to the law of Gay-Lussac, when air is taken 
 at a given outside temperature and heated for interior 
 service, the volume increases with the absolute tempera- 
 ture. See Art. 4. On the other hand the humidity de- 
 creases rapidly. Air thus treated becomes dry and unpleas- 
 ant to the occupants, as well as being detrimental to the 
 furnishings of the room. Some means should, therefore, be 
 provided to supply this moisture to the air current. 
 
 In calculating the amount to be added, let Q = volume 
 of air in cubic feet per hour entering the room at the reg- 
 ister; t = its temperature in degrees and T = (460 + t) = 
 its absolute temperature; let Q' and Qo the correspond- 
 ing volumes after entering and before entering, with 
 t' and to the temperatures in degrees, and T' = (460 + V) 
 and To = (460 + to) the absolute temperatures; also, let u' 
 and Uo be the humidities, respectively, of the room air and 
 the outside air. Then, from the equations 
 
 TQ' = T'Q and TQ Q T Q (4) 
 
 find Q' and Q . 
 
 From Table 9, Appendix, find the amounts of moisture 
 Ai' and M in one cubic foot of saturated air at the temper- 
 atures t' and t ; multiply these by the respective humidities 
 and volumes, and the difference between the two final quan- 
 tities will be the amount of moisture required per hour as 
 expressed by the formula, 
 
 W = Q'M'u' Q Q M ii (5) 
 
 APPLICATION. Let Q 5000, t 130, t' 70, to = 30, u' 
 .50, u .50, M' 7.98, and Jf 1.958, then 
 Q' = 5000 X 530 -h 590 4490 
 Q 5000 X 490 -e- 590 = 4154 
 W = 13867 grains, or 1.984 pounds per hour. 
 This means that approximately 2 pounds of water would be 
 evaporated for every 5000 cubic feet of fresh air entering 
 the register under the above conditions. 
 
HEATING AND VENTILATION 
 
 14. Velocity in the Convection of Air by the Applica- 
 tion of Heat: Let 7; Fig. 8, be the height of the chimney 
 or stack. If the temperature of the gases 
 within the chimney CD be the same as that 
 of the entering air, then there will be no 
 natural circulation, because the column, CD, 
 will just balance a corresponding column 
 AB upon the outside; but if the temperature 
 of the chimney gases CD and entering air 
 4.B be tc degrees and to degrees, respectively, 
 the chimney gases being (tc -- to) degrees 
 greater than that of the outside air, then, 
 upon entering the chimney, the gases will 
 become less dense and expand an amount 
 proportional to the absolute temperature. 
 With an outside column of ho feet in height, 
 it will then require a column within, ho + ho 
 feet in height to produce equilibrium; in oth- 
 C er words, the column of gas producing mo- 
 tion in the chimney has a height of he feet. 
 Assume, in the system of ABCDE, that the 
 cross sections at all points be uniform, then the volumes of 
 AB (imaginary column) and CE (actual column) are to 
 each other as their respective heights, i. e., 
 Vo : To + V : :ho : ho + /c, and ho : 460 + to : : lio + ho : 460 -f tc 
 From this we obtain he (460 + to) = ho (tc to) and 
 
 Fig. 8. 
 
 ho (to to) 
 
 (6) 
 
 460 + to 
 
 Substituting for h in the equation v V2 yh, its correspond- 
 ing value he, we have 
 
 v = V 2ghe = 8.02 
 
 V 
 
 (tc to) 
 
 (7) 
 
 460 + to 
 
 It is found in practice that the theoretical velocity as 
 given by this formula is never obtained, because of the 
 friction of the sides of the chimney and other causes. Mr. 
 Alfred R. Wolff quoted the actual discharge from the chim- 
 ney as 50 per cent, of the theoretical. This estimate may 
 be fairly correct for chimneys of the larger sizes, but may 
 not be realized on the smaller ones used in residences. As 
 the transverse area becomes smaller, the percentage of fric- 
 tion increases very rapidly and soon becomes the principal 
 
MEASUREMENT OF AIR VELOCITIES 29 
 
 factor. Prof. Kent assumes a layer of gas two inches thick 
 next the interior surface as being ineffective. This, if ap- 
 plied to small cross-sectional areas, increases the size of 
 the chimney rapidly from the calculated amount. 
 
 When formula 7 is applied to hot air stacks in the 
 heating 1 systems, the friction is much less because of the 
 smooth interior, and the actual velocity of the air should 
 reach 60 to 70 per cent, of the theoretical. 
 
 15. Measurement of Air Velocities: See also Art. 115. 
 In ventilating work it is often of the greatest importance 
 to determine air velocities accurately. The correct deter- 
 mination of the sizes of air propelling fans or blowers 
 depends upon the ability to accurately measure the /velocity 
 of delivery. In acceptance and other tests this measurement 
 is equally important. However, no entirely satisfactory and 
 trustworthy method of obtaining this measurement has as 
 yet been devised. 
 
 The velocity of moving air is most commonly measured 
 by means of a vane w'heel instrument called the anemometer. 
 It consists essentially of a delicately pivoted wheel holding 
 from 6 to 15 vanes and similar to the common wind-mill 
 w.heel. See Fig. 9. To the shaft is connected a recording 
 mechanism of some sort, the simplest 
 being merely dials which show the 
 velocity of the air traveling past the 
 instrument, by the reading of which 
 against a stop-watch, the speed per 
 unit of time may be obtained. Since 
 the instrument works against the 
 friction of moving parts, its readings 
 are subject to serious variation, and 
 even with frequent calibration, it is 
 not to be relied upon where results 
 are required accurate to within 20 
 Fig. 9. per cent. Various tests of anemom- 
 
 eters by comparison to the absolute 
 
 readings of a gas tank have shown errors as high as 35 
 per cent, slow, to 14 per cent, fast, with the discharge from 
 pipes 8 inches to 24 inches in diameter. Hence, in general, 
 it is very safe to say that the anemometer as an instrument 
 for velocity measurement in precise work should be used 
 with great care. 
 
30 
 
 HEATING AND VENTILATION 
 
 A second method of velocity measurement, and on'3 
 applying as readily to liquids as to gases, is that of using- 
 the Pitot tube principle. Whenever, in a liquid or gas, a 
 pressure produces a flow, part of this pressure, usually 
 termed the velocity head, is considered as transformed into 
 velocity; while a second part, usually called the pressure 
 head, acts to produce pressure in the fluid. If now, as at 
 A, in Fig. 10, a tube be inserted into a pipe carrying a 
 
 B 
 
 Fig. 10. 
 
 current of air or other moving fluid, and the end of this 
 tube be bent so the plane of the opening is perpendicular 
 to the direction of the flow, a pressure in the tube will 
 result, due to both the velocity head and the pressure head; 
 and the difference in levels in the connected manometer 
 tube will indicate this sum of pressures in terms of inches 
 of water or mercury. If, however, a tube be inserted as at 
 B, with the plane of its opening parallel to the direction 
 of the flow, a pressure in the tube will result, due only 
 to the pressure head in the moving fluid; and the difference 
 in levels in the connected manometer tube will indicate this 
 pressure only. Then, by subtraction of the two manom- 
 eter readings, the velocity head only is obtained, expressed 
 in inches of water or mercury, whichever the manometer 
 may contain. 
 
 At C is shown the instrument as commonly applied, 
 with both tubes together and connected one to either leg 
 of the manometer tube so that the subtraction is automatic, 
 and the difference in levels read is caused by the velocity 
 only. Having, then, the head of pressure due to velocity, 
 to find the actual velocity apply the formula v = ^/2gJT where 
 v velocity in feet per second, g = acceleration of gravity 
 in feet per second, per second, and h = the velocity head 
 of the air in feet. If the manometer contains water, then, 
 
PITOT TUBE 31 
 
 at 60 degrees, the ratio between the specific gravity of air 
 
 62.37 
 
 and water is = 816.4. See Tables 9 and 6, Appendix. 
 
 .0764 
 
 Hence the above formula may be reduced to the more read- 
 ily available form of 
 
 v =.J 2 X 32.16 X 816.4 X , or 
 
 12 
 
 0= 66.2 V7^T~ (8) 
 
 where hw = the difference in height in inches of the columns 
 of a water manometer, with both legs connected as described, 
 and a temperature of 60 degrees. By a similar method the 
 formula may be reduced for a mercury or other manometer, 
 or for other temperatures than 60 degrees. 
 
 In using the Pitot tube or the anemometer, the fact 
 should not be lost sight of that the velocity varies from 
 a minimum at the inner walls of the tube to the maximum 
 at the center of the tube. It seems that the friction at the 
 inner walls throws the moving fluid into a number of 
 concentric layers, those toward the center moving the fast- 
 est, those toward the inner wall of the pipe the slowest. 
 With a circular tube, the variation of velocities of these 
 different layers may be approximately represented by the 
 abscissae of a parabola, Fig. 11, with its axis on the axis of 
 the circular pipe. Weisbach, on page 189 of his Mechanics of 
 
 Fig. 11. 
 
 Air Machinery, quotes the average speed at two-thirds of the 
 radius from the center, this value being obtained by ex- 
 periments. For conduits of other shapes the position of 
 mean velocity must be determined experimentally. This 
 variation of velocity from the center of the stream less- 
 
32 HEATING AND VENTILATION 
 
 ening toward the walls may possibly account for the vari- 
 ations shown by the anemometers. It is evident that 
 if such an instrument, with a given diameter of vane 
 wheel, be placed at the center of a pipe of large radius it 
 would tend to register a higher velocity than the average. 
 
 1C. Amount of Air Required to Burn Carbon: The chief 
 product in the combustion of carbon with the oxygen of the 
 air is CO^. The atomic weight of carbon is 12 and that 
 of oxygen is 16, hence the chemical union of the two form- 
 ing CO 2 is in the proportion of carbon 12 and oxygen 32 
 or as 1 : 2.66. For each pound of carbon consumed, 2.66 
 pounds of oxygen will be needed and the product will weigh 
 3.66 pounds. If pure air contains 23 per cent, oxygen, then 
 one pound of carbon will need 2.66 ~ .23 = 11.7, say 12 
 pounds of air for complete combustion. One cubic foot 
 of air at 32 degrees weighs .0807 pounds, then 12 -^- .0807 
 148 cubic feet of air necessary to burn one pound of car- 
 bon if all the oxygen of the air is burned. With volumes 
 proportional to the absolute temperatures, this air at 70 
 degrees would be 160 cubic feet; at 200 degrees, 200 cubic 
 feet; at 400 degrees, 260 cubic feet; and at 600 degrees, 320 
 cubic feet. 
 
 17. Probable Amount of Air Used: It seems reason- 
 able to assume, however, that in practice from two to 
 three times as much air goes through a furnace as would 
 be needed for perfect combustion. Taking this at, say, 2.5, 
 then the cubic feet of air found from tfce above would be 
 approximately: 32 degrees, 370 cubic feet; 70 degrees, 400 
 cubic feet; 200 degrees, 500 cubic feet; 400 degrees, 650 cubic 
 feet; and 600 degrees, 800 cubic feet. 
 
 IS. To Determine the Transverse Area of a Chimney 
 for Any Given Height: Substitute ho and the assumed 
 values of tc and to in formula 7, Art. 14. f rom this find 
 the velocity of the chimney gases, and divide the total 
 volume of air used in any given time, Art. 17, by the 
 corresponding velocity. 
 
 10. Application to the Chimney of a 10 Room Resi- 
 dence: Given: total heat loss from the building per hour, 
 100000 B. t. u.; coal 13500 B. t. u. per pound; furnace 
 efficiency, 60 per cent; temperature at bottom of chimney, 
 200 degrees F.; height of chimney, 30 feet above the grate; 
 average temperature of chimney gases, 150 degrees. (The 
 
CHIMNEYS. 33 
 
 greatest difficulty is experienced when the fire is first 
 started before the chimney is warmed up. The temperature 
 of the stack gases at such a time is very low.) Take the 
 outside air temperature, 40 degrees P., and find the size of 
 the chimney. 
 
 A heat loss of 100000 B. t. u. per hour will require 
 100000 -~ (13500 X .60) = 12.4 pounds of coal per hour at 
 the grate; then with a temperature of 200 degrees at the 
 bottom of the chimney, this will need to pass 500 X 12.4 = 
 6200 cubic feet of air per hour. The velocity of the chim- 
 ney gases, according to formula, is 20.5 feet per second or 
 73800 feet per hour. Assuming the real velocity to be, say, 
 25 per cent, of this amount, we have approximately 18450 
 feet per hour; then the net sectional area is 6200 -i- 18450 
 = .34 square foot or 49 square inches. To fit the brick 
 work this would probably be made 8 inches X 8 inches. 
 
 20. All Chimneys should have a Smooth Finish on the 
 Inside: Probably the best arrangement that can be made 
 is to build the chimney of hard burned brick around hard 
 burned tiles of suitable internal size. These tiles can be 
 had of outside sizes such that they can easily be made to 
 work in with the brick work. Table 12, Appendix, shows 
 chimney capacities that will be safe in average practice. 
 Flues should preferably be made round in section, as this 
 form presents less friction to the gases than any other. 
 B lues should never be built less than ten inches in diam- 
 eter, or eight by ten inches rectangular. The value of a 
 flue depends very much upon the volume of passage due 
 to area, and velocity due to height. Velocity alone is no 
 proof of good draft for there must also be sufficient area 
 to carry the smoke. The top of a chimney with reference 
 to its position relative to neighboring structures is a very 
 important consideration. If the top is below any nearby 
 portion of the building, eddy currents tending to enter the 
 top of the flue may be formed and seriously reduce the draft. 
 Under such conditions a shifting cowl, which always turns 
 the outlet away from adverse currents, may be advisable. 
 Good draft Is very essential to the success of any type of 
 heating system, and the purchaser of a furnace or heater 
 should be required to guarantee sufficient draft before a 
 maker is expected to guarantee a stated rating of his 
 furnace or heater. 
 
34 HEATING AND VENTILATION 
 
 REFERENCES. 
 
 References on Ventilation and the Air Supply. 
 
 TECHNICAL BOOKS. 
 
 Moore, The School House, p. 24. Monroe, Steam Heat. & Vent., 
 p. 99. Carpenter, Heat. & Vent. Bldgs., p. 21. Hubbard, Power, 
 Heat. & Vent., p. 408. Allen, Notes on Heat. & Vent., p. 91 
 Ency. Brit., Vol. XXIV, p. 157, also Vol. XX, p. 474. 
 
 TECHNICAL PERIODICALS. 
 
 Engr. Rev., Sanitation and Ventilation in Boston School 
 Houses, W. B. Snow, March, 1908, p. 15. Subway Ventilation, 
 J. B. Holbrook, Jan. 1905, p. 18. Ventilation of School Rooms, 
 Nov. 1905, p. 6. Heat. & Vent. Magazine. A Scotchman's Notes on 
 Ventilation, Alex. Mackenzie, May 1906, p. 15. Air Analysis as 
 an Aid to the Ventilating Engineer, J. R. Preston, Oct. 1906, p. 
 11. Domestic Engineering. Ventilation in its Relation to Health, 
 W. G. Snow, Vol. 52, No. 4, July 23, 1910, p. 102; Vol. 52, No. 6, 
 Aug. 6, 1910, p. 154. Ventilation of Isolated Offices, C. L. 
 Hubbard, Vol. 45, No. 10, Dec. 5, 1908, p. 274. Trans. A. S. H. 
 d V. E. The Necessity of Moisture in Heated Houses, R. C. Car- 
 penter, Vol. X, p. 129. Need of Ventilation in Heated Build- 
 ings, Vol. X, p. 183. Changing the Air in a Room, Vol. X. p. 
 285. Effect of Humidity on Heating Systems, Vol. IX, p. 323. 
 Necessity of Ventilation, H. Eisert, Vol. V. p. 57. The Engin- 
 eering Magazine. Humidifiers, Their Principles and Useful Ap- 
 plications, S. H. Bunnell, June 1910. The Heating, Ventilating 
 and Air Conditions of Factories. P. R. Moses, Aug. and 
 Sept. 1910. 
 
CHAPTER III. 
 
 HEAT LOSSES FROM BUILDINGS. 
 
 21. Loss of Heat by Conduction and Radiation: In 
 
 planning the heating system for any building, the first, and 
 probably the most important, part of the work is to esti- 
 mate the total heat loss per hour from the building. Un- 
 fortunately this is the part which is the least open to 
 satisfactory calculations and we find little valuable theo- 
 retical data upon the subject 
 
 Heat is lost from a building in two ways, by radiation 
 and by convection, i. e., that transferred through walls, win- 
 dows and other exposed surfaces by conduction and lost 
 by radiation; and that carried off by the movement of the 
 air as it passes out through the openings in the building 
 to the outside air. The radiation loss is usually of greater 
 importance, but the convection loss is of much more im- 
 portance than is generally considered. In the average 
 building both of these values are difficult to determine. 
 
 Radiation losses are considered under various heads, 
 such as glass, wall, floor, ceiling and door losses. Concern- 
 ing the conduction of heat through these various materials, 
 the available data have been obtained by experimentation 
 and do not agree very closely. Peclet in France, and Gras- 
 hof, Rietschel, Klinger and Rechnagel in Germany, each 
 carried on experimental research to determine the heat 
 transmission through various materials and structures. 
 These published data form the basis for a large part of the 
 heat loss calculations of the present time. Much valuable 
 material can be found in the more recent writings of 
 Hood, Wolff, Box, Carpenter, Kinealy, Allen, Hogan, Hub- 
 bard and others, but many of the values quoted are only 
 rough approximations at best. The reason for so much 
 uncertainty in this part of the work is found in the fact 
 that there are such great differences in methods of build- 
 ing construction. Conductivity tests for the various ma- 
 terials have been satisfactorily made, but when these same 
 materials have been put into a building wall the quality 
 of the workmanship often permits more heat loss by con- 
 
36 HEATING AND VENTILATION 
 
 vection than would be transmitted through the materials 
 themselves. The values quoted for brick walls and glass 
 agree fairly well. The greatest difficulty is found in the 
 balloon-framed building with its studded walls, where the 
 dead air space in a well constructed wall may be a good 
 non-conductor, or where, on the other hand, the same space 
 in a poorly constructed wall may become a circulating air 
 space to cool the walls by the movement of the air. 
 
 Table IV has been compiled from a number of the 
 best references as stated above, and represents a fair aver- 
 age of all of them. The value K (rate of transmission), in 
 some of the references, varied for the same material, being 
 somewhat greater for small temperature differences than 
 where the temperatures differed widely. Theoretically, the 
 transfer of heat through any substance is directly propor- 
 tional to the difference of the temperature between the two 
 sides of the substance. This was noticeably true for most 
 of the quotations. 
 
 TABLE IV. 
 
 Conductivities of Building Materials. 
 K = B. t. u. transmitted per sq. ft. per hour per degree dif. 
 
 Materials. K. 
 
 Brick Wall, 8", 4 
 
 Brick Wall, 12", .31 
 
 Brick Wall, 16", 26 
 
 Brick Wall, 20" 23 
 
 Brick Wall, 24", 21 
 
 Brick Wall 28", 19 
 
 Brick Wall, 32", 17 
 
 Brick Wall, Furred, use .7 times non-furred in each case. 
 Stone Wall, Use 1.5 times brick wall in each case. 
 
 Windows, Single Glass, 1.0 
 
 Windows, Double Glass, 6 
 
 Skylight, Single Glass, 1.1 
 
 Skylight, Double Glass, 7 
 
 Wooden Door, 1", 4 
 
 Wooden Door, 2", 36 
 
 Solid Plaster Partition, 2", 6 
 
 Solid Plaster Partition, 3", 6 
 
 Ordinary Stud Partition, Lath and Plaster on one side .6 
 
HEAT LOSSES FROM BUILDINGS 37 
 
 Ordinary Stud Partition, Lath and Plaster on two sides .34 
 
 Concrete Floor on Brick Arch, 2 
 
 Fireproof Construction as Flooring,. 1 
 
 Fireproof Construction as Ceiling, 14 
 
 Single Wood Floor on Brick Arch 15 
 
 Double Wood Floor, Plaster beneath, 10 
 
 Wooden Beams planked over, as Flooring, 17 
 
 Wooden Beams planked over, as Ceiling, 35 
 
 Walls of the Average Wooden Dwelling, 30 
 
 Lath and Plaster Ceiling, no floor above, 62 
 
 Lath and Plaster Ceiling, floor above, 25 
 
 Steel Ceilings, with floor above, 35 
 
 Single %" Floor, no plaster beneath, 45 
 
 Single %" Floor, Plaster beneath, 26 
 
 The following equivalents for doors, floors and ceilings 
 have been found to give good results: 
 
 Doors not protected by storm doors or vestibule = 200% of 
 equal wall area. 
 
 Floor over unheated space. Air circulation = same as wall. 
 Floor over unheated space. Still air = 40% of equal wall area. 
 Ceiling below unheated space. Air circulation = 125% of 
 equal wall area. 
 
 Ceiling below unheated space. Still air = 50% of equal wall 
 area. 
 
 In all references from French and German authorities, 
 one is impressed by the extreme care and exactness with 
 which every detail is worked out, even to those minor parts 
 usually considered in this country of no special moment. 
 
 22. Loss of Heat by Air Leakage: The exact amount 
 of air leaving a building by leakage is impossible to de- 
 termine. Many experiments have been carried on in the 
 last few years to determine the amount of leakage around 
 windows and doors. These in the specific cases have been 
 successful, but no actual values can be quoted for general 
 use. Again, a considerable amount of air passes through 
 the walls, thus rendering the case more complicated. In all 
 the experiments, however, it has been found that these 
 losses have been much greater than was supposed. In 
 rooms not heavily exposed, or in touch with heavy winds, 
 two changes per hour may be safely allowed for all leakage 
 losses. 
 
38 HEATING AND VENTILATION 
 
 23. Exposure Losses and Other Losses: Radiation 
 losses are much greater on the exposed or windward side of 
 the building. Moving air passing over the surface of any 
 radiating material will wipe the heat off faster than would 
 be true of still air. The north, north-west and the north- 
 east in most sections of the country get the highest winds 
 and have the least benefit of the sun and are therefore 
 counted the cold portions of the building. In figuring a 
 building it is customary to figure each room as though it 
 were a south room, which is assumed to need no additions 
 for exposure, and then add a certain percentage of this 
 loss for exposure to fit the location of the room. The exact 
 amount to add in each case is largely a matter of the judg- 
 ment of the designer, who, of course, is supposed to know 
 the direction of the heavy winds and the protection that 
 is afforded by surrounding buildings. A wide variety of 
 values covering the American practice might be quoted for 
 this, but the following will give satisfactory results: 
 
 TABLE V. 
 
 North, north-east and north-west rooms heavily exposed, 
 
 10-20 per cent. 
 
 East or west rooms moderately exposed,.... 5-10 per cent. 
 
 Rooms heated only periodically, 20-40 per cent. 
 
 The German practice is somewhat more extreme than 
 
 ours in this part of the work: 
 
 North, north-east and north-west rooms heavily exposed, 
 
 15-25 per cent. 
 
 East and west rooms, 10-15 per cent. 
 
 Surfaces exposed to heavy winds, 10-20 per cent. 
 
 Heat interrupted daily but rooms kept closed 10 per cent. 
 
 Heat interrupted daily but rooms kept opened 30 per cent. 
 
 Heat off for long periods 50 per cent. 
 
 Rooms 12 to 14% feet from floor to ceiling,.. 3 per cent. 
 
 Rooms 14% to 18 feet from floor to ceiling,.. 6 per cent. 
 
 Rooms 18 feet and above from floor to ceiling 10 per cent. 
 
 24. Loss of Heat by Ventilation: A certain amount of 
 fresh air leaks into every building and displaces an equal 
 amount of warm air, but this amount of fresh leakage air 
 is not considered sufficient for good ventilation. When 
 warm air is displaced either by leakage or by ventilation, 
 
ESTIMATION OF HEAT LOSS 39 
 
 it is exhausted to the outside air and as it leaves the room 
 carries a certain amount of heat with it. This is a direct 
 loss and should be taken into account. 
 
 Since the loss by leakage is practically the same for 
 all systems of heating, it is accounted for in the ordinary 
 heat loss formula, but losses by ventilating systems must 
 be considered in excess of this amount. Let Q' = cubic feet 
 of fresh air supplied per hour, V to = drop in temperature 
 from the inside to the outside air; then the heat lost by ex- 
 hausting the air, Art. 27, is 
 
 Q' ( t f to) 
 
 
 55 
 
 25. Two General Methods of Estimating the Heat Loss H 
 from a Building are in Common Use: First, estimate all 
 radiation losses and add to their sum a certain per cent. 
 of itself to allow for leakage by convection; second, esti- 
 mate all radiation losses and add to their sum a certain 
 amount which depends upon the volume of the room. The 
 first is by Equivalent Radiating Surfaces only and the second is 
 by Equivalent Radiating Surfaces and Volume combined. 
 
 26. Method No. 1: Figuring by Equivalent Radiating 
 Surface. Let H = R, t. u. heat loss from room per hour; 
 G = exposed glass in square feet; W = exposed wall minus 
 glass plus exposed doors reduced to equivalent wall surface 
 in square feet; F = floor or ceiling separating warm room 
 from unheated space; tx = difference between room temper- 
 ature and outside temperature; ty = difference between 
 room temperature and temperature of the unheated space; 
 K, K' and K" = coefficients of heat transmission; a = per- 
 centage allowed for exposure and & = percentage allowed 
 for loss by leakage, varying in per cent, of other losses 
 from 10 in the average house to 30 in the house of poor 
 construction. 
 
 From the above, we have 
 
 H = (KGt, + K'Wtm + K"Fty) (! + +&) (10) 
 
 APPLICATION. Assume the sitting room, Fig. 14, to have 
 a total exposed wall surface, W, exclusive of glass, 242 
 square feet; total exposed glass, (?, 38 square feet; and 
 
40 HEATING AND VENTILATION 
 
 floor, F, 195 square feet. Assume that all the rooms are 
 heated to 70 degrees with an outside temperature of zero 
 degrees and that all workmanship is fair. Assume also the 
 floor to be of the ordinary thickness and not ceiled below, with 
 a temperature below the floor of this room of 32 degrees; 
 and that two people are using the room. Under such con- 
 ditions what is the heat loss from the room? Since this 
 is a south room there is no exposure loss and = 0. Then 
 assuming 6 = .20 we have 
 
 H = (1 X 38 X 70 + .3 X 242 X 70 + .45 X 194X 38) (1 + .20) 
 = 13270 B. t. u. 
 
 27. Method No. 2: Figuring by Equivalent Radiating 
 Surface and Volume. The general formula for this is 
 
 H = (KGt* + K'Wt* + K"Ft v + ocnCfe) (1 + o) (11) 
 
 where H, K, O, tx, t v , W, F and a are as given above; C = cubic 
 volume of the room; n = number of times the air is sup- 
 posed to change in the room by leakage and convection per 
 
 hour, recommended, 1 to 2; oc = A- and is usually taken .02 
 
 55 
 for convenience of calculation. This constant refers to the 
 
 heat carried away by the air. The specific heat of the air 
 at 32 degrees is .238; then the number of pounds of air 
 heated from 32 to 33 degrees by 1 B. t. u. is 1 -T- .238 = 4.2. 
 Now if the weight of a cubic foot of air at 32 degrees is .0807 
 pounds, we would have 4.2 -T- .0807 = 52 cubic feet of air 
 heated from 32 to 33 degrees by 1 B. t. u. However, most 
 of the heating is not done at from 32 to 33 degrees but 
 from 32 to 70 degrees, in which case, the volume of air 
 heated from 69 to 70 degrees by 1 B. t. u. is 52 X 530 -^ 
 492 = 56 cubic feet. See absolute temperature, Art. 4. It 
 is evident that some approximation must here be made. No 
 exact value can be taken because of the great range of 
 temperature change of the air, but 55 is commonly used 
 as the best average. The difficulty of handling the formula 
 
 with the constant -=-=- has led to the simple form, .02. 
 
 55 
 
 APPLICATION. With the same room as used in Application 
 1, we have, if o = 0, 
 
 & = (1 X 38 X 70 + .3 X 242 X 70 + .45 X 195 X 38 + 
 .02 X 1 X 1950 X 70) (1 + 0) = 13806 B. t. u. 
 
ESTIMATION OF HEAT LOSS 41 
 
 28. Method No. 3: Professor Carpenter reviews the 
 work of the various authors and quotes the following 
 formula, which is the same as that given in Method No. 2 
 in a more simplified form, with the terms the same as 
 before: 
 
 H = (Gf + .25 W + .02 nC) t, (12) 
 
 In his opinion the very elaborate methods sometimes used 
 are unnecessary. K may be assumed .25 for any ordinary 
 wall surface, bricK or frame, and the ceilings adjoining an 
 attic or the floors above a cellar of the average house need 
 not be considered. Floors above an unexcavated space 
 where no heat is obtained from the furnace and where there 
 is more or less circulation of air should no doubt have 
 some allowance. This would probably be the same as given 
 in Art. 21. The values of n are quoted by the same author- 
 ity as follows: 
 
 Values of ro. 
 
 Residence Heating, Halls, 3; Sitting room and rooms on 
 the first floor, 2; Sleeping rooms and rooms on second 
 floor, 1. 
 
 Stores, First floor, 2 to 3; Second floor, 1^ to 2. 
 
 Offices, First floor, 2 to 2y 2 ', Second floor, 1% to 2. 
 
 Churches and Public Assembly rooms, % to 2. 
 
 Large rooms with small exposure, ^ to 1. 
 
 APPLICATION.- Assuming the same room as before, 
 H = [38 + .25 (242 + .4 X 195) + .02 X 2 X 1950] 70 = 13720. 
 
 29. Combined Heat Loss H' = (H + H v ) : In buildings 
 where ventilation is provided, the total heat loss is that lost 
 by radiation, H, + that lost by ventilation, Hr, (see also Art.. 
 36). Letting Qv = cubic feet of air needed per hour for 
 ventilation, we have, 
 
 Q v t* 
 
 H' = H H (13) 
 
 5 o 
 
 30. Temperatures to be Considered: The temperature 
 maintained in heated rooms in. this country is 70 degrees. 
 Outside temperatures used in figuring heat losses are gen- 
 erally taken, southern part, + 10 degrees; northern part 
 10 degrees; ordinary value, degrees. 
 
 The German Government requires estimates on the fol- 
 lowing temperatures, as quoted in "Formulas and Tables 
 for Heating," by Prof. J. H. Kinealy. 
 
42 HEATING AND VENTILATION 
 
 TABLE VI. Values of t'. 
 
 The temperatures of heated rooms are generally as- 
 sumed by the German Engineers to be as follows: 
 
 Rooms in which the occupants are for the most part at rest: 
 Living rooms, business rooms, court houses, offices, 
 
 schools 68 
 
 Lecture halls and auditoriums -..61 to 64 
 
 Rooms used only as sleeping rooms 54 to 59 
 
 Bath rooms in dwellings 68 to 72 
 
 Sick rooms 72 
 
 Rooms in which the occupants are undergoing bodily ex- 
 ertion:' 
 Workshops, gymnasiums, fencing halls, etc., in which 
 
 the exertion is vigorous 50 to 59 
 
 Workshops in which the exertion is not so vig- 
 orous 61 to 64 
 
 Rooms used as passage rooms or occupied by people in 
 street dress: 
 
 Entrance halls, passages, corridors, vestibules, 54 to 59 
 Churches , 50 to 54 
 
 Miscellaneous: 
 
 Prisons for the confinement of prisoners during 
 
 the day 64 
 
 Prisons for the confinement of prisoners during 
 
 the night 50 
 
 Hot houses 77 
 
 Cooling houses 59 
 
 Bath houses: 
 
 Swimming halls 68 
 
 Treatment rooms, massage rooms 77 
 
 Steam bath 113 
 
 Warm air bath 122 
 
 Hot air bath , ..140 
 
UNIVERSITY 
 
 """""tATION OF HEAT LOSS 43 
 
 TABLE VII. 
 Values of to When Applied to a Room. 
 
 The temperatures of rooms not heated are quoted 
 follows, with the outside air at 4 degrees below zero: 
 
 Cellars and rooms kept closed 32 
 
 Rooms often in communication with the outside air, 
 such as passages, entrance halls, vestibules, etc. 23 
 Attic rooms immediately beneath metal or slate 
 
 roof 14 
 
 Attic rooms immediately beneath tile, cement, or 
 tar and gravel roof 23 
 
 31. Heat given off From Lights and from Persons 
 "Within the Room: As a credit to the heating system, some 
 heating engineers take account of the heat radiated from 
 the lights and the persons within the room. The following- 
 table by Rubner is quoted by Prof. Kinealy: 
 
 TABLE VIII. 
 
 Gas, ordinary split burner, B. t. u. per candle power hr. 300 
 Gas, Argand burner, " " " " " " 200 
 
 Gas, Auer burner, " " " " " " 31 
 
 Petroleum, " " " " 160 
 
 Electric, Incandesc't " " " 14 
 
 Electric, Arc " " " " " 4.3 
 
 According to Pettenkofer, the mean amount of heat 
 given off per person per hour is 400 heat units for adults 
 and 200 for children. 
 
44 HEATING AND VENTILATION 
 
 REFERENCES. 
 
 References on Heat Losses and Radiation. 
 
 TECHNICAL BOOKS. . 
 
 iSnow, Principles of Heat., p. 54. Carpenter, Heading and 
 Ventilating Bldgs., p. 64. Hubbard, Power, Heat, and Vent., p. 417. 
 Allen, Notes on Heat, and Vent., p. 13. 
 
 TECHNICAL PERIODICALS. 
 
 Engineering Review. Air Leakage Around Windows; Its 
 Prevention and Effects on Radiation, Harold McGeorge, Feb. 
 1910, p. 64. The Heating and Ventilating Magazine. Austrian Co- 
 efficients for the Transmission of Heat through Building Ma- 
 terials, W. W. Macon, Feb. 1908, p. 36. Air Leakage through 
 Windows and its Effect Upon the AmJount of Radiation, B. 
 S. Harrison, Nov. 1907, p. 18. Air Leakage Around Windows 
 and its Prevention, H. W. Whitten, Dec. 1907, p. 20. Deriva- 
 tion of Constants for Building Losses. R. C. Carpenter, 
 March 1907, p. 34. Methods of Estimating Heat Losses from 
 Buildings, C. L. Hubbard, Sept. 1907, p. 1. Trans. A. S. H. & 
 V. E. Heat Losses and Heat Transmission, Walter Jones, 
 Vol. XII, p. 234. Loss of Heat through Walls of Buildings, 
 R. C. Carpenter, Vol. VIII, p. 94. 
 
CHAPTER IV. 
 
 FURNACE HEATING AND VENTILATING. 
 
 PRINCIPLES OF DESIGN. 
 
 32. Furnace Systems Compared with Other Systems: 
 
 The plan of heating residences and other small buildings 
 by furnace heat, in which the air serves as a heat carrier, is 
 a very common one in this country. Some of the points in 
 favor of the furnace system are: low cost of installation, 
 heating combined with ventilation, and the rapidity with 
 which the system responds to light service or to sudden 
 changes of outdoor temperatures. Compared with that of 
 other heating systems, the furnace system can be installed 
 for one-third to one-half the cost. In addition to this, the 
 fact that ventilation is so easily obtained, and the fact that 
 a small fire on a mild day may be sufficient to remove the 
 chill from all the rooms, give this method of heating many 
 advocates. The objections to the system are: cost of operation 
 when outside air is circulated, difficulty of heating the 
 windward side of the house, and the contamination of the 
 air supply by the fuel gases leaking through the joints in 
 the furnace. In a good system well installed, the only 
 objection to be seriously considered is the difficulty of heat- 
 ing that part of the house subjected to the pressure of the 
 heavy wind. The natural draft from a warm air furnace 
 is not very strong at best and any differential of pressure 
 in the various rooms will tend to force the air toward the 
 direction of least resistance. The cost of operating can be 
 controlled to the satisfaction of the owner consistent to his 
 ideas of the quality of the ventilation needed. Arrange- 
 ments may be made to carry the warm air from the room 
 back again to the furnace to be reheated, in which case, 
 if the fresh air be cut off entirely, the cost of heating is 
 about the same as that of any system of direct radiation 
 having no provision for ventilation. Any amount of fresh 
 air, however, may be taken from the outside for the pur- 
 pose of ventilation, thus requiring the same amount of air 
 
HEATING AND VENTILATION 
 
 to be exhausted at the room temperature and causing an 
 increased cost of operation, as discussed in Art. 36. 
 
 33. Essentials of the Furnace System: Fundamentally, 
 this installation must contain: first, a furnace upon proper 
 settings; second, a carefully designed and constructed sys- 
 tem of fresh air supply and return ducts; and third, the 
 warm air distributing leaders, stacks and registers. Fig. 
 12 shows, in elevation, a common arrangement of these 
 essentials, and gives, also, the air circulation by arrovv 
 
 directions. The installation shown is rendered flexible In 
 operation by the basement dampers, proper adjustment of 
 which will allow fresh air to be taken from either side 
 
FURNACE HEATING 47 
 
 of the house or furnished to the pit under the furnace by the 
 duct from the first floor rooms. This return register is 
 usually placed in the hall, under the stairway, or in some 
 room which is generally in open connection with the other 
 rooms on the first floor, as a large living room. 
 
 34. Points to foe Calculated in a Furnace Design: Be- 
 sides the calculated heat loss, H, which of course would 
 probably be the same for all methods of heating, other 
 points in furnace design would be taken up in the follow- 
 ing order: first, find the cubic feet of air needed as a 
 heat carrier and determine if this amount of air is sufficient 
 for ventilation; then calculate the areas of the following: 
 net heat register, gross heat register, heat stack, net 
 vent register, gross vent register, vent stack, leader pipes, 
 fresh air duct and total grate area. From the total grate 
 area the furnace may be selected. 
 
 35. Air Circulation in Furnace Heating: The use of air 
 
 in furnace heating may be considered from two standpoints, 
 each very distinct in itself. First, air as a Tieat carrier; 
 second, air as a Health preserver. The first may or may not 
 provide fresh air; it merely provides enough air to carry 
 the required amount of heat from the furnace to the rooms, 
 i. e., to take the place of the heat lost by radiation plus 
 the small amount that is carried away by the natural in- 
 terchange of air from within to without the building, as 
 would be true in any residence that is not especially planned 
 to provide ventilation. With certain allowable temperatures 
 at the various parts of the system, this volume of air may 
 be easily calculated. One' point here should be remembered: 
 when the cubic feet of air per hour as a heat carrier is 
 found at the register, this volume remains the same, no 
 matter if it enters the furnace through a duct from within 
 or without the building. So this plan may be both a heat 
 carrier and a ventilator if desired, subject only to the 
 amount of air required. The second plan requires that 
 enough air be sent to the rooms to provide ventilation. If 
 this amount is less than that needed as a heat carrier, all 
 well and good, the first amount will be used; but if it 
 should be greater, then the first amount will need to be 
 increased arbitrarily to agree. This increased volume will 
 then be used instead of that calculated as a heat carrier 
 
48 HEATING AND VENTILATION 
 
 only. As previously stated, the cubic feet of air per hour 
 as a ventilator may be taken as 1800 N, where N is the 
 number of persons to be provided for. See Art. 9. 
 
 36. Air Required per Hour as a Heat Carrier: A safe 
 temperature t, of the circulating air as it leaves the heat 
 register, is 130 degrees. This may at times reach 140 de- 
 grees but it is not well to use the higher value In the 
 calculations. If, as is nearly always the case, the room 
 air temperature, f, is 70 degrees, the incoming air will 
 drop in temperature through 60 degrees and, sin'ce one cubic 
 foot of air can be heated through 55 degrees by one B. t. u. 
 (see Art. 27.), it will give off 60 -H 55 = 1.09 (say 1.1) B. t. u. 
 
 Let Q = cubic feet of air per hour as a heat carrier; H 
 = total heat loss in B. t. u. per hour by formula; t = tern- 
 perature of the air at the register; and V temperature of 
 the room air; then 
 
 55 H 
 Q = (14) 
 
 t r 
 
 which for ordinary furnace work becomes 
 
 H 
 
 Q = 
 
 1.1 
 
 Now if this air is not allowed to escape from the building, 
 Fig. 12, but is taken back to the furnace and recirculated, 
 the only loss of heat will be H, that calculated by the 
 formula; but as a matter of fact, air thus used would soon 
 become contaminated and wholly unfit for the occupants to 
 breathe, hence, it is customary to exhaust through ventil- 
 ating flues, either a part or all of the air sent from the 
 furnace. This makes an additional loss of heat from 
 the building corresponding to the drop In degrees from 70 
 to that of the outside air. Let the temperature of the out- 
 side air, to, be degrees, then the resulting heat loss would 
 be (see also Art. 102 on blower work.) H' = H plus (t' to) 
 divided by 55 and multiplied by the amount of air intro- 
 duced for ventilation. Stated as a formula for the special 
 conditions, this becomes 
 
 H' = H -f 1.27 Qr (15) 
 
FURNACE HEATING 49 
 
 Take for illustration the Sitting Room, Fig. 14, and 
 consider it under three conditions on a zero day: first, when 
 all the air is recirculated; second, when only enough air is 
 exhausted to give good fresh air for ventilation; third, 
 when all the air is exhausted. Under the first case the loss 
 H, by formula is, say, 14000 B. t. u. per hour and no other 
 loss is experienced. In the second case, let three people oc- 
 cupy the room and allow 1800 cubic feet of fresh air per hour 
 for each person, or a total of 5400 cubic feet per hour, then 
 the total heat loss from the room will be, Formula 13, 
 14000 + 5400 X 70 -r- 55 = 20873, say 21000 B. t. u. The 
 third case, where all the air is exhausted, gives 14000 -4- 1.1 
 = 12727 cubic feet of fresh air exhausted at 70 degrees, 
 which requires the same amount of fresh air being raised 
 from zero to 70 degrees to replace it. This necessitates the 
 application of 12727 X 70 + 55 = 16198 B. t. u. additional, 
 or a total heat loss of 30198, say 30000 B. t. u. per hour. 
 
 The second condition is that which would be found most 
 satisfactory. It is evident from inspection that the cubic 
 feet of air necessary as a heat carrier will supply excessive 
 air for ventilation in the average residence, and the de- 
 signer need not necessarily consider the amount of air for 
 ventilation except as he wishes to investigate the size of 
 the furnace, the amount of coal burned or the cost of 
 heating; the latter being in direct proportion to the respect- 
 ive total heat losses. 
 
 APPLICATION. Referring to Table IX, page 56, the calcu- 
 lated amount of air per hour for the various rooms and for 
 the entire building may be found. 
 
 37. Is this Amount of Air Sufficient for Ventilation if 
 Taken from tae Outside? Take the 13 X 15 X 10 foot sitting 
 room, Fig. 14. Let the estimated heat loss be 14000 B. t. u. 
 per hour, then Q = 12727 cubic feet. With a room volume 
 of 1950 cubic feet, the air will change 6.5 times per hour, 
 and, allowing 1800 cubic feet of air per person, will supply 
 seven people with good ventilation if fresh air be used. 
 Stated as a formula, this would be 
 
 3 H 
 
 y = =: approx. (16) 
 
 1.1 X 1800 2000 
 
 As a matter of fact, ventilation for half this number would 
 
 be ample in an ordinary residence room excepting on extraor- 
 
50 HEATING AND VENTILATION 
 
 dinary occasions. So it would seem that the subject of 
 ventilating air will be more than taken care of if the ducts 
 and registers are planned to carry air for heating purposes 
 only. 
 
 38. Given the Heat Loss // and the Volume of Air Q r for 
 any Room, to find /, the Temperature of the Air Entering: at 
 the Register: If for any reason Q Is not sufficient for ven- 
 tilation, then more air must be sent to the room and the 
 temperature dropped correspondingly to avoid overheating 
 the room. Let Q f = total volume of air per hour, including 
 extra air for ventilation, measured at the register, then 
 
 55 H 
 
 t = 70 H (17) 
 
 Q' 
 
 APPLICATION. Suppose it were necessary to send 18000 
 cubic feet of fresh air to this sitting room per hour to ac- 
 commodate ten people, the temperature of the air at the 
 register should be 
 
 55 X 14000 
 
 t =s 70 + = 113. 
 
 18000 
 
 30. Net Heat Registers: The \elocity of the air v, 
 as it leaves the heat register, varies from 3 to 4 feet per 
 second according to different designers. The first figure 
 is objected to by some because it gives too large register 
 areas; while the latter value is claimed to be great enough 
 that the occupants of the room will notice the movement 
 of the air. Practice no doubt tends to the higher velocity. 
 Most heat registers in residences are placed at the floor 
 line. If, however, they be placed above the heads of the 
 occupants of the room (see Art. 94), higher velocities than 
 the ones named can be used. The general formula for net 
 registers is 
 
 IT X 55 X 144 
 
 N. H. R. = . (18) 
 
 (f f ) x v X 3600 
 
 Assuming a mean velocity of 3.5 feet per second, and 
 60 degrees drop in temperature from the register to the 
 room, then the square inches of net register for any room 
 are found by the formula: 
 
 H X 55 X 144 
 
 y. B. R. = = .01 H (19) 
 
 60 X 3.5 X 3600 
 
FURNACE HEATING 51 
 
 40. Net Vent Registers: Vent registers should be put 
 in with any furnace plant, although this is not always done. 
 In order that any room may be heated properly, it is abso- 
 lutely necessary that the cold air in the room be allowed 
 to escape to give room for the heated air to come in. This 
 in some cases is done by venting through doors, windows 
 or transoms. A tightly closed room cannot be properly 
 heated by a furnace. 
 
 If all the air were to pass out the vent register at the 
 same velocity as it entered through the heat register, the 
 area of the vent register would be to the area of the heat 
 register as the ratio of the absolute temperatures of the 
 leaving and entering air; that is, the area of the vent 
 register = .9 of the area of the heat register. As a matter 
 of fact since some of the air leaves the room through other 
 openings, the vent register need not be so large. Practice 
 has decided this area to be about 
 
 N. V. R. .008 H = .8 N. H. R. (20) 
 
 41. Gross Register Area: The nominal size, or catalog 
 size, of the register is usually stated as the two dimensions 
 of the rectangular opening into which it fits, and varies 
 from 1.5 to 2 times the net area. The larger value is prob- 
 ably the 'safer to follow unless the exact value be known 
 for any special make of register. 
 
 G. R. = (1.5 to 2) times the net register (21) 
 
 Round registers may be had if desired. Register sizes may 
 be found in Tables 14 and 17, Appendix. 
 
 42. Heat Stacks: To get the proper sizes of the stacks 
 in any heating system is a very important part of the de- 
 sign of that system. By some designers the cross sectional 
 area is taken roughly as a certain ratio to that of the net 
 register. This has been quoted anywhere from 50 to 90 
 per cent. Such wide variations between extremes of air 
 velocity should certainly require careful application. Prof. 
 Carpenter in H. and V. B. Arts. 54 and 141, suggests 4, 5 
 and 6 feet per second respectively, as the air velocities for 
 the first, second and third floors. Mr. J. P. Bird, in the 
 "Metal Worker" of Dec. 16, 1905, uses 280, 400 and 500 feet 
 per minute, which is approximately 4.5, 6.5 and 8 feet per 
 second under like conditions. The formula for cross sec- 
 
52 HEATING AND VENTILATION 
 
 tional area of the heat stack, from formula 19, then becomes, 
 if the velocities are 4, 5.5 and 7 feet per second, 
 
 S X 55 X 144 f. 0091 Hist floor") 
 
 H. S. = = \ .00665 2nd floor !- (22) 
 
 60 X (4, 5.5 or 7) X 3600 [.005253rd floorj 
 
 The air velocity in the stack is based upon the formula 
 v = \/2gh, where h = (effective height of stack) X (t t') -~ 
 (460 + *'); v is in feet per second; * is the temperature of 
 the stack air and ? is the temperature of the room air. 
 The calculated results from this formula are much higher 
 than those obtained in practice because of the shape of 
 cross sections of the stack, the friction of its .sides and the 
 abrupt turns in it. 
 
 From the basis of the net register (figured at 3.5 feet 
 per second) the two quotations by Carpenter and Bird give 
 heat stack areas as follows: first floor, 80 to 88 per 
 cent.; second floor, 55 to 70 per cent.; and third floor, 44 to 
 60 per cent. Good sized stacks are always advisable (see 
 Art. 55), but because of the limited space between the stud- 
 ding it becomes necessary at times to put in a stack that 
 is too small or to increase the thickness of the wall, a thing 
 which the architect is occasionally unwilling to do. From 
 the above figures, checked by existing plants that are 
 working satisfactorily, the following approximate figures, 
 reduced to the basis of the net heat register area, will no 
 doubt give good results. 
 
 {.8 times the net heat register. 1st floor"! 
 .66 times the net heat register. 2nd floorj (23) 
 .5 times the net heat register. 3rd floorj 
 
 43. Vent Stacks: V. S. = . 8 H. S. (24) 
 
 44. Leader Pipes: Since all the air that passes through 
 the stacks must pass through the leader pipes, it seems 
 reasonable to assume that the areas of the two would be 
 equal. It must be remembered, however, that the stacks, 
 because of their vertical position, offer less resistance in 
 friction, while on the other hand the leader pipes, being 
 nearly horizontal and having more crooks and turns in 
 them, will have considerable friction and will consequently 
 retard the air to a greater degree. There will also be some 
 loss of temperature in the air as it passes through the 
 leader pipes, consequently the volume of air entering the 
 leader from the furnace will be greater than that going 
 up the stack. 
 
FURNACE HEATING 53 
 
 It would be well, from the above reasons, to make the 
 area of the leader pipes 
 
 L. P. = (1.1 to 1.2) times the stack area, (25) 
 
 the exact figures to depend upon the length and inclination 
 of the leader and the selection of the diameter of the pipe. 
 
 45. Fresh Air Duct: The area of the fresh air duct is 
 determined largely by experience as in the case of the vent 
 register. It is generally taken 
 
 F. A. D. = .8 times the total area of the leaders. (26) 
 
 Assume the average velocity of the air in the leaders to be 
 6 feet per second and the area of the fresh air duct to be 
 as shown above, then, if the air in each were of the same 
 temperature, the velocity in the fresh air duct would be 
 
 6 -~ . 8 = 7.5 feet per second; but since the temperatures 
 are different the velocities will be in proportion to the ab- 
 solute temperatures. Hence it is, at degrees, .78 X 7.5 
 5.8; at 25 degrees, .82 X 7.5 = 6.2; and at 50 degrees, .88 
 X 7.5 = 6.6 feet per second. It is seen by this, that al- 
 though the area of the fresh air duct is contracted to 80 
 per cent, of that of the leaders, the velocity is in all 
 cases below that of the leaders. It is always well to have 
 a fresh air duct that is large in cross sectional area and 
 free from obstructions and sharp turns. 
 
 46. Grate Area: The grate area of a furnace is esti- 
 mated from the total heat lost from the building, figured 
 on a basis of a certain degree of ventilation. In obtaining 
 the grate area it is necessary to assume the quality of the 
 coal, the efficiency of the furnace and the pounds of coal 
 burned per hour per square foot of grate. The quality of 
 coal selected would be between 12000 and 14000 B. t. u. per 
 pound as shown in Table 11, Appendix. The efficiency of 
 the average furnace is about 60 per cent.; and the coal 
 burned per square foot of grate per hour ranges from 3 to 
 
 7 pounds. Concerning the last point there may be a wide 
 difference of opinion. Higher temperatures in the combus- 
 tion chamber are conducive to economy; hence, to reduce 
 the size of the fire pot and fire small amount of coal with 
 greater frequency would seem to be ,the ideal way. On 
 the other hand, with high temperatures in the combustion 
 chamber, the loss up the chimney is increased. Probably 
 
54 HEATING AND VENTILATION 
 
 the one factor which Is most effective in settling this point 
 is the inconvenience of frequent firing. Furnaces are 
 charged from two to four times each twenty-four hours. 
 This requires a good sized fire pot and a possibility of 
 banking the fires. To allow 5 pounds per hour is probably 
 as good an average as can be made for most coals in fur- 
 nace work. 
 
 Let H' = total heat loss from the building including: 
 ventilation loss; E = efficiency of the furnace; f = value of 
 coal in B. t. u. per pound; and p = pounds of ctfal burned 
 per square foot of grate per hour; then the formula for the 
 square inches of grate area is 
 
 H' X 144 
 
 O. A. = (27) 
 
 E X / X p 
 
 APPLICATION. In the typical illustration, the total heat loss 
 on a zero day by formula is, say, 100000 B. t. u. per hour. 
 This will require 90909 cubic feet of air as a heat carrier. 
 Assuming as a maximum that 10 people will be in the 
 house and that they will need 18000 cubic feet of fresh air 
 per hour for ventilation, this air will carry away approx- 
 imately 22900 B. t. u. per hour, making a total heat loss 
 from the building of 122900 B. t. u. per hour. Now, if the 
 furnace is 60 per cent, efficient and burns 5 pounds of 
 14000 B. t. u. coal per hour per square foot of grate, we 
 will have 
 
 122900 X 144 
 
 0. A. = = 421 square inches 23.2 inches 
 
 .60 X 14000 X 5 
 
 diameter. With coal at 13000 B. t. u. per pound, the grate 
 would be 454 square inches or 24 inches diameter. In either 
 case a 24 inch grate would be selected. With the assump- 
 tions as made above, the formula becomes G. A. = .0035 H' 
 for the better grade of coal, and G. A. = .0037 H f for the 
 poorer grade, from which the following approximate form- 
 ula may be taken: 
 
 O. A. square inches = .0036 H' (28) 
 
 47. Heating Surface: The amount of heating surface *- 
 to be required in any furnace is rather an indefinite quantity. - 1 
 Manufacturers differ upon this point. Some standard may 
 soon be looked for but at present only rough approximations 
 can be stated. One of the chief difficulties is in determin- 
 ing what is, or what is not, heating surface. Some quota- 
 
FURNACE HEATING 55 
 
 tions no doubt include some surface in the furnace that is 
 very inefficient. In estimating 1 , only prime heating surface 
 should be considered, i. e., such plates or materials having 
 direct contact with the heated flue gases on one side and 
 the warm air current on the other. If these plates trans- 
 mit K, B. t. u. per square foot per degree difference of tem- 
 perature, tz, per hour; if, also, one square foot of grate 
 gives to the building E X / X p B. t. u. per hour, there will 
 be the following ratio between the heating surface and 
 grate surface: 
 
 B. 8. E f p 
 
 = (29) 
 
 G. S. Kt, 
 
 APPLICATION. Let the value K tz be 2500, as suggested by 
 W. G. Snow, Trans. A. S. H. & V. E., 1906, page 133, and 
 with the same notations as in Art. 46 obtain 
 H. 8. .6 X 14000 X 5 
 
 G. 8. 2500 
 
 = 17 
 
 In practice this ratio varies anywhere between 12 and 30. 
 
 48. Application of the Above Formula** to a Ten Room 
 Residence: In every design the calculations should be made 
 very complete and the results tabulated for easy reference 
 and as a means of comparison. Such a tabulation is shown 
 in Table IX, giving all the calculated quantities necessary in 
 the installation of the furnace system illustrated in Figs. 
 13, 14 and 15. The value of so condensing the work will be 
 readily apparent. The tabulation of the values used 
 for the various terms of the formula facilitates checking 
 and the detection of errors. Plans should be carefully 
 drawn to scale and accompanied by a sectional elevation. 
 The scale should be as large as can conveniently be made. 
 The location of the building with reference to the points 
 of the compass should always be given, as well as the 
 heights of ceilings and the principal dimensions of each 
 room. There will be a wide variety of practice in making 
 allowance for exposure, floors, ceilings, closets and small 
 rooms not considered of sufficient importance to have inde- 
 pendent heat. The personal element enters into this part of 
 the work very largely. Such points as these are left to 
 the discretion of the designer who, after having had con- 
 siderable experience is able to judge each case very closely. 
 
56 
 
 HEATING AND VENTILATION 
 
 TABLE IX. 
 Formula. H = ? + .25 W + .02 ntf) 70 
 
 
 H O 
 
 4 
 
 55 
 
 Dining 
 Boom 
 
 1 
 OQ 
 
 Kitchen 
 
 a 
 
 JH 
 
 jq 
 
 D 
 
 Chamber 
 
 2 
 
 Chamber i 
 
 h 
 O 
 
 I 
 
 03 
 
 1 
 
 O 
 
 38 
 85 
 78 
 2 
 14000 
 12727 
 140 
 14x16 
 
 28 
 28 
 84 
 2 
 10800 
 9818 
 108 
 12x14 
 
 42 
 52 
 78 
 2 
 18250 
 12045 
 182 
 14x16 
 
 28 
 65 
 56 
 2 
 11900 
 10818 
 119 
 12x14 
 
 29 
 78 
 
 104 
 3 
 
 14000 
 
 42 
 45 
 85 
 1 
 9400 
 8544 
 94 
 12x12 
 61 
 67 
 75 
 10x12 
 45 
 
 88 
 60 
 86 
 1 
 9850 
 9854 
 98 
 12x12 
 64 
 70 
 78 
 10x12 
 48 
 
 26 
 81 ' 
 1 
 6600 
 6000 
 66 
 9x12 
 43 
 47 
 53 
 8x10 
 32 
 
 30 
 22 
 1 
 
 5600 
 5091 
 56 
 8x10 
 36 
 40 
 45 
 8x10 
 27 
 
 14 
 17 
 26 
 2 
 4400 
 4000 
 44 
 8x10 
 28 
 81 
 85 
 8x8 
 22 
 
 315 
 481 
 
 99800 
 
 .25 W 
 
 
 
 H- 
 
 Q 
 
 12727 
 140 
 14x16 
 
 Area of Net Heat Register 
 Heat Register Size 
 
 711 
 
 Area of Heat Stack 
 
 Area of Leader 
 
 100 
 112 
 12x14 
 67 
 
 77 
 86 
 10x12 
 52 
 
 94 
 106 
 12x14 
 64 
 
 85 
 95 
 12x12 
 60 
 
 100 
 112 
 12x14 
 67 
 
 Area of Net Vent Register 
 Vent Register Size 
 
 Area of Vent Staok 
 
 
 
 Remarks 
 
 Allow for cold floor 
 
 low 10 per cent, for closet 
 and exposure 
 
 1 
 
 H 
 
 o> 
 
 s 
 i 
 
 & 
 
 o 
 o 
 
 low 15 per cent, for pantry 
 stair and exposure 
 
 low for floor and hall way 
 on second floor 
 
 low 10 per ct. for exposure 
 
 9 
 
 1 
 
 "o 
 
 tn 
 
 S-i 
 
 i 
 
 i 
 
 10 
 
 ;-, 
 
 O 
 
 Is 
 M 
 
 o o> 
 
 Add closet to room 
 
 Allow 10 per cent.for closet 
 and exposure 
 
 
 
 3 
 
 5J 
 
 3 
 
 * 
 
 * 
 
 Diameter of grate allowing ventilation for ten people = 
 24 inches. Cold air duct = 569 square inches = 18 X 32 inches. 
 
 In selecting the various stacks and leaders it would be 
 well to standardize as much as possible and avoid the extra 
 expense of installing so many sizes. This can be done if 
 the net area is not sacrificed. 
 
BURNACE HEATING 
 
 57 
 
 Fig. 33. 
 
58 
 
 HEATING AND VENTILATION 
 
FURNACE HEATING 
 
 59 
 
 5ctonD FIPOR. PLAN 
 
 Fig. 15. 
 
CHAPTER V. 
 
 FURNACE HEATING AND VENTILATING. 
 
 SUGGESTIONS ON THE SELECTION AND INSTALLATION OF FURNACE 
 HEATING PARTS. 
 
 49. Selection of the Furnace: In selecting a furnace 
 for residence use or other heating service, special attention 
 should be paid to the following- points: easy movement of 
 the air, arrangement and amount of heating surface, shape 
 and size of the fire pot, method of feeding fuel to the fire 
 and type and size of the grate. The furnace gases and the 
 air to be heated should not be allowed to pass through the 
 furnace in too large a unit volume or at too high a velocity. 
 The gases should be broken up in relatively small volumes, 
 thus giving an opportunity for a large heating surface. 
 Concerning the gas passages themselves, it may be said 
 that a number of small, thin passages will be found more 
 efficient than one large passage of equal total area. This 
 is plainly shown in a similar case by comparing the effi- 
 ciency of the water-tube or tubular boiler with that of 
 the old fashioned flue boiler; i. e., a large heating surface 
 is of prime importance. Again, it is desirable that the 
 total flue area within the furnace should be great enough 
 to allow the passage of large volumes of air at low velocities, 
 rather than small volumes at high velocities. This permits 
 of less forcing of the fire and consequently lowers the tem- 
 perature of the heating surface. The latter point will be 
 found valuable when it is remembered that metal at high 
 temperatures transmits through its body a greater amount 
 of impure gases from the coal than when at low tempera- 
 tures. Concerning velocities, it may be said that on account 
 of the low rate of transmission of heat to or from the 
 gases, long flue passages are necessary, so that gases mov- 
 ing at a normal rate will have time to give off or to take 
 up a maximum amount of heat before leaving the furnace. 
 
 Air is heated chiefly by actual contact with heated sur- 
 faces and not much by radiation. Consequently, the ef- 
 ficiency of a furnace is increased when it is designed so 
 that the gases a>nd air in .their movement impinge perpen- 
 dicularly upon the heated surfaces at certain places. This 
 
FURNACE HEATING 
 
 61 
 
 point should not be so exaggerated that there would be 
 serious interference with the draft. The efficiency is also 
 increased if the general movement of the two currents be 
 in opposite directions. 
 
 Furnaces for residences are usually of the portable type, 
 Fig. 16, the same being enclosed in an outer shell composed 
 of two metal casings having a dead air space or an asbes- 
 tos insulation between them. Some of the larger sized 
 
 Fig. 16. 
 
 plants, however, have the furnace enclosed in a permanent 
 casement of brick work, as in Fig. 17. Each of the two 
 types of furnaces give good results. The points usually 
 governing the selection between portable and permanent 
 settings are price and available floor space. 
 
 The cylindrical fire pot is probably better than a con- 
 ical or spherical one, there being less danger of the fire 
 clogging and becoming dirty. A lined fire pot is better 
 than an unlined one, because a hotter fire can be maintained 
 in it with less detriment to the furnace. There is of course 
 a loss of heating surface in the lined pot, and in some forms 
 of furnaces the fire pot is unlined to obtain this increased 
 
62 
 
 HEATING AND VENTILATION 
 
 heating surface. It seems reasonable to assume, however, 
 that the lined pot is longer lived and contaminates the air 
 supply less. 
 
 Pig. 17. 
 
 Fig. 18. 
 
FURNACE HEATING 
 
 63 
 
 Some form of shaking or dumping grate should be se- 
 lected, as a stationary grate is far from satisfactory. Care 
 should be exercised also in the selection of the movable 
 grate, as some forms not only stir up the fire but permit 
 much of it to fall through to waste when being operated. 
 
 The fuel is fed to the fire pot from the door above the 
 fire. This is called a top-feed furnace. In some forms, how- 
 ever, the fuel is fed up through the grate. This is called 
 the under-feed furnace, Fig. 18, and is rapidly gaining in 
 favor. The latter type requires a rotary ring grate with 
 the fuel entering up through its center. 
 
 The size of the furnace may be obtained from the estimated 
 heating capacity in cubic feet of room space as given in the 
 sample Table 16, Appendix. Another and perhaps a bet- 
 ter way, and one that serves as a good check on the above, 
 is to select a furnace from the calculated grate area. See Art. 
 46. Having selected the furnace by the grate area, check 
 this with the table for the estimated heating capacity 
 and the heating surface to see if they agree. 
 
 What is known as a combination heater is shown in 
 Fig. 19. It is used for heating part of the rooms of a resi- 
 dence by warm air, as in 
 regular furnace work, and 
 the remainder of the rooms 
 by hot water. In this 
 manner, rooms to be ven- 
 tilated as well as heated 
 may be connected by the 
 proper stacks and leaders 
 to the warm air deliveries 
 of such a combination 
 heater, while rooms requir- 
 ing less ventilation or heat 
 only may have radiators 
 installed and connected to 
 the flow and return pipes 
 shown In the figure. Also, 
 because of the difficulty 
 in heating certain exposed 
 rooms, with warm/ air, these 
 rooms may be supplied by 
 the positive heat of the 
 
 Fig. 19. 
 more reliable water circulation. 
 
64 HEATING AND VENTILATION 
 
 50. Location of the Furnace: Where other things do 
 not interfere, a furnace should be set as near the center 
 of the house plan as possible. Where this is not wise or 
 possible, preference should be given to the colder sides, say 
 the north or west. In any case, it is advisable to have the 
 leader pipes as near the same length as can be made. The 
 lengtn of the smoke pipe should be as short as possible, 
 but it will be better to have a moderately long smoke pipe 
 and obtain a more uniform length of leader pipes than to 
 have a short smoke pipe and leaders of widely different 
 lengths. 
 
 The furnace should be set low enough to get a good 
 upward slope to the leaders from the furnace to their re- 
 spective stacks. This should be not less than one inch per foot 
 of length and more if possible. These leader pipes should be 
 dampered near the furnace. 
 
 The location of the furnace will call forth the best 
 judgement of the designer, since the right or wrong decis- 
 ion here can make or mar the whole system more com- 
 pletely than in any other manner. 
 
 51. Foundation: All furnaces should have directions 
 from the manufacturer to govern the setting. Each type of 
 furnace requires a special setting and the maker should 
 be-t be able to supply this desired Information concerning 
 it. Such information may be safely followed. In any case 
 the furnace should be mounted on a level brick or concrete 
 foundation specially prepared and well finished with cement 
 mortar on the inside, since this interior is in contact with 
 the fresh air supply. 
 
 52. Fresh Air Duct: This is best constructed of hard 
 burned brick, vitrified tile or concrete, laid in four inch 
 walls with cement mortar and plastered inside with ce- 
 ment plaster, all to be air tight. The top should be covered 
 with flag stones with tight joints. The riser from this, 
 leading to the outside of the building, may be of wood, tile 
 or galvanized iron, and the fresh air entrance should be 
 vertically screened. The whole should be with tight joints 
 and be so constructed as to be free from surface drainage, 
 dirt, rats and other vermin. This duct may be made of 
 metal or boards as substitutes for the brick, tile or concrete. 
 Board construction is not so satisfactory, although it is the 
 
FURNACE HEATING 
 
 cheapest, and whenever used should be carefully constructed, 
 An opening- may be made in the fresh air duct near the 
 furnace for the purpose of admitting the duct which carries 
 the recirculated air from the rooms to the furnace. Both 
 of these ducts should have dampers that may be opened or 
 closed. See Fig. 12. Both ducts should also be provided 
 with doors that can be opened temporarily to the cellar 
 air. Sometimes it is desirable to have two or more fresh 
 air ducts leading- from the different sides of the house to the 
 furnace so as to get the benefit of 
 any change in air pressure on the 
 outside of the building. 
 
 Proper arrangements may be 
 made for pans of clear water in the 
 air duct near the furnace to give 
 moisture to the air current, although 
 only a small amount of moisture 
 will be taken up at this point. In 
 most cases where moistening pans 
 are used, they are installed in con- 
 nection with the furnace itself. A 
 good way to moisten the air fs to 
 have moistening pans built in just 
 behind the register face, Fig. 20. 
 These pans are shallow and should 
 not be permitted to seriously inter- 
 fere with the amount of air enter- 
 ing- through the register. 
 
 Fig. 20. 
 
 53. Recirculatlng Duct: A duct should be provided 
 from some point within the building, through the cellar 
 and entering into the bottom of the furnace or into the 
 fresh air duct near the furnace; this is to carry the warm 
 air from the room back to the furnace to be reheated for 
 use again within the building. In many cases tin or gal- 
 vanized iron is used for the material for the recirculating 
 pipe. Where this enters the furnace, or the fresh air duct 
 near the furnace, it should be planned with sufficient turn 
 so that the air would be projected through the furnace, thus 
 placing a hindrance to the fresh cold air from following 
 back through this pipe to the rooms. The exact location 
 of the same will depend, of course, on the location of the 
 register installed for this purpose. The construction of the 
 
66 
 
 HEATING AND VENTILATION 
 
 duct may agree with the similar construction of the fresh 
 air duct. 
 
 54. Leader Pipes: All leader pipes should be round 
 and free from unnecessary turns. They should be made 
 from heavy galvanized iron or tin and should be laid to an 
 upward pitch of not less than one inch per foot of length, 
 and more if it can possibly be given. The connections with 
 the furnace should be straight, but if a turn is necessary, 
 provide long radius elbows. All connections to risers or 
 stacks should be made through long radius elbows. Rect- 
 angular shaped loots having attached collars are sometimes 
 used, but these are not so satisfactory because of the im- 
 
 Fig. 21. 
 
FURNACE HEATING 
 
 pirigemcnt of the air against the flat side of the stack; also 
 because of the danger of the leader entering too far into 
 the stack and thus shutting off the draft. Leaders should 
 connect to the first floor registers by long radius el- 
 bows. Leader pipes should have as few joints as possible 
 and these should be made firm and air tight. Fig. 21 shows 
 different methods of connecting between leaders and stacks, 
 also between leaders and registers. 
 
 The outside of all leader pipes should be covered to 
 avoid heat loss and to provide additional safety to the plant. 
 The covering is usually one or more thicknesses of asbes- 
 tos paper or mineral wool. 
 
 55. Stacks or Risers: The vertical air pipes leading to 
 the registers are called stacks or risers. They are rect- 
 angular or oblong in section and are usu- 
 ally fitted within the wall. See Big. 22. 
 The size of the studding and the distances 
 they are set, center to center, limit the 
 effective area of the stack. All stacks 
 should be insulated to protect the wood- 
 work. This is done by making the stack 
 small enough to clear the woodwork by 
 at least one-quarter inch and then wrapping 
 it with some non-conducting material 
 such as asbestos paper held in place by 
 wire. 
 
 Another way, and one which is prob- 
 ably more satisfactory, is to have pat- 
 ented double walled stacks having an air 
 space between the walls all around. The 
 outside wall is usually provided with vent 
 holes which allow the circulation of air 
 between the walls, thus protecting any 
 one part from becoming overheated. All 
 stacks should be made with tight joints 
 and should have ears or flaps for fasten- 
 ing to the studding. Patented stacks are 
 
 made in standard sizes and of various lengths. The sizes 
 ordinarily found in practice are about as given in Table 
 17, Appendix. 
 
 A stack is sometimes run up in a corner or in some 
 recess in the wall of a room where its appearance, after 
 
 Fig. 22. 
 
68 HEATING AND VENTILATION 
 
 being finished in color to compare with that of the room, 
 would not be unsightly. This is necessary in any case 
 where the stack is installed after the building is finished. 
 This method is desired by some because of its additional 
 safety and because more stack area may be obtained than 
 is possible when placed within a thin wall. 
 
 All stacks should be located in partition walls looking 
 toward the outside or cold side of the room. This protects 
 the air current from excessive loss of heat, as would be the 
 case in the outside walls. It also provides a more uniform 
 distribution of air. 
 
 The area of the stack best adapted to any given room 
 is another point in furnace work which brings out a wide 
 diversity of practice. Results from different installations 
 show variations as great as 50 per cent. This is not so 
 noticeable in the first floor rooms as it is in those of the 
 second floor. In a great many cases the architect specifies 
 light partition walls between large upper rooms, say, four 
 inch studding set sixteen inch centers, between twelve foot 
 by fifteen foot rooms, heavily exposed. From theoretical 
 calculation of heat losses, these rooms require larger stacks 
 than can be placed between studding as stated; however, it 
 is very common to find such rooms provided for in this way. 
 One possible excuse for it may be the fact that the room is 
 designed for a chamber and not for a living room. Any 
 sacrifice in heating capacity in any room, even though it be 
 used as a sleeping room only, should be done at the sug- 
 gestion of the purchaser and not at the suggestion of the 
 architect or engineer. Every room should be provided with 
 facilities for heat as though it were to be used as a living 
 room in the coldest weather, then there would be fewer 
 complaints of defective heating plants and less migrating 
 from one side of the house to the other on cold days. 
 
 This lack of heating capacity for any room is some- 
 times overcome by providing two stacks and registers in- 
 stead of one. This plan is very satisfactory because one 
 of the registers may be shut off in moderate weather. How- 
 ever, it requires an additional expense which is scarcely 
 justified. A possible improvement would be for the archi- 
 tect to anticipate such condition and provide suitable 
 partition walls so that ample stack area could be put in. 
 The ideal conditions will be reached when the architect act- 
 
FURNACE HEATING 
 
 ually provides air shafts of sufficient size to accommodate 
 either a round or a nearly square stack. When this time 
 comes a great many of the furnace heating 1 difficulties will 
 have been solved. 
 
 A double stack supplying air to two rooms is some- 
 times used, having a partition separating the air currents 
 near the upper end. This practice is questionable because 
 of the liability of the pressure of air in the room on the 
 cold side of the house forcing the heated air to the other 
 room. A better method is to have a stack for each room 
 to be heated. 
 
 56. Vent Stacks: Vent stacks should be placed on the 
 inner or partition walls and should lead to the attic. They 
 may there be gathered together in one duct leading to a 
 vent through the roof if desired. 
 
 57. Air Circulation Within the Room: The location of 
 the heat register, relative to the vent register, will deter- 
 
 Fig. 23. 
 
 mine to a large degree the circulation of the air within the 
 room. Fig. 23, a, b, c and d, shows clearly the effect of the 
 different locations. The best plan, from the standpoint of 
 heating, is to enter the air at a point above the heads of the 
 
70 HEATING AND VENTILATION 
 
 occupants and withdraw it from the floor line, at or near the 
 same side from which the air enters. This gives a more uni- 
 form distribution as shown by the last figure. It is doubtful, 
 however, if this method will give the best ventilation in 
 crowded rooms where the foul air naturally collects at the 
 top of the room. Furnace heating is not so well cared for 
 in this regard as are the other forms of indirect heating, the 
 air being admitted at the floor line and required to find its 
 own way out. 
 
 58. Fan Furnace Heating System: In large furnace 
 installations where the air is carried in long ducts that are 
 nearly, if not quite, horizontal, and where a continuous sup- 
 ply of air is a necessity in all parts of the building, a com- 
 bination fan and furnace system may be installed. These 
 are frequently found in hospitals, schools and churches. Such 
 a system may be properly designated a mechanical warm 
 air system. In comparison with other mechanical systems, 
 however, it is simpler and cheaper. The arrangement may 
 be illustrated by Fig. 66 with the tempering coils omitted 
 and the furnace substituted for the heating coils. The fan 
 should .always be between the air inlet and the furnace so as 
 to keep a slight pressure above atmosphere on the air. side 
 and thus reduce the leakage of the fuel gas through the 
 joints of the furnace. By this arrangement there is less 
 volume of air to be handled by the fan and a smaller sized 
 fan may be used. 
 
 Fan-furnace systems may be set in multiple if desired, i. 
 e., one fan "operating in connection with two or more fur- 
 naces. Paddle wheel fans are preferred, although the disk 
 wheel may be used where the pipes are large and where 
 the air must be carried but short distances. For fan types 
 see Chapter IX. 
 
 59. Suggestions for Operating Furnaces: Furnaces are 
 designated hard coal and soft coal, depending upon the type and 
 the construction of the grate, hence the grade of coal best 
 adapted to the furnace should be used. The size of the open- 
 ings in the grate should determine the size of the coal used. 
 
 Keep the fire pot well filled with coal and have it evenly 
 distributed over the grate. 
 
 Keep the fire clean. Clinkers should be removed from 
 the fire once or twice daily. It is not necessary to stir the 
 fire so completely as to waste the coal through the grate. 
 
FURNACE HEATING 71 
 
 When replenishing a poor fire do not shake the fire, but 
 put some coal on and open the drafts. After the coal is well 
 ignited then clean the fire. 
 
 The ash pit should be frequently cleaned, because an 
 accumulation of ashes below the grate soon warps the grate 
 and burns it out. 
 
 Keep all the dampers set and properly working. 
 
 Have a damper in the smoke pipe and keep it open only 
 so far as is necessary to create a draft. 
 
 Keep the water pans full of water. 
 
 Clean the furnace and smoke pipe thoroughly in all parts 
 at least once each year. 
 
 Keep the fresh air duct free from rubbish and impurities. 
 
 Allow plenty of pure fresh air to enter the furnace at all 
 times. In cold weather part of this supply may be cut off. 
 
 Have the basement well ventilated by means of outside 
 wall ventilators, or by special ducts leading to the attic. 
 Never permit the basement air to be circulated to the living 
 rooms. 
 
 To bank the fires for the night, clean the fire, push the 
 coals near the rear of the grate, cover with fresh fuel to 
 the necessary depth (this will be found by experience), set the 
 drafts so they are nearly closed and partially open the fire 
 doors. 
 
72 HEATING AND VENTILATION 
 
 REFERENCES. 
 References on Furnace Heating:. 
 
 TECHNICAL BOOKS. 
 
 Snow, Prin. of Heat, p. 27. Snow, Furnace Heat., p. 7. I. C S., 
 Prin. of Heat. & Vent., p. 1237. Carpenter, Heat. & Vent. Bldgs., p. 
 310. Hubbard, Power, Heat. & Vent., p. 423. 
 
 TECHNICAL PERIODICALS. 
 
 Engineering Review. Warm Air Furnace Heating, C. L. Hub- 
 bard, Nov. 1909, p. 42; Dec. 1909, p. 45; Jan. 1910, p. 66; Feb. 
 1910, p. 48; March 1910, p. 51; May 1910, p. 48; Aug. 1910, p. 
 29. Warm Air System of Heating and Ventilating, R. H. 
 Bradley, May 1910, p. 32 Mechanical Furnace Heating and 
 Ventilating, June 1910, p. 49. Heating and Vent. System 
 installed in Public School, Fairview, N. J., July 1910, p. 47. 
 Combined System of Warm Air and Hot Water Heat, for a 
 Residence, Jan. 1909, p. 26. Warm Air Heating Installation 
 in a Brooklyn Residence, March 1909, p. 38. The Heating and 
 Ventilating Magazine. Advanced Methods of Warm Air Heat- 
 ing, A. O. Jones, Aug. 1904, p. 88. Air Pipes, Sizes Required 
 for Low Velocities, Oct. 1905, p. 7. Report of Committee 
 (A. S. H. V. E.) to Collect Data on Furnace Heating, Jan. 
 1906, p. 35. An Improved Application of Hot Air Heating, 
 A. O. Jones, July 1906, p. 31. Domestic Engineering. Sanitation 
 in Hot Air Heating, James C. Bayles, Vol. 25, No. 6, Sept. 
 25, 1903, p. 261. Trans. A. 8. H. & V. E. Test of Hot Air Grav- 
 ity System, R. C. Carpenter, Vol. IX, p. 131. Heat Radiators 
 using Air instead of Water and Steam, Geo. Alysworth, Vol. 
 IX, p. 259. Velocities in Pipes and Registers in a Warm Air 
 System, Vol. XII, p. 352. Relative Size Hot Air Pipes, Vol. 
 XIII, p. 270. Velocity of Air in Ducts, Vol. VII, p. 162. 
 
CHAPTER VI. 
 
 HOT WATER AND STEAM HEATING. 
 
 DESCRIPTION AND CLASSIFICATION OF THE SYSTEMS. 
 
 60. Hot "Wafer and Steam Systems Compared to Fur- 
 nace Systems: As compared to the warm air or furnace 
 plant, the hot water and the steam installations are more 
 complicated in the number of parts; they use a more cum- 
 bersome heat carrying medium, for which a return path to 
 the boiler must be provided; and have parts, in the form 
 of radiators, which occupy valuable room space. But the 
 steam and hot water plants have the advantage in that 
 their circulations, and hence their transference of heat, 
 are quite positive, and not affected by wind pressures. A 
 hot water or a steam system will carry heat just as readily 
 to the windward side of a house as it will to the leeward 
 side, a point which, with a furnace installation, is known 
 to be quite impossible. F urnace heating, on the other hand, 
 has the advantage of inherent ventilation, while the hot 
 water and steam systems, as usually installed, provide no 
 ventilation except that due to air leakage. 
 
 61. The Parts of Hot Water and Steam Systems: A hot 
 
 water or a steam system may be said to consist of three 
 principal parts: first, the boiler or heat generator; second, 
 the radiators or heat distributors; and third, the connecting 
 pipe-lines, which provide the circuit paths for the hot water 
 or the steam. In the hot water system it is essential that 
 the heat generator be located at the lowest point in the 
 circuit, for, as was explained in Art. 5, the only motive 
 force is that due to the convection of the water. In the 
 steam system this is not essential, as the pressure of the 
 steam forces it outward to the farthest points of the system. 
 The water of condensation may or may not be returned by 
 gravity to the boiler. Hence, with a steam system a radiator 
 may be placed below the boiler, if its condensation be trapped 
 or otherwise taken care of. 
 
74 
 
 HEATING AND VENTILATION 
 
 62. Definitions: In speaking of the piping of heating 
 installations, several terms, commonly used by heating en- 
 gineers, should be thoroughly understood. The large pipes 
 in the basement connected directly to the source of heat, 
 and serving as feeders or distributors of the heating me- 
 dium to the pipes running vertically in the building, are 
 known as mains. The flow mains are those carrying^ steam 
 
 Fig. 24. 
 
 Pig. 21 
 
 or hot water from the source of heat towards the radiators, 
 and the return mains are those carrying water or 
 condensation from the radiators to the source of 
 heat. Those vertical pipes in a building to which 
 the radiators are directly connected are called risers, 
 while the short horizontal pipes from risers to radi- 
 ators are usually termed riser arms. As there are flow 
 mains and return mains, so also, there are flow risers and 
 return risers. A radiator should have at least two tappings, 
 one below for the entry of the heating medium, and one 
 on the end section opposite, near the top for air discharge 
 as shown by the connected steam radiator of Fig. 24. It 
 may have three, a flow tapping and a return tapping at the 
 bottom of the two end sections, and the third or air tapping 
 near the top of the end section at the return end as shown 
 by the connected hot water radiator of Fig. 25. A return 
 
HOT WATER AND STEAM HEATING 
 
 75 
 
 main traversing the basement above the water line of the 
 boiler is designated as a dry return and carries both steam 
 and water of condensation; one in such position below the 
 water line as to be filled with water is designated a wet 
 return, and the returns of all two-pipe radiators connecting 
 with wet returns are said to be sealed. 
 
 63. Classification: One classification of hot water and 
 steam systems is based upon the position and manner in 
 which the radiators are used. The system which is, per- 
 haps, most familiar is the one wherein radiators are placed 
 directly within the space to be heated. This heating is ac- 
 
 Fig. 26. 
 
 Big. 27. 
 
 complished by direct radiation and by air convection cur- 
 rents through the radiators, no provision being made for a 
 change of air in the room. This is known as the direct 
 system, and, while it causes movements of the air in the 
 room, it produces no real ventilation. See Fig. 26. 
 
 In the direct-indirect system, the radiator is also 
 placed within the space or room to be heated, but its lower 
 half is so encased and connected to the outside of the build- 
 
HEATING AND VENTILATION 
 
 ing that fresh air is continually drawn up through the 
 radiator, is heated, and thrown out into the room as sfoown 
 by Fig 1 . 27. Thus is established a ventilating system mor^ 
 or less effective. 
 
 In the purely indirect system, Fig. 28, 'the radiating sur- 
 face is erected somewhere remote from the rooms to be 
 neated, and ducts carry the heated air from the radiator 
 to the rooms either by natural convection, as in some in- 
 stallations, or by fan or blower pressure, as in others. 
 When all the radiation for an entire building is installed 
 
 Fig. 28. 
 
 together in one basement room, and each room of the build- 
 ing has carried to it, its share of heat by forced air through 
 ducts from one large centralized fan or blower, the system 
 is called a Plenum System, and is given special consideration 
 in Chapters IX to XL 
 
 64. A second classification of steam and hot water sys- 
 tems is made according to the method of pipe connection 
 between the heat generator and the radiation. That known 
 as the one-pipe system, Fig. 29, is the simplest in construc- 
 tion and is preferred by many -for the steam installations. 
 As the name indicates, its distinguishing feature is the 
 single pipe leading from the source of heat to the radiator, 
 the steam and the returning condensation both using this 
 path. In the risers and connections, the steam and con- 
 densation flow in opposite directions, thus requiring larger 
 pipes than where a flow and a return are both provided. 
 In this system the condensation usually flows with the 
 steam in the main, and not against it, until it reaches such 
 a point that it may be dripped to a separate return 
 and then led to the boiler. In the so-called one-pipe 
 hot water system, radiators have two tappings and two 
 risers, but the flow riser is tapped out of the top of the 
 
HOT WATER AND STEAM HEATING 
 
 77 
 
 Fig. 29. 
 
 single basement main, while the return riser is tapped into 
 the bottom of that same main by either of the special fit- 
 tings shown in section in Fig. 30. The theory is that the 
 hot water from the boiler travels 
 along the top of the horizontal base- 
 ment main, while the cooler water from 
 the radiators travels along the bottom 
 of this same main. Hence the neces- 
 sity for tapping flow risers out of the 
 top and return risers into the bottom 
 of this main, thus avoiding a mixing 
 of the two streams. Where mains are 
 short and straight as in the smaller 
 Pig-. 30. residence installations, this system 
 
78 HEATING AND VENTILATION 
 
 seems to give satisfaction; but it is very evident that, where 
 basement mains are long and more complicated, a mixing 
 f the two streams is unavoidable, thus rendering the sys- 
 tem unreliable. 
 
 The two-pipe system is used on both steam and hot 
 water installations. For steam work it is probably no 
 better than the one-pipe system but for hot water work it 
 is much preferred. In this system two separate and dis- 
 tinct paths may be traced from any radiator to the source 
 of heat." In the basement are two mains, the flow and the 
 return, and the risers from these are always run in pairs, 
 the flow riser on one side of a tier of radiators, the return 
 riser on the other side. A two-pipe steam system must 
 have a sealed return. Typical two-pipe main and riser con- 
 nections are shown in E ig. 31. 
 
 Fig. 31. 
 
 Fig. 32. 
 
 65. A third system, known as the attic main, or Mills 
 system, has found much favor with heating engineers in 
 the installation of the larger steam plants although it could 
 
HOT WATER AND STEAM HEATING 79 
 
 be applied as well to the larger iiot water plants. The 
 distinguishing- feature, when applied to a steam system, 
 is the double main and single riser, so arranged that the 
 condensation and live steam flow, in the same direction. 
 This is accomplished by taking the live steam directly to 
 the attic by one large main, which there branches, as need 
 be, to supply the various risers, only one riser being used 
 for each tier of radiators and the direction of flow of both 
 steam and condensation in risers being downward. Hence, 
 this system avoids the unsightliness of duplicate risers, as 
 in the two-pipe system, and avoids the disadvantage of the 
 one-pipe basement system, the last named having steam 
 and condensation flowing in opposite directions in the same 
 pipe. Fig. 32 shows two common methods of connecting 
 risers and radiators with this system. 
 
 66. Vacuum Systems for Steam: Most commonly, the 
 systems mentioned, when steam, are installed as the so- 
 called low pressure systems, which term indicates an abso- 
 lute pressure of about 18 pounds per square inch or 3Y 2 
 pounds gage pressure. On extensive work, it has been 
 found advantageous to install a vacuum system to increase 
 economy, also to insure positive steam circulation by prompt 
 removal of condensation through vacuum returns. Even 
 for comparatively small residence installations vacuum ap- 
 plications of various kinds are becoming common. 
 
 Vacuum systems may be divided into two classes, ac- 
 cording to the way in which the vacuum is maintained. For 
 comparatively small plants, not using exhaust steam, the 
 vacuum is maintained by mercury seal connections, and 
 these plants are usually referred to as mercury seal vacuum 
 systems. These mercury seals may be attached to any 
 standard one or two-pipe system by merely replacing the 
 ordinary air valve by a special connection, which in real- 
 
81) 
 
 HEATING AND VENTILATION 
 
 ity is only a barometer. An iron tube, Fig. 33, dips just 
 below the surface of the mercury in the well on the floor, 
 and extends vertically to the radiator air tap- 
 ping to which the tube connects by a fitting 
 which will allow air to pass into and through 
 the barometer, but will not allow steam to 
 pass. When the system is first fired up and 
 steam is raised to several pounds gage, the air 
 leaves all the radiators by bubbling through 
 the mercury seal at the end of the vertical 
 iron tube. If the fire is then allowed to go out, 
 the steam will condense, and produce an almost 
 perfect vacuum in the entire system, provided 
 all pipe fitting has been carefully done. This 
 system may be operated as a vacuum system 
 at 4 or 5 pounds absolute pressure and have 
 the water boiling as low as 150 to 160 degrees. 
 The flexibility of this system recommends it 
 highly. Applied to a residence or store, the 
 plant may be operated during the day at sev- 
 eral pounds gage pressure, if necessary, but 
 when fires are banked for the night, steam re- 
 mains in all pipes and radiators as long as the 
 temperature of the water does not fall much 
 below 150 degrees. This is in sharp contrast 
 with the ordinary system, where steam disap- 
 pears from all radiators as soon as the water 
 temperature drops below 212 degrees. The 
 promptness with which heat may be obtained in the morn- 
 ing is noteworthy, for, if the vacuum has been maintained, 
 steam will begin to circulate as soon as the water has been 
 raised to about 150 degrees. According to demands of the 
 weather, the radiators may be kept at any temperature 
 along the range of 150 to 220 degrees, thus giving great 
 flexibility. 
 
 Instead of having a barometric tube at each radiator, 
 one mercury seal may be supplied in the basement, and the 
 air tappings of all radiators connected to the top of the 
 tube by ^4 inch piping. The Trane vacuum system is usually 
 so installed, and is an excellent example of this vacuum 
 type. 
 
 I 
 
HOT WATER AND STEAM HEATING 
 
 81 
 
 67. The second class of vacuum systems includes those 
 designed especially for use in office buildings, and where- 
 in the vacuum is maintained by an aspirator, exhauster or 
 pump of some description. This exhauster may handle only 
 the air of the system, that is, it may be connected only 
 to the air tappings of all radiators, as in the Paul system, 
 Fig. 34, or the exhauster may handle both air and con- 
 densation and be connected to the return tappings of all 
 radiators, as in the Webster system, Fig. 35. The Paul 
 
 Fig. 34. 
 
 Fig. 35. 
 
 system is fundamentally a one-pipe system, using exhaust 
 cr live steam and maintaining its circulation without back 
 pressure, by exhausting each radiator at its air tapping, 
 and also exhausting the condensation from the basement 
 tank in which it has been collected by gravity. For an 
 aspirator this system uses either air, steam, or hot water, 
 as the conditions may determine. The Webster system is 
 fundamentally a two-pipe system and exhausts from the 
 radiators both the air and water of condensation, all radi- 
 ator returns being- connected to the (usually) steam driven 
 vacuum pump. These systems are designed to use both exhaust 
 and live steam, and hence are finding wide application in the 
 modern heating of manufacturing plants. See also Chapter 
 XII. 
 
CHAPTER VII. 
 
 HOT WATER AND STEAM HEATING. 
 
 RADIATORS, BOILERS, FITTINGS AND APPLIANCES- 
 
 The various systems just described are merely different 
 ways of connecting the source of heat to the distributors 
 of heat, i. e., methods of pipe connections between heater 
 and radiators. Many forms of radiators exist, as well as 
 many types of heaters and boilers, each adapted to its own 
 peculiar condition. It is in this choice of the best adapted 
 material where the heating engineer shows the degree of 
 his practical training, and the closeness with which he fol- 
 lows the latest inventions, improvements and applications. 
 
 68. Classification as to Material: Radiators may be 
 classified, according to material, as cast iron radiators, 
 pressed steel radiators and pipe coil radiators. Cast radi- 
 ators have the hollow sections cast, as one piece, of iron. 
 The wall is usually about % inch to % inch thick, and is 
 finally tested to a pressure of 100 pounds per square inch. 
 Sections are joined by wrought iron nipples which, at the 
 same time, serve to make passageways between any one 
 section and its neighbors for the current of heating me- 
 dium, whether of steam or hot water. Cast iron radiators 
 have the disadvantage of heavy weight, danger of break- 
 ing by freezing, occupying much space, and having a com- 
 paratively large internal volume, averaging a pint and a 
 half per square foot of surface. 
 
 Pressed radiators are made of sheet steel of No. 16 
 gage, and, after assembly, are galvanized both inside and 
 out. Each section is composed of two pressed sheets that 
 are joined together by a double seam as shown at a, Fig. 
 36, which illustrates a section through a two-column unit. 
 
 Fig. 36. 
 
 The joints between the sections or units are of the same 
 kind. It is readily seen that such construction tends to- 
 ward a very compact radiating surface. Pressed radia- 
 
HOT WATER AND STEAM HEATING 83 
 
 tors are comparatively new, but, in their development, 
 promise much in the way of a light, compact radiation. In 
 comparison with the cast iron radiators, they are free from 
 the sand and dirt on the inside, thus causing less trouble 
 with valves and traps. The internal volume will approxi- 
 mate one pint per square foot of surface. See Fig. 37. 
 
 Radiators composed of pipes, in various forms, are 
 commonly referred to as coil radiators. They are daily 
 becoming less common for direct and direct-indirect work, 
 because of their extreme unsightliness. Piping is still 
 much used as the heat radiator in indirect and plenum 
 systems, although both cast and pressed radiators are now 
 designed for both of these purposes where low pressure 
 steam is used. In all coil radiator work, no matter for 
 what purpose, 1 inch pipe is the standard size. However, 
 in some cases pipes are used as large as 2 inches in diam- 
 eter. This 1 inch pipe is rated at 1 square foot of heating 
 surface per 3 lineal feet and has about 1 pint of containing 
 capacity per square foot of surface. 
 
 69. Classification as to Form: Radiators may again be 
 classified in accordance with form, into' the one, two, three, 
 and four-column floor types, the wall type, and the flue 
 type. See Fig. 37. These terms refer only to cast and 
 pressed radiators. By the column of a radiator is meant 
 one of the unit fluid-containing elements of which a sec- 
 tion is composed. When the section has only one part or 
 vertical division, it is called a single-column or one-column 
 type; when there are two such divisions, a two-column; 
 when three, a three-column; and when four, a four- 
 column type. What is known as the wall type radiator is 
 a cast section one-column type so designed as to be of 
 the least practicable thickness. It presents the appear- 
 ance, often, of a heavy grating, and is so made as to 
 have from 5 to 9 square feet of surface, according to the 
 size of the section. One-column floor radiators made with- 
 out feet are often used as wall radiators. A flue radiator 
 is a very broad type of the one-column radiator, the parts 
 being so designed that the air entering between the sections 
 at the base is compelled to travel to the top of the sections 
 before leaving the radiator. This type is therefore well 
 adapted to direct-indirect work. See Fig. 37. 
 
HEATING AND VENTILATION 
 
 Stairway Type Dining Room Type Flue Type Circular Type 
 
 CAST RADIATORS 
 
 Wall Type 
 
 Two-Column 
 Type 
 
 Three-Column 
 Type 
 
 Four-Column 
 Type 
 
 PRESSED RADIATORS 
 
 Single-Column Two-Column 
 Type Type 
 
 Three-Column 
 Type 
 
 Fig:. 37. 
 
 Wall Type 
 
HOT WATER AND STEAM HEATING 85 
 
 Many special shapes of assembled radiators will be 
 met with, but they will always be of some one of the fun- 
 damental types mentioned above. For instance, there are 
 "stairway radiators," built up of 'successive heights of 
 sections, so as to fit along the triangular shaped wall under 
 stairways; there are "pantry" radiators built up of sections 
 so as to form a tier of heated shelves; there are "dining 
 room" radiators with an oven-like arrangement built into 
 their center; and there are "window radiators" built with 
 low sections in the middle and higher ones at either end, 
 so as to fit neatly around a low window. Fig. 37 shows a 
 number of these common forms as used in practice. 
 
 70. Classification as to Heating Medium: A third class- 
 ification of radiators, according to heating medium em- 
 ployed, gives rise to the terms steam radiator and hot 
 water radiator. Casually, one would notice little difference 
 between the two, but in construction there is a vital differ- 
 ence. Steam radiation has the sections joined by nipples 
 along the bottom only, but hot water radiation, has them 
 joined along the top as well. This is quite essential to the 
 proper circulation of the water. Steam radiation is always 
 tapped for pipe connections at the bottom. Hot water rad- 
 iation may have the flow connection enter at the top, and 
 the return connection leave at the bottom, or may have 
 both connections at the bottom. Hot water radiation can 
 be heated very successfully with steam, but steam radia- 
 tion cannot be used with hot water. 
 
 71. High versus JLow Radiators: In the adoption of a 
 radiator height, the governing feature is usually the space 
 allowed for the radiator. Thus, if a radiator of 26 inches 
 in height requires so many sections as to become too long, 
 then a 32 inch or a 38 inch section may be taken. In gen- 
 eral, however, low radiators should be used as far as 
 possible, for, with a high radiator, the air passing up along 
 the sides of the sections becomes heated before reaching the 
 top, and therefore, receives less heat from the upper half 
 of the radiator, since the temperature difference here is 
 small. Hence, the statement that low radiators are more 
 efficient, that is, will transmit more B. t. u. per square 
 foot per hour than will the high radiators. 
 
86 
 
 HEATING AND VENTILATION 
 
 72. Effect of Condition of Radiator Surface on the 
 Transmission of Heat: The efficiency of a radiator depends 
 very largely upon the condition of its outer surface, a 
 rough surface giving off very much more heat than a 
 smooth surface. Painting, bronzing, shellacing or cover- 
 ing the radiator in any manner affects the ability of the 
 radiator to impart heat to the air circulating around it. 
 Various tests bearing upon this question have been con- 
 ducted, agreeing fairly well in general results. A series 
 of tests conducted by Prof. Allen at the University of 
 Michigan, indicated that the ordinary bronzes of copper, 
 zinc or aluminum caused a reduction in the efficiency below 
 that of the ordinary rough surface of the radiator of 
 about 25 per cent., while white zinc paint and white enamel 
 gave the greatest efficiency, being slightly above that of 
 the original surface. Numerous coats of paint, even as high 
 as twelve, seemed to affect the efficiency in no appreciable 
 manner, it being the last or outer coat that always de- 
 termined at what rate the radiator would transmit its heat. 
 
 TABLE X. 
 Dimensions and Surfaces of Radiators, per Section. 
 
 
 si 
 
 g 
 
 "g 
 
 Radiator Heights. 
 
 Type of 
 Radiator 
 
 IS 
 
 1 = 
 
 
 
 
 I 
 
 
 
 
 
 
 
 
 
 
 
 *1 
 
 as 'H 
 
 45" 
 
 44" 
 
 38" 
 
 82" 
 
 26" 
 
 23" 
 
 22" 
 
 20" 
 
 18" 
 
 16" 
 
 14" 
 
 
 
 53 
 
 
 
 
 
 
 
 
 
 
 
 
 lOol. O. I 
 
 5 
 
 3 
 
 
 
 3 
 
 2% 
 
 2 
 
 1% 
 
 
 
 1% 
 
 
 
 
 2 Ool. O. I 
 
 8 
 
 8 
 
 5 
 
 
 
 4 
 
 8>i 
 
 2% 
 
 2% 
 
 
 2 
 
 
 
 
 8 Ool. O.I 
 
 9% 
 
 3 
 
 .... 
 
 6 
 
 5 
 
 4% 
 
 3K 
 
 
 
 3 
 
 
 
 2% 
 
 
 
 4 Ool O I. 
 
 ,. 
 
 -,/ 
 
 QT/ 
 
 
 8 
 
 gi/ 
 
 5 
 
 
 4 
 
 
 8 
 
 
 
 
 19* 
 
 3 
 
 
 
 7 
 
 8 
 
 5 
 
 4 
 
 
 6 
 
 
 424 
 
 4 
 
 1 Ool Press . . 
 
 4 
 
 l s/ n 
 
 
 
 
 I'K 
 
 
 
 
 1 
 
 
 
 X 
 
 2 Ool Press 
 
 
 2 
 
 
 
 4 
 
 
 2 Ji 
 
 
 
 9 
 
 
 
 
 3 Ool Press 
 
 
 2% 
 
 
 
 
 5M 
 
 4^ 
 
 
 
 
 
 
 94 
 
 1 Ool. Wall 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 Pressed 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 73. Amount of Surface Presented by Various Radiators: 
 
 Table X, gives, according to the columns and heights, 
 
HOT WATER AND STEAM HEATING 87 
 
 the number of square feet of heating surface per section 
 in cast and pressed radiators. This table will be found to 
 present, in very compact form, the similar and much more 
 extended tables in the various manufacturers' catalogs. 
 An approximate rule supplementing this table and giving, 
 to a very fa^r degree of accuracy, the square feet of aur- 
 face in any standard radiator section, is as follows: mul- 
 tiply the height of the section in inches by the number of 
 columns and divide by the constant 20. The result is the 
 square feet of radiating surface per section. The rule ap- 
 plies with least accuracy to the one column radiators. 
 
 74. Hot Water Heaters: Heaters for supplying the hot 
 water to a heating system may be divided into three classes: 
 the round vertical, for comparatively small installations; 
 the sectional, for plants of medium size; and the water tube 
 or flre tube heater with brick setting for the larger in- 
 stallations and for central station work. The round and 
 sectional types usually have a ratio between grate and 
 heating surface of 1 to 20, while the water tube or fire tube 
 heater will have, as an average, 1 to 40. Many different 
 arrangements of heating surface are in use to-day, every 
 manufacturer having a product of particular merit. Trade 
 catalogs supply the most up-to-date literature on this 
 subject, but cuts of each of the types mentioned above may 
 be found in Pig. 38. 
 
 75.. Steam Boilers: The products of many manufac- 
 turers show but little difference between the hot water 
 heater and the steam boiler. The latter is usually supplied 
 with a somewhat larger dome to give greater steam stor- 
 age capacity. For heating purposes, steam boilers fall 
 into the same three classes as mentioned under water heat- 
 ers, having about the same ratio of heating surface to grate 
 surface. With the steam boiler generating steam at, say, 
 5 pounds gage, the temperature on one side of the heating 
 surface is about 227 degrees, while in a water heater the 
 temperature on the same side is about 180 degrees. Hence, 
 with the same temperature of the burning gases, the tem- 
 perature difference is greater in a water heater than in a 
 boiler, resulting in a more rapid transfer of heat, and a 
 correspondingly greater efficiency. 
 
 76. Combination Systems: What are known as com- 
 bination systems are frequently used, principally the one 
 
HEATING AND VENTILATION 
 
 which combines warm air heating with either steam or 
 hot water. For such a system there is needed a combina- 
 tion heater, as shown in Fig. 19. It consists essentially of a 
 furnace for supplying warm air to some rooms, the down- 
 stairs of a residence, for instance, and contains also a coil 
 
 Fire Tube Type 
 Fig. 38. 
 
HOT WATER AND STEAM HEATING 89 
 
 for furnishing hot water to radiators located in other rooms, 
 say, on the upper floors, or in places where it would be 
 difficult for air to be delivered. Considerable difficulty has 
 been encountered in properly proportioning the heating sur- 
 face of the furnace to that of the hot water heater, and the 
 systems have not come into general use. 
 
 77. Fittings: Common and Special: Couplings, elbows 
 and tees, especially for hot water work, should be so formed 
 as to give a free and easy sweep to the contents. It is 
 highly desirable in hot water work to use pipe bends of a 
 radius of about five pipe diameters, instead of the common 
 elbow. In either case all pipe ends should be carefully 
 reamed of the cutting burr before assembling. This is 
 most important, as the cutting burr is sometimes heavy 
 enough to reduce the area of the pipe by one-half, thus 
 creating serious eddy currents, especially at the elbows. 
 If the single main hot water system be installed, great 
 care should be used to plan the mains in the shortest and 
 most direct routes, and the special fittings described and 
 shown in Art. 64 should be used. 
 
 What are known as eccentric reducing fittings are often 
 of value in avoiding pockets in steam lines. Fig. 39 shows 
 
 Fig. 39. 
 
 types of these, which should always be used when, by re- 
 duction or otherwise, a horizontal steam pipe would pre- 
 sent a pocket for the collection of condensation with its re- 
 sultant water hammer. 
 
 Valves for either steam or hot water should be of the 
 gate pattern rather than the globe pattern. The latter is 
 objectionable in hot water systems because of the resistance 
 offered the stream of water, due to the fact that the axis 
 of the valve seat opening is perpendicular to the axis of 
 the pipe connected. The globe valve is objectionable in a 
 steam system because of the fact that in a horizontal run 
 
90 
 
 HEATING AND VENTILATION 
 
 of pipe it forms very readily a pocket for the collection 
 of condensation, thus often producing a source of water 
 hammer. In every way gate valves are preferable, for, as 
 shown in Fig. 40, they present a free opening'without turns. 
 
 The same caution applies 
 in the use of check valves. 
 Swing checks should al- 
 ways be specified rather 
 than lift checks, for the 
 former offer much less re- 
 sistance to the passage of 
 the hot water, or the 
 steam and condensation, as 
 the case may be. P ig. 41 
 
 Fig. 40. 
 
 shows a lift check and a 
 swing check. 
 
 To avoid the annoyance so often experienced by leaky 
 packing around valve stems, there have been designed and 
 
 Fig. 41. 
 
 placed on the market various forms of packless valves. 
 These are to be especially recommended for vacuum work, 
 as the old style valve with its packed stem is, perhaps, the 
 cause of more failures of vacuum systems 
 than any other one item. Fig. 42 shows a 
 section of this type of valve using the 
 diaphragm as the flexible wall. All pack- 
 less valves will be found to use a dia- 
 phragm of -one form or another. 
 
 Quick - opening Valves, or butterfly 
 valves, are much used on hot water radi- 
 ators; one quarter turn of the wheel or 
 handle provided serves to open these full 
 Fig. 42. and, when closed, they are so arranged that 
 
HOT WATER AND STEAM HEATING 
 
 91 
 
 a small hole through the valve permits just enough leakage 
 to keep the radiator from freezing. Special radiator valves 
 for steam are also to be obtained. 
 
 Air valves have a most important function to discharge. 
 As the air accumulates above the water or steam in the 
 
 Fig. 43. 
 
 radiators, its removal becomes absolutely necessary, if all 
 of the radiating surface is to remain effectual. For this 
 purpose small hand valves or pet cocks, Fig. 43, are in- 
 serted near the top of the end section in all hot water 
 work; and either these same valves or automatic ones are 
 inserted for steam work. Valves are not as essential on 
 two-pipe steam systems as on water or single-pipe steam 
 systems, yet are generally used. For steam the air valve 
 should be about one-third the radiator height from the top. 
 
 Fig. 44 shows a common type 
 of automatic air valve using the 
 principle of the expansion stem. As 
 long as the air flows around the 
 stem and exhausts, the stem re- 
 mains contracted, and the needle 
 valve open; but when the hot steam 
 enters and flows past the expansion 
 
 stem, it lengthens sufficiently to close the needle valve. In 
 other forms of air valves the heat of the steam closes the 
 needle valve by the expansion of a volatile liquid in a small 
 closed retainer. In still other forms the lower part of the 
 valve casing is filled with water of condensation upon 
 which floats an inverted cup, having air entrapped within. 
 This cup carries the needle of the valve at its upper ex- 
 tremity, the heat of the steam expanding the air sufficiently 
 to raise the cup and close the valve. Where the system Is de- 
 signed to act as a gravity installation, special air valves must 
 be used which will not allow air to enter at any time. Fig. 
 
92 HEATING AND VENTILATION 
 
 45 shows a type of automatic valve designed to accommo- 
 date larger volumes of air with promptness, 
 as when a long steam main or large trap is 
 to be vented. This type employs a long cen- 
 tral tube, as shown, which carries at the top 
 the valve seat of the needle valve. The 
 needle itself is carried by the two side rods. 
 As long as the air flows up through the 
 central pipe, the needle valve will remain 
 open; but when hot steam enters the tube, 
 it expands, and carries the valve seat up- 
 ward against the needle, thus closing the 
 valve. The size and strength of parts makes 
 this form a very reliable one. 
 
 The expansion tank, Fig. 46, for a hot wat- 
 er system is often located in the bath room or 
 closet near the bath room and its overflow 
 connected to proper drainage. It should be 
 at least 2 feet above the highest radiator. 
 The connection to the heating system mains 
 is most often by a branch from the nearest 
 radiator riser, or it may have an independ- 
 ent riser from the basement flow main. The 
 capacity of the tank is usually taken at 
 about one-twentieth of the volume of the 
 entire system, or a more easily applied rule 
 is to divide the total radiation by 40 to ob- 
 tain the capacity of the tank in gallons. 
 
 Fig. 45. 
 
 See Table 33, Appendix. 
 
 Figr. 46. 
 
CHAPTER VIII. 
 
 HOT WATER AND STEAM HEATING. 
 
 PRINCIPLES OF THE DESIGN, WITH APPLICATION. 
 
 In a hot water or steam system, the first important 
 item to be determined by calculation is the amount of 
 radiation, in square feet, to be installed in each room. 
 Nearly all other items, such as pipe sizes, boiler size, grate 
 area, etc., are estimated with relation to this total radia- 
 tion to be supplied. The correct determination, then, of 
 the square feet of radiation in these systems is all-im- 
 portant. 
 
 78. Calculation of Radiator Surface: Considering the 
 standard room of Chapter III, where the heat loss was de- 
 termined to be 14000 B. t. u. per hour on a zero day, the 
 problem is, to find what amount of surface and what size of 
 radiator will deliver to the room, under the conditions as 
 given, just about 14000 B. t. u. per hour. Experiments by 
 numerous careful investigators have shown that the ordin- 
 ary cast iron radiator, located within the room and sur- 
 rounded with comparatively still air, gives off heat,a,t the 
 rate of 1.7 "B. t. u. (1.6 to 1.8, or 1.7 averag&) per tfegree 
 difference between the temperature of the surrounding air 
 and the average temperature of the heating medium, per 
 hour. This is called the rate of transmission. With hot 
 water the average conditions within the radiator have 
 been found to be as follows: temperature of the water en- 
 tering the radiator 180 degrees; leaving the radiator 160 
 degrees; hence, the average temperature at which the in- 
 terior of the radiator is maintained is 170 degrees. Since, 
 in this country, the standard room temperature is 70 de- 
 grees, and, for hot water, the "degree difference" is 170 
 70 = 100, then a hot water radiator will give off under 
 standard conditions 1.7 X 100 = 170 B. t. u. per hour. The 
 temperature within a steam radiator carrying steam at 
 pressures varying between 2 and 5 pounds gage is usually 
 taken at 220 degrees, and the total transmission is approx- 
 imately 1.7 X (220 70) = 255 B. t, u. per square foot per 
 
94 HEATING AND VENTILATION 
 
 hour. The general formula for the square feet of radiation, 
 then, is 
 
 R _ Total B. t. u. lost from the room per hour 
 
 1.7 (Temp. diff. between inside and outside of rad.) 
 
 For hot water, direct radiation heating, this becomes, to the 
 nearest thousandth 
 
 H 
 
 Rw = .006 H (30) 
 
 1.7 (170 70) 
 
 For steam, direct radiation 
 
 H 
 
 R* = .004 H (31) 
 
 1.7 (220 70) 
 
 It will be noticed from (30) and (31) that R w = 1.5 R B which 
 accounts for the practice that some people have of finding 
 all radiation as though it were steam, and then, when hot 
 water radiation is desired, adding 50 per cent, to this 
 amount. 
 
 APPLICATION. From the standard room under considera- 
 tion, formula 30 gives Rw .006 X 14000 = 84 square feet 
 of radiator surface for hot water; and formula 31 gives R$ 
 = .004 X 14000 = 56 square feet of radiator surface for 
 steam. From these values the number of sections of a giv- 
 en type of radiator can be determined by dividing by the 
 area of one section, as explained in the preceding chapter. 
 The length of the radiator may also be found from this 
 same table, by noting the thickness of the sections, and 
 multiplying by their number. 
 
 Formulas 30 and 31 give the standard ratios be- 
 tween the heat loss and direct radiation. If, however, the 
 radiation is installed as direct-indirect, it is quite common 
 practice to increase the amount of direct radiation by 25 
 per cent, to allow for the ventilation losses. On this basis 
 formulas 30 and 31 become, respectively, 
 
 Rw = .0075 H (32) 
 
 R 8 = .005 H (33) 
 
 Duct sizes for properly accommodating the air in direct- 
 indirect heating may be taken from the following. To ob- 
 tain the duct area in square inches, multiply the square 
 feet of radiation by .75 to 1 for steam, and by .5 to .75 
 for hot water. To obtain the amount of air which may be 
 expected to enter and pass through the radiator into the 
 
HOT WATER AND STEAM HEATING 95 
 
 room, multiply the square feet of radiation by 100 for 
 steam, or by 75 for hot water. This gives the cubic feet of 
 air entering per hour. 
 
 Again, if the radiation is installed as purely indirect, 
 yet not as a plenum system, it is common to increase the 
 amount of direct radiation by 50 per cent. Now formulas 
 30 and 31 become, respectively, 
 
 R w = .009 H (34)-a 
 
 R a = .006 H (34)-b 
 
 F or proportioning the duct sizes in indirect heating 
 use the following table. To obtain the duct area in square 
 inches, multiply the square feet of radiation installed by 
 
 Steam Hot Water 
 
 First Floor 1.5 to 2.0 1.0 to 1.33 
 
 Second Floor 1.0 to 1.25 .66 to .83 
 
 Other Floors .9 to 1.0 . 6 to .66 
 
 Vent ducts, where provided, are usually taken .8 of the 
 area of supply ducts. Also, for finding the amount of air in 
 cubic feet, which may be reasonably expected to enter 
 under these conditions, Carpenter gives the following: 
 Multiply the square feet of indirect radiation by 
 
 Steam Hot Water 
 First Foor 200 150 
 
 Second Floor 170 130 
 
 Other Floors 150 115 
 
 If this amount of air is insufficient for the desired degree 
 of ventilation, more air must be brought in by correspond- 
 ingly larger ducts, and for each 300 cubic feet additional 
 with steam, or each 200 cubic feet additional with hot 
 water, add one square foot to the radiation surface. 
 
 A steam system may be installed to work at any pres- 
 sure, from a vacuum of, say, 10 pounds absolute, to as high 
 a pressure as 75 pounds absolute. To calculate the prop- 
 er radiation for any of these conditions use formula 31 or 
 its derivatives, and substitute the proper steam tempera- 
 ture in place of 220 degrees. 
 
 In like manner, to find the amount of hot water radi- 
 ation for any other average temperatures of the water 
 than the one given, merely substitute the desired average 
 
96 HEATING AND VENTILATION 
 
 temperature in the place of 170. One point should be re- 
 membered, the maximum drop in temperature as the water 
 passes through the heater will seldom be more than 20 
 degrees, even under severe conditions. More often it will 
 be less, but this value is used in calculations. Again, the 
 temperature of the entering water may be at the boiling 
 point, if necessary, thus causing each square foot of sur- 
 face to be more efficient and consequently reducing the to- 
 tal radiation in the room. To illustrate, try formula 30 
 with a drop in temperature from 210 to 190 degrees and find 
 64 square feet of radiator surface for this room. Since a 
 radiator always becomes less efficient from continued use, it 
 is best to design a system with a lower temperature as 
 given in the formula, and then, if necessary under stress 
 of conditions, this system may be increased in capacity by 
 increasing the water temperature, say, up to the boiling 
 point. 
 
 79. Empirical Formulas: All of the above formulas may 
 be considered as rational and checked by years of experience 
 and application. Many empirical formulas have been de- 
 vised in an attempt to simplify, but the results are always 
 so untrustworthy that the rules are worthless unless used 
 with that discretion which comes only after years of prac- 
 tical experience. Many of these rules are based on the 
 cubic feet of volume heated, without any other allowance, 
 these being given anywhere from one square foot of steam 
 surface per 30 cubic feet of space, to one square foot to 
 100 cubic feet. The extreme variation itself shows the un- 
 reliableness of this method, and under no conditions should 
 it be used for proportioning radiating surface. Various 
 central heating companies, and others, proportion radia- 
 tors for their plants according to their own formulas, 
 among which the following may be noted. 
 
 GWG G W C 
 
 (a) Rw = 1- 1 R* = 1- h 
 
 2 10 60 2 10 200 
 
 2 
 
 (b) Rw = G + .05 W + .01 C R = (G + .05 W + .01 (?) 
 
 (c) Rv> = .75 G + .10 W + .01 C Rs = .5 G + .05 W + .005 C 
 
 It is evident that these are really simplified forms of Car- 
 penter's original formula. When applied to the sitting 
 room, where Carpenter's formula gave, for hot water and 
 
HOT WATER AND STEAM HEATING 97 
 
 steam, 84 square feet and 56 square feet, respectively, (a) 
 gives 85.5 and 63, (b) gives 75 and 50, and (c) gives 82.5 
 and 46 respectively. 
 
 Another approximate rule devised by John H. Mills 
 and still used to some extent is "Allow 1 square foot of 
 steam radiation for every 200 cubic feet of volume, 1 square 
 foot for every 20 square feet of exposed wall and 1 square 
 foot for every 2 square feet of exposed glass." Applying 
 this to the standard room, it gives 9.75 -f- 13.25 + 18 = 41 
 square feet of steam radiation as against 56 square feet 
 by rational formula. This shows a considerable difference 
 from the rules preceding. 
 
 80. Greenhouse Radiation: The problem of properly 
 proportioning greenhouse radiation is considered, by some 
 of such special nature as to prohibit the use of theoretical 
 formulas. The fact that the glass area is so large compared 
 to the wall area and the volume, combined with the fact 
 that the head of water in the system is small and that the 
 radiation surface is usually built up as coils from 1&, 1% or 
 2 inch wrought iron pipe, gives rise to a problem that differs 
 essentially from that of a room of ordinary construction. It 
 is not surprising, therefore, to find a great variety of empir- 
 ical formulas designed exclusively for this work. Whatever 
 merit these may have, they do not give the assurance that 
 comes from the application of rational formulas. It is always 
 best to use rational formulas first and then check by the 
 various empirical methods. 
 
 Formulas 30 and 31, stated in Art. 78, when properly 
 modified, are applicable to greenhouses and give very re- 
 liable results. As stated above, the radiating surface Is 
 usually that of wrought iron pipes hung below the flower 
 benches or along the side walls below the glass. The trans- 
 mission constant, K, for wrought iron or mild steel is 2.0 to 
 2.2 B. t. u. per square foot per degree difference per hour, 
 making the total transmission per square foot of coil surface 
 per hour about 2(170 70) = 200 for hot water, and 2(220 
 70) = 300 for steam. These values may be safely used. 
 The only necessary modification of the two formulas men- 
 tioned, consists in replacing the constant 1.7 by 2, giving 
 for hot 
 
98 HEATING AND VENTILATION 
 
 = .005 H (3)-a 
 
 2(170 70) 
 And for steam 
 
 H 
 
 R, = .0033 H (35)-b 
 
 2(220 703 
 
 If, however, the highest temperature at which it is desirable 
 to maintain the house in zero weather is other than 70 de- 
 grees, this temperature should be used instead of 70. 
 
 In a greenhouse there is very little circulation of air, 
 hence the heat loss. H, would be found from the equivalent 
 glass area i. e., (G + .25 TF). Formula (35)-a and b would 
 then reduce to R w = .35 (G + .25 TF) and R s = .23 (G + .25 TF). 
 Because of the fact that the heat loss through the wall is 
 very small compared to that through the glass, some per- 
 sons prefer to drop the last term entirely. If this is done the 
 simple relations, R w = .35 G, and R a .23 G, will be obtained 
 for a greenhouse of maximum temperature of 70 degrees. It 
 is noticed that these values give about one square foot of H. TF. 
 radiation to three square feet of glass area, and one square foot of 
 steam radiation to five square feet of glass area as approximate 
 rules. These figures should be considered a minimum. 
 
 Empirical rules for greenhouse radiation, quoted by 
 many firms dealing in the apparatus, are usually given in 
 the terms of the number of square feet of glass surface 
 heated by one lineal foot of 1% inch pipe. A very commonly 
 quoted and accepted rule is, one foot of 1% inch pipe to 
 every 2^4 square feet of glass, for steam; or, one foot of 
 1% inch pipe to every 1% square feet of glass, for hot water, 
 v\hen the interior of the house is 70 degrees in zero weather. 
 The following table, from the Model Boiler Manual, shows 
 the amount of surface for different interior temperatures 
 and different temperatures of the heating medium. 
 
 In general, it may be said that in greenhouse heating, 
 great care should be used in the rating and the selection 
 
HOT WATER AND STEAM HEATING 
 
 of the boilers or heaters. It is well to remember that the 
 severe service demanded by a sudden change in the weather 
 is much more difficult to meet in greenhouses than in ordin- 
 ary structures, and that a liberal reserve in boiler capacity 
 is highly desirable. 
 
 TABLE XI. 
 
 s 
 
 
 
 
 
 |M 
 
 !! 
 
 H 
 
 400 
 450 
 50 
 550 
 600 
 (55 
 70 
 75 
 800 
 85 
 
 Temperature of Water in Heating Pipes 
 
 Steam 
 
 140 
 
 1600 
 
 1800 
 
 2000 
 
 Three Ibs. 
 Pressure 
 
 Square feet of glass and its equivalent proportioned to 
 one square foot of surface in heating pipes or radiator 
 
 4.33 
 8.63 
 8.07 
 gKfr.98 
 
 2.19 
 1.86 
 1.58 
 1.37 
 1.16 
 .99 
 
 5.25 
 4.65 
 3.92 
 3-89 
 2-89 
 2.53 
 2.19 
 1.92 
 1.63 
 1.42 
 
 6-66 
 5-55 
 4-76 
 4.16 
 8.63 
 3.22 
 2.81 
 2-5 
 2.17 
 1.92 
 
 7.69 
 6.66 
 5.71 
 5. 
 4.83 
 3.84 
 8-44 
 3.07 
 2.78 
 2.46 
 
 8. 
 7-5 
 7. 
 6.5 
 6. 
 5.5 
 5. 
 4.5 
 4. 
 3.5 
 
 This table is computed for zero weather; for lower 
 temperatures add iy a per cent, for each degree below zero. 
 
 81. The Determination of Pipe Sizes: The theoretical 
 determination of pipe sizes in hot water and steam systems 
 has always been more or less unsatisfactory, first, because 
 of the complicated nature of the problem when all points 
 having a bearing upon the subject are considered, and 
 second, because it is almost an impossibility to even ap- 
 proximate the friction offered by different combinations and 
 conditions of piping. The following rather brief analysis 
 gives a theoretical method for determining pipe sizes where 
 friction is not considered. 
 
 In a hot water system let the temperatures of the water 
 entering and leaving the radiator be, respectively, 180 
 and 160 degrees; then it is evident that one pound of the 
 water in passing through the radiator, gives off 20 B. t. u. 
 Under these conditions the standard room would have 14000 -f- 
 20 = 700 pounds of water passing through the radiator per 
 hour. Converting this to gallons, it is found to be 84.03. 
 But the radiation for this room was found to be 84 square 
 feet. Whence, it may be said that a hot water radiator 
 
100 ^ HEATING AND VENTILATION 
 
 under normal conditions of installation and under heavy 
 service requires one gallon of water per square foot of sur- 
 face per hour. Knowing the theoretical amount of water 
 per hour, it remains only to obtain the theoretical speed 
 at which it travels, due to unbalanced columns, to obtain 
 finally, by division, the theoretical area of the pipe. 
 
 Consider a radiator to be about 10 feet above the 
 source of heat, and the temperature in the flow riser to be 
 180 degrees and in the return riser 160 degrees, good values 
 in practice. Now, the heated water in the -flow riser 
 weighs 60.5567 pounds per cubic foot, while that in the 
 return riser weighs 60.9697 pounds per cubic foot. The mo- 
 
 / W W \ 
 tive force is f = g [ ) where g is the acceleration 
 
 \ w + wJ 
 
 due to gravity, W is the specific gravity (weight) of the 
 cooler column and W is the specific gravity (weight) of the 
 warmer column. Substitute / for g in the velocity formula 
 and obtain v = fafh and 
 
 / / W W \ 
 
 v =-/ 2gh( ) (36) 
 
 \ \W + W / 
 
 Inserting values W, W and assuming h = 10 feet, we have 
 
 v = V2 X 32.2 X 10 X .0034 = V 2 -1896 = 1.47 feet per second. 
 From this, it has become a custom to speak of 1.5 feet per 
 second or 5400 feet per hour, as the theoretical velocity of 
 water in, say, a first floor riser, disregarding the effect of 
 all friction and horizontal connections. Theoretical veloci- 
 ties for any other height of column and for other temper- 
 atures may be obtained in like manner. Continuing this 
 special investigation and changing the 84 gallons per hour 
 to cubic inches per hour by multiplying by 231, the internal 
 pipe area may be obtained by dividing by the unit speed 
 per hour which gives (84 X 231) + (5400 X 12) = .3 square 
 inch. This corresponds to approximately a % inch pipe 
 and without doubt, would supply the radiator if the sup- 
 position of no frictional resistances could be realized. This 
 ideal condition, of course, cannot be had, nor can the fric- 
 tion in the average house heating plant be theoretically 
 treated with any degree of satisfaction. Hence it is still 
 the custom to use tables for the selection of pipe sizes, 
 
HOT WATER AND STEAM HEATING 101 
 
 based upon what experience has shown to be good practice. 
 Such tables, from various authorities, may be found in the 
 Appendix. It is safe to say that one should never use any- 
 thing- smaller than a 1 inch pipe in low pressure hot water 
 work. 
 
 With steam systems, where the heating medium is a vapor, 
 and subject in a lesser degree to friction, the discrepancy 
 between the theoretical and the practical sizes of a pipe 
 is not so great as in hot water. Each pound of steam, in 
 condensing, gives off approximately 1154 181 = 973 B. t. u. 
 To supply the heat loss of the standard room, 14000 B. t. u. 
 per hour, it would require 14.5 pounds of steam per hour. 
 When it is remembered that the calculated surface of the 
 direct steam radiator for this room was 56 square feet, it 
 appears that a radiator, under stated conditions and under a 
 heavy service, requires one-fourth of a pound of steam per square 
 foot of surface per hour. This may be shown in another way: 
 each square foot of steam radiation gives off 255 B. t. u. 
 per hour; then, each square foot will condense 255 -j- 973 =: 
 .26 + pounds of steam per hour. 
 
 Now the volume of the steam per pound at the usual 
 steam heating pressure, 18 pounds absolute, is 21.17 cubic 
 feet. Since the standard room radiator required 14.5 pounds 
 per hour, it would, in that time, condense steam corres- 
 ponding to a void of 21.17 X 14.5 307 cubic feet per hour. 
 This is the volume of the steam required by the radiator, 
 and, if the speed of the steam in the pipe lines be taken 
 at 15 feet per second, or 54000 feet per hour, the area of 
 the pipe would be 307 X 144 -7- 54000, or .82 square inch, 
 corresponding very closely to a 1 inch pipe. For a two- 
 pipe system this would be considered good practice under 
 average conditions; but in a one-pipe system, where the 
 condensation is returned against the steam in the same 
 pipe that feeds, a pipe one size larger would be taken. 
 
 Table 33, Appendix, calculated from Unwin's formula, 
 may be used in finding sizes and capacities of pipes carrying 
 steam. In addition to this, Tables 26, 27, 28 and 29 give sizes 
 that are recommended by experienced users. 
 
 For a theoretical discussion of loss of head by friction 
 in hot water and steam pipes, see Arts. 144 and 172. 
 
 82. Grate Area: To obtain the grate area for a direct 
 radiation hot water or steam system by the B. t. u. method, 
 
102 HEATING AND VENTILATION 
 
 the same analysis as found in Chapter IV, may be applied. 
 The total B. t. u. heat loss, H, is that calculated by the 
 formula and does not include Hv, the heat loss due to ven- 
 tilation, since with the direct hot water or steam system as 
 usually installed no ventilation is provided. In any special 
 case where ventilation is provided in excess, use E r instead 
 of H. The commercial rating of heaters and boilers is a 
 subject each day receiving greater attention at the hands 
 of manufacturers; yet it is a subject where much uncer- 
 tainty is felt to exist. Hence the recommendation, "Always 
 check grate area by an actual calculation," rather than rely 
 entirely upon the catalog ratings. 
 
 83. Pitch of Mains: The pitch of the mains is quite as 
 important in hot water as in steam work. This should not 
 be less than 1 inch in 10 feet for hot water systems, and not 
 less than 1 inch in 30 feet for steam systems. Greater 
 pitches than these are desirable, but not always practic- 
 able. In hot water plants the pitch of the basement mains, 
 whether flow or return, is upward as these mains extend 
 from the source of heat, that is, the highest point is the 
 farthest from the heater. In steam plants the mains, under 
 any condition of arrangement, always pitch downward 
 in the direction of the flow of the condensation. 
 
 84. Location and Connection of Radiators: In locat- 
 ing radiators, it is best to place them along the outside or 
 the exposed walls. When allowable, under the windows 
 seems to be a favorite position. Especially in buildings 
 of several stories, the radiators should be arranged, where 
 possible, in tiers, one vertically above another, thus re- 
 ducing the number of and avoiding the offsets in the risers. 
 In the one-pipe system any number of radiators may be con- 
 nected to the same riser. In the two-pipe system several 
 radiators may have either a common flow riser, or a common 
 return riser, but should never have both, either with hot 
 water or with steam. 
 
 The connections from the risers to the radiators should 
 be slightly pitched for drainage and are usually run along 
 the ceiling below the radiator connected. These connections 
 should be at least two feet long to give that flexibility of 
 connection to the radiator made necessary by the expan- 
 
HOT WATER AND STEAM HEATING 103 
 
 sion and contraction of the long riser. Similarly, all risers 
 should be connected to the mains in the basement by hori- 
 zontals of about two feet to allow for the expansion and 
 contraction of the mains. A system thus flexibly connected 
 stands in much less danger of developing leaky joints than 
 does one not so connected. For sizes of radiator connections 
 see Table 24, Appendix. 
 
 85. General Application: Figs. 48, 49 and 50 show the 
 typical layout of a hot water plant. Due to the similarity be- 
 tween hot water and steam installations, the former only will 
 be designed complete. In attempting the layout of such a 
 system, the very first thing to be done is to decide at what 
 points in the rooms the radiators should be placed. This 
 should be done in conjunction with the owner as he may 
 have particular uses for certain spaces from which radia- 
 tors are hence excluded. The first actual calculation should 
 be the heat loss from each room, with the proper exposure 
 losses, and the results should be tabulated as the first 
 column of a table similar to Table XII. In the 
 example here given, this loss is the same as, and taken 
 from, the table of computations for the furnace work, Art. 
 48, the house plans being identical. The second column 
 of Table XII, as indicated, is the square feet of radiation; 
 and since this is a hot water, direct radiation system, it 
 is obtained by taking .006 of the items in the first column 
 according to formula 30. Knowing this, a type and 
 height of radiator can be selected, and the number of 
 sections determined by Table X. Next obtain the lengths 
 of radiators by multiplying the number of sections by the 
 total thickness of the sections, as given in Table X, and 
 determine whether or not the radiator of such a length 
 will fit into the chosen space. If not, then a radiator of 
 greater height and larger surface per section must be 
 selected. Riser sizes and connections may be taken ac- 
 cording to Tables 26 and 24 respectively. The column of 
 Table XII headed "Radiators Installed" gives first the num- 
 ber of sections; second, the height in inches; and third, the 
 number of columns or type of the section. 
 
 Locate radiators on the second floor and transfer the 
 location of their riser positions to first floor plan, then to 
 the basement plan. Locate radiators on the first floor and 
 
104 HEATING AND VENTILATION 
 
 transfer their riser locations to the basement plan, which 
 will then show, by small circles, the points at which all 
 risers start upward. This arrangement will aid greatly in 
 the planning of the basement mains. 
 
 The keynotes in the layout of the basement mains 
 should be simplicity and directness. If the riser positions 
 show approximately an even distribution all around the 
 basement, it may be advisable to run the mains in 
 complete circuits around the basement. If, again, the 
 riser positions show aggregation at two or three localities, 
 then two or three mains running directly to these localities 
 would be most desirable. As an example, take the applica- 
 tion shown here. The basement plan shows three clusters 
 of riser ends, one under the kitchen, another under the 
 study, and a third on the west side of the house. This 
 condition immediately suggests three principal mains, as 
 shown. The main toward the kitchen supplies the bath, 
 chamber 4 and the kitchen, making a total of 131 square 
 feet. Being only about 13 feet long, it would readily carry 
 this radiation if of 2 inch diameter. See Table 29. The 
 main to the study and the hall supplies chamber 1, the hall 
 and the study, making a total of 221 square feet, which 
 can be carried by a 2% inch pipe. The main to the west side 
 of the house supplies chamber 2, chamber 3, the sitting room 
 and the dining room, a total of 249 square feet, which would 
 almost require a 3 inch main, according to the table, were 
 it not for its comparatively short length. A 2^ inch pipe 
 would amply supply this condition. 
 
 In hot water work, as well as in steam, it is customary 
 to take the connections to flow risers from the top of the 
 mains, thus aiding the natural circulation, Fig. 31. If not 
 taken directly from the top of the main, it is often taken at 
 about 45 degrees from the top. This arrangement, with a 
 short nipple, a 45 degree elbow, and the horizontal connec- 
 tion about 1% to 2 feet long, makes a joint of sufficient 
 flexibility between the main and riser to avoid expansion 
 troubles. 
 
 In the selection of a heater or boiler much that has 
 been said concerning furnaces applies. The heater or boiler 
 should, above all, have ample grate area, checked on a B. 
 t. u. basis, and should have a sufficient heating surface so 
 
HOT WATER AND STEAM HEATING 
 
 105 
 
 designed that the heated gases from the fire impinge per- 
 pendicularly upon it as often as may be without seriously 
 reducing the draft. As shown by the total of the radiation 
 column, a hot water boiler should be selected of such rated 
 mains and risers. Since this loss is usually taken from 
 20 to 30 per cent., depending upon the thoroughness with 
 which the basement mains are insulated, the heater for this 
 house should have a rated capacity of not less than 720 
 square feet of radiation. 
 
 TABLE XII. 
 
 
 | 
 
 1* 
 
 Radiators 
 installed 
 
 Lengths 
 ofRad'or 
 installed 
 
 Riser 
 Sizes 
 
 II 
 
 
 o"S 
 
 
 
 
 
 
 
 
 *- *-* 
 
 
 
 g 
 
 "0 
 
 
 d 
 
 
 
 
 
 
 
 tsS 
 
 \\ 
 
 1 
 
 g 
 
 1 
 
 
 is 
 
 s 
 
 il 
 
 
 hS 
 
 & 
 
 
 
 3 
 
 * 
 
 S 
 
 o 
 
 "S3 
 
 *a 
 
 
 ffii: 
 
 & 
 
 
 
 o 
 
 
 
 ^ 
 
 c 
 
 rt 
 
 
 Sitting R 
 
 14000 
 
 84 
 
 15-82-3 
 
 14-44-3 
 
 34 
 
 42 
 
 1* 
 
 i^ 
 
 1 
 
 Dining R. 
 
 10800 
 
 65 
 
 14-26-3 
 
 18-26-3 
 
 32 
 
 54 
 
 1% 
 
 1J4 
 
 IK 
 
 Study 
 
 13250 
 
 80 
 
 82-14-3 
 
 20-14-P 
 
 72 
 
 60 
 
 
 1V4 
 
 1% 
 
 Kitchen 
 
 11900 
 
 70 
 
 12-82-3 
 
 8 -45-4 
 
 
 24 
 
 1H 
 
 1H 
 
 l>i 
 
 Rec'p'n Hall 
 
 14000 
 
 84 
 
 15-82-3 
 
 14-44-8 
 
 84 
 
 42 
 
 i^ 
 
 1V4 
 
 
 Chamber 1 
 
 9400 
 
 57 
 
 18-26-3 
 
 16-26-3 
 
 30 
 
 48 
 
 iM 
 
 IK 
 
 IX 
 
 Chamber 2 
 
 9850 
 
 60 
 
 13-26-3 
 
 16-26-3 
 
 30 
 
 48 
 
 1% 
 
 1M 
 
 IX 
 
 Chambers 
 
 6600 
 
 40 
 
 10-26-3 
 
 12-26-3 
 
 23 
 
 36 
 
 i 
 
 1 
 
 1 
 
 Chamber 4 
 
 5600 
 
 35 
 
 10-26-3 
 
 12-26-8 
 
 28 
 
 36 
 
 i 
 
 1 
 
 1 
 
 Bath... 
 
 4400 
 
 
 6-26-3 
 
 7-26-3 
 
 14 
 
 21 
 
 j 
 
 1 
 
 j 
 
 "I 
 
 
 
 
 
 
 
 
 leoi 
 
 
 
 
 
 
 
 
166 
 
 HEATING AND VENTILATION. 
 
 4Lr 
 
 *JL_t ttfia-Zft- 
 
 I --- L, 15' 9i" - ifjl^'j. - 9' - Sir 
 
 - ---- ** ^ 
 
 J 
 
 PLAM 
 
 Ceiling 6 ' 
 
 Fig. 48. 
 
HOT WATER AND STEAM HEATING 107 
 
 fipoR. PLAN 
 Ceiling /O ' 
 
 Fig. 49. 
 
108 
 
 HEATING AND VENTILATION 
 
 5ttohD riPOR. PLAN 
 
 Ceiling $' 
 
 , Fig. 60. 
 
HOT WATER AND STEAM HEATING 109 
 
 86. Insulating: Steam Pipes: In all heating systems, 
 pipes carrying steam or water should be insulated to protect 
 from heat losses, unless these pipes are to serve as radiating 
 surfaces. In a large number of plants the heat lost through 
 these unprotected surfaces, if saved, would soon pay for 
 first class insulation. The heat transmitted to still air 
 through one square foot of the average wrought iron pipe 
 is from 2 to 2.2 B. t. u. per degree difference of temperature 
 between the inside and the outside of the pipe. Assuming 
 the minimum value, and also that the pipe is fairly well 
 protected from air currents, the heat loss is, with steam at 
 100 pounds gage and 80 degrees temperature of the air, 
 (338 80) X 2 = 516 B. t. u. per hour. With steam at 50, 
 25, and 10 pounds gage respectively this will be 436, 374 and 
 320 B. t. u. If the pipe were located in moving air, this loss 
 would be much increased. It is safe to say that the average 
 low pressure steam pipe, when unprotected, will lose be- 
 tween 350 and 400 B. t. u. per hour. Taking the average of 
 these two values and applying it to a six inch pipe 100 feet 
 in length, for a period of 240 days at 20 hours a day, we have 
 a heat loss of 171 X 375 X 240 X 20 = 307800000 B. t. u. With 
 coal at 13000 B. t. u. per pound and a furnace efficiency of 60 
 per cent, this will be equivalent to 39461 pounds of coal, 
 which at $2.00 per ton will amount to $39.46. From tests 
 that have been run on the best grades of pipe insulation, it is 
 shown that 80 to 85 per cent, of this heat loss could be 
 saved. Taking the lower value we would have a financial 
 saving of $31.56 where the covering is used. Now if a good 
 grade of pipe covering, installed on the pipe, is worth $35.00, 
 the saving in one year's time would nearly pay for the 
 covering. 
 
 To be effective, insulation should be porous but should 
 be protected from air circulation. Small voids filled with 
 still air make the best insulating material. Hence, hair 
 felt, mineral wool, eiderdown and other loosely woven ma- 
 terials are very efficient. Some of these materials, however, 
 disintegrate after a time and fall to the bottom of the pipe, 
 leaving the upper part of the pipe comparatively free. Many 
 patented coverings have good insulating qualities as well as 
 permanency. Most patented coverings are one inch in thick- 
 ness and may or may not fit closely to the pipe. A good ar- 
 
110 
 
 HEATING AND VENTILATION 
 
 rangement is to select a covering one size larger than the 
 pipe and set this off from the pipe by spacer rings. This 
 air space between the pipe and the patented covering is a 
 good insulator in itself. Table 35, Appendix, gives the 
 results of a series of experiments on pipe covering, obtained 
 at Cornell University under the direction of Professor Car- 
 penter. These values are probably as nearly standard as 
 may be had. 
 
 87. "Water Hammer: When steam is admitted to a cold 
 pipe, or to a pipe that is full of water, it is suddenly con- 
 densed and causes a sharp cracking noise, that under certain 
 conditions may become so severe as to crack the fittings and 
 open up the joints. The noise is produced by the sudden rush 
 of water in an endeavor to fill the vacuum produced by the 
 condensed steam. Steam at atmospheric pressure occupies 
 1644 times the volume of the water that produced it, hence, 
 by suddenly condensing it, a very high vacuum may be 
 produced. This action causes a relatively high velocity in 
 any body of water adjacent to it. The worst condition is 
 found when a quantity of steam enters a pipe filled with 
 water. Condensation suddenly takes place and the two 
 bodies of water come together with high velocity causing 
 severe concussion. Steam should always be admitted to a 
 cold pipe, or to one filled with water, very slowly. 
 
 88. Returning the Water of Condensation, in a Low 
 Pressure Steam Heating System, to the Boiler: In re- 
 
 Eig. 51. Fig. 52. 
 
 turning the water of condensation to the boiler four methods 
 are in use; gravity, steam traps, steam loops and steam 
 pumps. The gravity system is the simplest and is used in all 
 cases where the radiation is above the level of the boiler and 
 
HOT WATER AND STEAM HEATING 111 
 
 where the boiler pressure is used in the mains. In a gravity 
 return, no special valves or httings are necessary, but a free 
 path with the least amount of friction in it is provided be- 
 tween the radiators and a point on the boiler below the water 
 line. No traps of any kind should be placed in this return 
 circuit. 
 
 When the radiation is below the water line, or where the 
 pressure in the mains is less than that in the boiler, some 
 form of steam-trap must be put in with special provision for 
 returning this water to the boiler. Two kinds of traps may 
 be had, low pressure and high pressure. The first is well 
 represented by the bucket trap, Fig. 51, and the second, by 
 the Bundy trap, Fig. 52. The action of these traps is as 
 follows: Bucket trap. Water enters at D and collects 
 around the bucket, which is buoyed up against the valve. 
 The water collects and overflows the bucket until the com- 
 bined weight of the water and bucket overbalances the 
 buoyancy of the water. The bucket then drops and the 
 steam pressure upon the inside, acting upon the surface of 
 the water, forces it out through the valve and central stem 
 to the outlet B. When a certain amount of this water has 
 been ejected, the bucket again rises and closes the valve. 
 This action is continuous. Bundy trap. Water enters at D 
 through the central stem and collects in the bowl A, which 
 is held in its upper position by a balanced weight. When 
 the water collects in the bowl sufficiently to lift the weight, 
 the bowl drops, the valve E opens, and steam is admitted 
 to the bowl, thus forcing the water out through the curved 
 pipe and the valve E. This action is continuous. 
 
 Each trap is capable of lifting the water approximately 
 2.4 feet for each pound of differential pressure. Thus, for a 
 pressure of 5 pounds gage within the boiler and 2 pounds 
 gage on the return, the water may be lifted 7 feet above 
 the trap, or say, to the top of an ordinary boiler. This is not 
 sufficient, however, to admit the water into the boiler 
 against the pressure of the steam. A receiver should be 
 placed here to catch the water from the separating trap 
 and deliver it to a second trap above the boiler which, in 
 turn, feeds the boiler. Live steam is piped from the boiler 
 to each trap, but the steam supply to the lower trap is 
 
112 
 
 HEATING AND VENTILATION 
 
 throttled, to give only enough 
 pressure to lift the water 
 into the receiver. A system 
 connected up in this way is 
 shown in Fig. 53. Traps 
 which receive the water of 
 condensation for the pur- 
 pose of feeding the boiler 
 are called return traps and 
 sometimes work under a 
 higher pressure' of steam 
 than the separating traps. 
 Many different kinds of traps 
 are in general use but these 
 will illustrate the principle 
 of returning the condensation 
 to the boiler. 
 
 A very simple arrangement, and yet a very difficult one 
 to operate satisfactorily, is by the use of the steam loop, Fig. 
 54. The water of condensation from the radiators drains 
 to the receiver A, which is in direct communication with the 
 riser B. The drop leg D, being in communication with the 
 boiler through a check valve which opens toward the boiler 
 at the lowest point, is filled with water to the point X, suffi- 
 ciently high above the water line of the boiler that the 
 static head balances the differential pressure between the 
 steam in the boiler and that in the condenser. The horizon- 
 tal run of pipe C serves as a condenser and, in producing a 
 partial vacuum, lifts the water from the receiver. This 
 water is not lifted as a solid body, but as slugs of water 
 interspersed with quantities of steam and vapor. The water 
 in A is at or near the boiling point and the reduced pressure 
 in B reevaporates a portion of it which, in rising as a 
 vapor, assists in carrying the rest of the water over the 
 goose-neck. When the condensation in D rises above the 
 point X, the static pressure overbalances the differential 
 steam pressure, and water is fed to the boiler through the 
 check. 
 
 To find the location of the point X, above the water line 
 in the boiler, the following will illustrate: Let the pres- 
 sures in the boiler, condenser and receiver be respectively 
 
HOT WATER AND STEAM HEATING 
 
 113 
 
 5, 2 and 4 pounds gage, then the differential pressure between 
 the boiler and condenser is 3 pounds per square inch. If the 
 weight of one cubic foot of water at 212 degrees is 59.76 
 pounds, then the pressure is .42 pounds per square inch for 
 each foot in height. Stated in other words, one pound dif- 
 ferential pressure will sustain 2.4 feet of water. With a 
 pressure difference of 3 pounds,, this gives 3 -r- .42 = 7.2 
 feet from the water level in the boiler to the point X, not 
 taking into account the friction of the piping and check 
 which would vary from 10 to 30 per cent. Assuming this 
 friction to be 20 per cent, we have, 7.2 -^ .80 = 9 feet of head 
 to produce motion of the water. 
 
 Fig. 54. 
 
 The length of the riser pipe B and its diameter, depend 
 upon the differential pressure between the condenser and 
 the receiver, and upon the rapidity of condensation in the 
 horizontal. 
 
 With a differential pressure of 2 pounds this would sus- 
 pend 2X2.4 = 4.8 feet of solid water. The specific gravity, 
 however, of the mixture in this pipe is much less than that 
 of solid water. For the sake of argument let this specific 
 
114 HEATING AND VENTILATION 
 
 gravity be 20 per cent, of that of solid water, then we would 
 have a possible lift, not including friction, of 5 X 4.8 = 24 
 feet. This is 24 9 = 15 feet below the water level in the 
 boiler. The diameter of the riser may vary for different 
 plants, but for any given plant the range of diameters is 
 very limited. These, as has been stated, are usually found 
 by experiment. 
 
 A drain cock should be placed in the receiver at the 
 lowest point. When cold water has collected in the re- 
 ceiver it is necessary to drain this water to the sewer before 
 the loop will work. An air valve should be placed at the top 
 of the goose-neck to draw off the air. If the horizontal pipe 
 is filled with air, there will be no condensation and the loop 
 will refuse to work. Never connect a steam loop to a boiler 
 in connection with a pump or any other boiler feeder. To 
 determine whether a loop is working or not, place the hand 
 on the horizontal' pipe. If this is cold it is not working. 
 
 The last method mentioned for feeding condensation to 
 the boiler was by the use of a steam pump. This is fully dis- 
 cussed in Art. 161. 
 
 89. Suggestions for Operating Hot Water Heaters and 
 Steam Boilers: Before firing up in the morning, examine 
 the pressure gage to see if the system is full of water. If 
 there be any doubt, inspect the water level in the expan- 
 sion tank. If it is a steam system, examine the gage glass 
 and try the cocks to see if there is sufficient water in the 
 boiler. 
 
 See that all valves on the water lines are open. On the 
 steam system try the safety valve to see if it is loose and 
 see if the pressure gage stands at zero. 
 
 Clean the fire and sprinkle over it a small amount of 
 fresh coal. 
 
 Open up the drafts and when the fire is burning well 
 fill up with coal. 
 
 In starting a fire under a cold boiler it should not be 
 forced, but should warm up gradually. 
 
 Hard coal may be thrown evenly over the fire. Soft coal 
 should be banked in front on the grate, until the gases are 
 driven off. It is then distributed back over the fire. 
 
 The thickness of the fire will vary from four inches to 
 one foot depending upon the draft and the kind of coal. 
 
HOT WATER AND STEAM HEATING 115 
 
 Clean the fire when it has burned low, partially closing 
 the drafts while cleaning:. 
 
 In a boiler or heater, using the water over continuously, 
 there will be little need of cleaning out the inside. In a 
 system using fresh water continuously, however, the boiler 
 should be blown off and cleaned about once or twice a month. 
 Never blow off a boiler while hot or under heavy pressure. 
 
 In every system the heater or boiler should be thoroughly 
 overhauled and cleaned before firing up in the fall. 
 
 Keep the ash pit clean and protect the grates from burn- 
 ing out. 
 
 Keep the tubes and gas passages clean and free from soot. 
 
 Inspect the pressure gage, glass gage, water cocks and 
 thermometers frequently. 
 
 In case of low water in a steam system, cover the fire 
 with wet ashes or coal and close all the drafts. Do not 
 open the safety valve. Do not feed water to the boiler. Do 
 not draw the fire. Keep the conditions such as to avoid any 
 sudden shock. After the steam pressure has dropped, draw 
 the fire. 
 
 Excessive pressure may be caused by the sticking of the 
 safety valve in the steam system, or by the stoppage of the 
 water line to the expansion tank in the hot water system. 
 The safety valve should never be allowed to lime up, and the 
 expansion tank should always be open to the heater and to 
 the overflow. 
 
 When leaving the fires for the night, push them to the 
 rear of the grate and bank them as stated in Art. 59. 
 
 References on Hot Water and Steam. 
 
 TECHNICAL BOOKS. 
 
 Snow, Principles of Heat., Chap. IX, X, I. C. S., Prin. of Heat, 
 and Vent. p. 1185, 1091. Monroe, Steam Heat. & Vent., p. 13. Law- 
 ler, Hot Water Heating, p. 19. Carpenter, Heat. & Vent. Bldgs., p. 
 150, 231. Thompson, House Heat, ty (steam & Water, p. 15. Hubbard 
 Power, Heat. & Vent., pages 433, 464, 484, 505, 510. 
 TECHNICAL PERIODICALS. 
 
 Engineering News. Suggestions for Ehx'st Steam Heat, Apr. 
 7, 1904, p. 332. An Improved Steam Heat. System, Thermo- 
 grade System, July 23, 1903, p. 80. Factory System of the 
 United Shoe Machinery Co., W. C. Snow, May 25, 1905, p. 537. 
 Heating a Trolley Car Barn, J. I. Brewer, April 29, 1909, p. 
 462. Engineering Review. Heat. & Vent, of the new Parental 
 Home and School at Flushing, L. L, Jan. 1910, p. 48. A Hot 
 Water System with Radiators and Boiler on the same Level, 
 J. P. Lisk, Aug. 1908, p. 34. A Hot Water Heat. System for 
 a City Residence, J. P. LLsk, June 1909, p. 44. Hot Water 
 Heat. Apparatus in Plymouth Church, Brooklyn, N. Y., Dec. 
 1908, p. 19. Heat., Vent, and Temperature Regulation in the 
 
116 HEATING AND VENTILATION 
 
 Measles Pavilion of the Kingston Ave. Hospital, Brooklyn, 
 N. Y., Jan. 1910, p. 35. Heat, and Vent. Plant of the Boston 
 Safe Deposit and Trust Company's Building, C. L. Hubbard, 
 April 1910, p. 37. Heat, and Vent. Installation in the Burnet 
 St. School, Newark, N. J., Jan. 1909, p. 20. A Unique Low 
 Pressure Steam Heat. Apparatus, Feb. 1909, p. 38. Practical 
 Points on Steam Heating (Direct Heating), C. L. Hubbard, 
 Aug. 1908, p. 29. (Indirect Heat.), Sept. 1908, p. 19. (Exhaust 
 Steam Heat.), Nov. 1908, p. 21. Steam Heating Systems, Wm. J. 
 Baldwin, March 1905, p. 7. Machinery. Shop Heating by Direct 
 Radiation, C. L. Hubbard, July 1910, p. 884. Sizes of Pipe Mains 
 for Hot Water Heating, C. L. Hubbard, Sept. 1909, p. 38. 
 The Railway Review. Heating System of the Scranton St. Rail- 
 way Shops, June 13, 1908, p. 480. Heating of Passenger Trains 
 May 23, 1908, p. 408. The Pennsylvania R. R. System of Heat, 
 and Vent. Passenger Trains, Feb. 22, 1908, p. 157. Vent, and 
 Heating of Coaches and Sleeping Cars, July 18, 1908, p. 586. 
 Hot Water Heating Arrangements for Passenger Stations, Oct. 
 10, 1908, p. 829. Typical Heating Plants, Horace L. Winslow 
 Co., June 18, 1910, p. 596. The Heating & Ventilating Magazine. Res- 
 idence Heating by Direct and Indirect Hot Water, July, 1905, 
 p. 25. Carrying Capacities of Pipes in Low Pressure Steam 
 Heating, Wm. Kent, E eb. 1907, p. 7. Standard Sizes of Steam 
 Pipes, Jas. A. Donnelly, Jan. 1907, p. 21. Formula for Pipe 
 Sizes in Hot Water Heating, Oliver H. Schlemmer, Sept. 1907, 
 p. 9. Co-efficient of Transmission in Cast Iron Radiation, 
 John R. Allen, Aug. 1908, p. 19. Relative Capacities of Pipes, 
 John Jaeger, May 1907, p. 1. Methods of Figuring Radiation, 
 Gerard W. Stanton, Dec. 1907. Computation of Radiating Sur- 
 face, J. Byers Holbrook, Nov. 1904, p. 77. Domestic Engineering . 
 A Practical Manual of Steam and Water Heating. E. R. Pierce, 
 CSeries of Articles), Vol. 51, No. 2, April 9, 1910; Vol. 53, No. 
 9, Nov. 26, 1910. Proportions and Power of Low Pressure 
 Heating Boilers, Vol. 47, No. 11, June 12, 1909, p. 319. How to 
 Install and Cover a Steam or Hot Water Main, "Phoenix," Vol. 
 46, No. 10, March 6, 1909, p. 278. How to Secure Correct Pipe 
 Sizes for Low Pressure Steam Heating, E. K. Munroe, Vol. 45, 
 No. 9, Nov. 28, 1908, p. 243. Rules for Proportioning Indirect 
 Heating Plants, R. T. Crane, Vol. 49, No. 6, Nov. 6, 1909, p. 
 143. Trans. A. #. H. & V. E. Circulation of Hot Water, J. S. 
 Brennan, Vol. XI, p. 93. Residence Heating by Direct and 
 Indirect Hot Water, E. F. Capron, Vol. XI, p. 174. Standard 
 Sizes of Steam Mains, J. A. Donnelly, Vol. XIII, p. 43. The 
 Carrying Capacity of Pipes in Low Pressure Steam Heating, 
 Wm. Kent, Vol. XIII, p. 54. Heating and Ventilating a Group 
 of Public Schools, S. R. Lewis, Vol. XIII, p. 187. The Com- 
 bined Pressure and Vacuum Systems of Steam Heating, G. 
 Hoffman, Vol. XIII, p. 223. Sizes of Return Pipes in Steam 
 Heating Apparatus, J. A. Donnelly, Vol. XII, p. 109. Pro- 
 portioning Hot Water Radiation in Combination Systems of 
 Hot Water and Hot Air Heating, R. C. Carpenter, Vol. VII, 
 p. 132. Tests of Radiators with Superheated Steam, R. C. 
 Carpenter, Vol. VII, p. 185. Relative Economy of Steam, 
 Vapor, Vacuum and Hot Water Heating for Residences, Vol. 
 XII, p. 341. The Relation between the Completeness of Air 
 Removal and the Efficiency of Steam Radiators, Vol. XII, 
 p. 315. Advantage of Low Pressure Hot Water Heating Sys- 
 tems, Vol. XI, p. 183, 209. Measurements of Wall Radiators, 
 Vol. XII, p. 361. Advantages of Standard Dimensions of 
 Radiator Valves and Connections, Vol. XIII, p. 148. The 
 Relative Healthfulness of Direct and Indirect Heating Sys- 
 tems, Vol. XIII, p. 36. Improving the Heating Capacity of a 
 Radiator by an Electric Fan, Vol. VIII, p. 222. 
 
CHAPTER IX. 
 
 MECHANICAL, WARM AIR HEATING AND 
 VENTILATING SYSTEMS. 
 
 DESCRIPTION OF SYSTEMS AND APPARATUS EMPLOYED. 
 
 90. Fire-places, Stoves, Furnaces and Direct Radiation 
 Systems of both steam and hot water have, individually, 
 advantages and disadvantages, but, in common, all lack 
 what is increasingly being considered as of more import- 
 ance than heating, namely, positive ventilation. Merely to 
 heat a poorly ventilated apartment only serves to increase 
 the discomfort of the occupants, and modern legislative 
 bodies are reflecting the opinion of the times by the passage 
 of compulsory ventilation laws affecting buildings with 
 numerous occupants, such as factories, barracks, school 
 houses, hotels and auditoriums. To meet this demand for 
 the positive ventilation of such classes of buildings, there 
 has been developed what is variously known as the hot Mast 
 heating system, plenum system, fan Wast system or mechanical warm 
 air system. 
 
 91. Elements of the Mechanical Warm Air System: 
 
 Known by whatever name, this system contemplates the 
 use of three distinctly vital elements; first, some form of 
 hot metallic surface over which the forced air may pass 
 and be heated; second, a blower or fan of some description 
 to propel the air; and third, a proper arrangement of ducts 
 or passageways to distribute this heated air to desired 
 locations. P igs. 66 and 67 show these essentials, fan, 
 heating coils and ducts in their relative positions with con- 
 nections as found in a typical plant of this system. Many 
 attachments and improved mechanisms may be had to-day 
 in connection with this system, such as air washers and 
 humidifiers, automatic damper control systems, and brine 
 cooling systems whereby the heating coils may be used 
 as cooling coils, and, during hot weather, be made to 
 maintain the temperature within the building from 10 de- 
 
118 
 
 HEATING AND VENTILATION 
 
 grees to 15 degrees lower than the atmosphere. Any of 
 these auxiliaries, however, change in no way the necessity 
 for the three fundamentals named and their general ar- 
 rangement as shown. 
 
 92. Variations in the Design ~f Mechanical Warm Air 
 Systems: With regard to the position of the fan, two 
 methods of installing the system are common. The first 
 and most used is that snown by Fig. (55), a, where the fan 
 Is in the basement of the building and forces the air by 
 pressure upward through the ducts and into the rooms. 
 This causes the air within the entire building to be at a 
 
 ! / 
 
 Fig. 
 
 Diagram of Plenum 
 System. 
 
 b. 
 
 Diagram of Exhaust 
 System. 
 
 pressure very slightly higher than the atmosphere, and 
 hence all leakages will be outward through doors and win- 
 dow crevices. A system so instaPed is usually called a 
 plenum system. The fan may, however, be of the exhausting 
 type, Fig. (55), b, and placed in the attic with which ducts 
 from the rooms connect, so that the fan tends to keep the 
 air of the building at a slight vacuum as compared with 
 the atmosphere, thus inducing ventilation. Air is then 
 
PLENUM WARM ATR HEATING 
 
 119 
 
 supposed to enter the basement inlet, pass over the coil 
 surface, and, when heated, pass to the various rooms 
 through the ducts provided. But air from the atmosphere 
 will just as readily leak in at windows or other crevices, 
 as to come in over the heaters, and then the system will 
 fail in its heating work. B or this reason the exhaust heating 
 system, as it is usually known, is seldom installed, except 
 where aid in the prompt removal of malodors is desired. 
 Combined plenum and exhaust systems are to be recom- 
 mended wherever the expense can be justified. 
 
 93. Blowers and Fans: Many methods of moving air 
 for ventilating and heating purposes have been devised, 
 some positive at all times, others so dependent upon the ex- 
 istence of certain conditions as to be a constant source of 
 trouble. It is coming to be a very generally accepted fact, 
 that if air is to be delivered at definite times, in definite 
 quantities and in definite places, it must be force^. there, and 
 not merely allowed to go under conditions readily changing 
 or disappearing. The recognition of this fact has led to a 
 very common use of the mechanical fan or blower for im- 
 pelling air, and this use has, in turn, caused the develop- 
 ment of fans and blowers to a fairly high degree of 
 efficiency. 
 
120 
 
 HEATING AND VENTILATION 
 
 By the aid of the mechanical apparatus, air may be 
 moved positively in either of two ways, by the exhaust method 
 and by the plenum method, each having developed fans best 
 suited to its needs. In the exhaust method the fan is corn- 
 
 Fig. 57. 
 
 monly of the disk or propellor blade type, shown in Fig. 56 or 
 57, is usually installed in the attic or near the top of the 
 building, although with a system of return ducts it may 
 be installed in the basement, and moves the air by suction. 
 Tue plenum system uses a fan of the paddle wheel type, 
 shown in Bigs. 58 and 59; the first is the standard form 
 of fan wheel in common use, and the second is a more 
 recent development of the same, called the "turbine" fan 
 wheel, shown direct connected to a De Laval steam turbine. 
 Tne wheels of the fans are also shown. Tests of the latter 
 wheel seem to show a somewhat higher efficiency than has 
 heretofore been possible with the older forms. Both of 
 these forms of fans are used in plenum work, and are 
 placed on the forcing side of the circulating system just 
 between the air Intake and the heater coils, or just follow- 
 ing the heater coils, and hence produce a pressure within 
 the building or suite heated, so that leakages are outward 
 and not so detrimental to the good working of the plant 
 as in the exhaust system. 
 
PLENUM WARM AIR HEATING 
 
 121 
 
 The motive power for fans may be of four kinds, 
 electric direct drive, steam engine or steam turbine direct 
 drive, and belt and pulley drive, as shown in Figs. 57, 58, 59 
 
 Fig". 58. 
 
 Fig. 59. 
 
 and 60. Which of these drives will be the most appropriate 
 will depend entirely upon local conditions and the nature 
 of the available power supply. The steam engine or steam 
 turbine drive is perhaps the most common, since some 
 steam must be present for the supply of the heating coils, 
 and since, too, the exhaust of the engine or turbine may 
 be used to supplement the live steam used for heating. 
 See Art. 114. 
 
 Pan housings are made in many different styles, and of 
 various materials, the more readily to fit any given set of 
 conditions. Materials employed may be of brick, wood, sheet 
 steel or combinations of these. Steel housings are the most 
 common and are made in such a variety of patterns as 
 will fit any requirement of plenum duct direction. What 
 are known as full housings are those where the entire fan 
 wheel is encased with steel and the entire unit is self-con- 
 
122 HEATING AND VENTILATION 
 
 tained and above the floor line. Three-quarter housings are 
 those where only the upper three-fourths of the fan wheel 
 is encased, the completion of the air-sweep around the 
 paddles being obtained by properly forming the brick foun- 
 dation upon which the fan is installed. The larger fans 
 are commonly three-quarter housed, especially if they are 
 to deliver air directly into underground ducts. Fig. 58 
 shows a full housing and Fig. 60 a three-quarter housing. 
 The circular opening in the housing around the shaft 
 of the wheel is the inlet of the fan, the air being thrown 
 by centrifugal force to the periphery and at the same 
 time given a circular motion, thus leaving the fan tan- 
 gentially through the discharge opening. This discharge 
 may be had delivering at any angle around the wheel, and 
 fans may be had with two or more discharge openings, usu- 
 
PLENUM WARM AIR HEATING 
 
 123 
 
 ally referred to as "multiple discharge fans," as shown in 
 Fig. 61. 
 
 Fig. 61. 
 
 94. Fresh Air Entrance to Building: and to Rooms: 
 
 The air may enter through the building wall at the ground 
 level or it may be taken from a stack built for the pur- 
 pose, providing a down draft with entrance for the air 
 at the top. This may be done in case rio washing or clean- 
 ing systems are applied and in case the air carries a great 
 deal of dust or dirt in from the street or from other 
 similar places. Usually in isolated plants or in small cities, 
 the air is taken in near the ground level from some area- 
 way that is fairly free from dust. In the larger cities, 
 however, either a washing system is installed to cleanse 
 the air before it is sent around to the rooms, or the air 
 is taken from an elevation somewhat above the ground 
 as spoken of before. The velocity of the air should be from 
 700 to 1000 feet per minute at this point and where grill 
 work or shutters of any sort are put in the opening, they 
 are usually so planned as not to obstruct the flow of the 
 air seriously. Usually a plain flat wire screen is placed 
 
124 
 
 HEATING AND VENTILATION 
 
 in the opening to keep out leaves, and doors are swung 
 from the inside in such a way as to be thrown open, leaving 
 practically the full value of the opening as a net area. 
 
 Air entrance to rooms is accomplished through reg- 
 isters or gratings which cover the ends of rectangular ducts 
 or conduits called stacks, built into the brick walls and open- 
 ing Into the respective rooms much as shown in section by 
 Fig. 20. Register sizes considered standard are given in 
 Table 14, Appendix. The velocity of the air at a plenum 
 register may be somewhat higher than with a simple fur- 
 nace, installation. With the plenum system the heat reg- 
 isters are usually placed well above the heads of the occu- 
 pants, near the ceiling, and the vent registers usually near 
 the floor. Velocities allowable at registers and up stacks 
 are shown in Table XIII, page 136. 
 
 95. Plenum Heating: Surfaces: Heating surfaces as 
 used to-day in connection with plenum systems may be 
 divided into two classes: coil surface, made of loops of 1 or 
 1% inch wrought iron pipe and cast surface, made of hollow 
 rectangular castings provided with numerous staggered pro- 
 jections to increase the outside surface and provide greater 
 air contact. To make a neater of either kind of surface, 
 successive units are placed side by side, until the requisite 
 'total area and depth has been obtained. See Arts. 110 
 and 111. 
 
 Coil surface is of 
 three kinds, that hav- 
 ing the pipes inserted 
 vertically into a hori- 
 zontal cast iron header 
 which forms the base of 
 the section, Fig. 62, that 
 having the pipes hori- 
 zontally between two 
 vertical side headers, 
 Fig. 63, and that having 
 one header vertical and 
 one header horizontal 
 called the mitre coil, Fig. 
 64. The first and last 
 forms shown are made 
 Fig. 62. with two, three or four 
 
PLENUM WARM AIR HEATING 
 
 125 
 
 pipes in depth. The standard number of pipes in any one 
 section is four. Sometimes these pipes are spaced in straight 
 lines parallel with the wind and sometimes are staggered. 
 Staggered spacing no doubt makes each pipe slightly more ef- 
 ficient but it adds friction to the fan. Efficiency tests of both 
 spacings. however, show little difference in these methods. 
 The horizontal sections and the mitre sections present this ad- 
 vantage over the vertical pipe sections, that the steam and 
 condensation is always flowing in the same direction and 
 
 JHg. 63. 
 
 =) 
 
 drainage is very simple. With 
 the vertical pipe section, 
 steam in one half of the pipes 
 must pass upward against the 
 di ection of the flow of con- 
 densation or it must carry the 
 condensation with it. That 
 half of the header supplying 
 pipes which carry steam up- 
 ward is usually drained for 
 condensation by a small hole 
 directly* into the return with 
 the result that steam often 
 blows through the header 
 
 Fig. 64. 
 
126 
 
 HEATING AND VENTILATION 
 
 without traversing the pipe 
 circuits. The third, or mitre 
 section, in addition to per- 
 fect drainage, has perfect ex- 
 pansion; the vertical header 
 serving as a steam supply, 
 and the horizontal header as 
 a drain, permit every pipe 
 to assume any position nec- 
 essary to account for a rea- 
 sonable change of length. 
 
 Cast iron radiating surface 
 for plenum systems is shown 
 in Fig. 65. It is composed, 
 primarily, of sections not un- 
 like the sections of an ordi- 
 nary direct radiator in the 
 way in which they are joined 
 together at the top and bot- 
 tom by nipples, thus forming 
 what is termed a stack. Stacks 
 are again assembled, one in 
 front of another, with respect 
 to the direction in which the 
 air passes through them, the 
 completed heater being then 
 more or less cubical in pro- 
 portion. The figure shows a ^_ Condensation' 
 heater two sections in depth Fig. 65. 
 and ten sections in width. Provided the conditions demand 
 it, the heater may be built two or even three stacks in 
 height, thus doubling or tripling the gross wind area. See 
 Art. 111. 
 
 Sections are usually made in but one thickness, 9 inches, 
 and in three heights, 40 inches, 50 inches and 60 inches, pre- 
 senting respectively, 11.5, 14 and 17 square feet of surface. 
 It is unusual to assemble less than five or more than twenty- 
 five sections to the stack. By the proper adjustment of num- 
 ber of sections to the stack, and of stacks to the heater, 
 any requirement of hot blast work may be met. 
 
PLENUM WARM AIR HEATING 
 
 127 
 
 ELEVATION. 
 
 Fig. 66. Fan Room Layout with Single Ducts along 
 Basement Ceiling and all Mixing Dampers at Plenum 
 Chamber. 
 
12S 
 
 HEATING AND VENTILATION 
 
 Pig. 67. E an Room Layout with Double Underground 
 Ducts and Mixing Dampers at Base of Room Stacks. 
 
PLENUM WARM AIR HEATING 129 
 
 No matter what kind or type of heater may be selected, 
 certain methods of installing- them have become common. 
 They may be placed on either the suction or the force side 
 of the fan, usually the former in drying- or evaporating- 
 plants, but more often the latter in heating- plants. Because 
 of their weight, ample and firm foundations must be pro- 
 vided. In most installations for heating- purposes, where 
 both tempered and heated air is supplied, the heater should 
 be raised on its foundation 18 to 24 inches to allow a 
 damper and passage way for tempered air. 
 
 96. Division of Coil Surface: It is considered best 
 practice to install a hot blast heater in two parts, known 
 as the tempering coil and the heating coil. In the calculations. 
 Arts. 107-111, the total heating surf ace- $s first obtained and 
 then this is split up into whatever arrangement is desired. 
 The tempering coils should be placed in the air passageway, 
 just within the intake for the building, and should contain 
 from one-fourth to one-third of the total heating- surface. 
 In this way the air is tempered before it reaches any other 
 apparatus, thus protecting from accumulation of frost on fan 
 and bearings and aiding in the process of lubrication. The 
 .main heat coil is placed just beyond the fan on its force 
 side. Exhaust steam from the engine is most commonly 
 used in the tempering coil only, and live steam of properly 
 reduced pressure in the main heater. This may be varied 
 by conditions, however, and all surface supplied by exhaust 
 steam if it is thought advisable. 
 
 97. Single Duct Plenum System: Duct systems in hot 
 blast work may be either of the single duct type or the 
 double duct type. In the single duct plant, every horizontal 
 duct is carried independently from the base of the room to 
 be heated to the small room called the plenum chamber, which 
 receives the hot blast from the heater. This chamber is 
 divided into an upper and a lower part, the upper receiving 
 the heated air that has been forced through the heater, 
 while the lower part receives only air that has been through 
 the tempering coils. The leader duct, from the base of 
 each vertical room-duct, is led directly opposite the parti- 
 tion between these two chambers, and a damper, regulated 
 by some system of automatic control from the rooms to be 
 heated, governs whether cool air from the lower chamber, 
 or hot air from the upper chamber, or a mixture of both, 
 
130 
 
 HEATING AND VENTILATION 
 
 shall be sent to the rooms. It can be readily seen that this 
 system produces rather a complicated net work of dampers 
 and ducts at the plenum chamber and this disadvantage has 
 limited its use very much. 
 
 98. Double Duct Plenum Systems: As its name indi- 
 cates, this system runs a double leader duct from the 
 plenum chamber to the base of each vertical room-duct, 
 the upper one of these ducts being in direct communication 
 with the upper part of the .plenum chamber and carries 
 
 hot air, while the lower 
 one is in communication 
 with the lower part of 
 the plenum chamber and 
 carries cool air. No mix- 
 ing- or throttling is done 
 except at the base of the 
 vertical room-duct, where 
 the mixing damper is lo- 
 cated, it being controlled 
 by hand or by automatics 
 directly from the room 
 above. With this scheme 
 it is evident that the 
 leader ducts for each 
 room need not be run 
 singly, but all the ducts 
 having the same general 
 direction combined in 
 one large double trunk, 
 from which branches are 
 taken to the various 
 room-ducts as required. 
 
 Fig. 68. The difference between 
 
 the two systems is shown by the two sketches, Figs. 
 66 and 67. 
 
 A hot blast plant may be installed as a basement or as 
 a sub-basement system. If the former, the leaders will be 
 suspended from the basement ceiling and constructed, usu- 
 ally, of sheet metal, thus forming what is often called a 
 "false ceiling." If the latter, they will be just below the 
 floor of the basement and will be constructed of brick and 
 mortar, or of concrete, about four inches thick. For designs 
 
PLENUM WARM AIR HEATING 
 
 131 
 
 of conduits, ducts and dampers, see Figs. 60, 66, 67 and 
 68, the last showing a simple and direct installation often 
 applied to factories of several stories. Fig. 69 shows a 
 complete steel housed plenum unit of fan, coils, dampers, 
 and duct connections. 
 
 Fig. 69. 
 
 99. Air Washing and Humidifying Systems: In con- 
 nection with mechanical warm air heating and ventilating 
 systems, there is often installed apparatus for washing 
 and humidifying the air. In crowded city districts where 
 the air is laden with dust, soot, th.e products of combus- 
 tion and other harmful gases, its purification and moisten- 
 ing becomes a most important problem. The plenum system 
 of heating and ventilating lends itself most readily to 
 the solution of this problem, with the result that modern 
 practice is tending more each day toward the combined 
 installation of ventilating and humidifying apparatus. Fig. 
 70 shows a plenum system augmented by an air washing, 
 purifying and humidifying apparatus. 
 
 A purifier usually contemplates the installation of two 
 parts, a washer and an eliminator. The washer consists essen- 
 tially of an air duct, usually located immediately behind 
 the tempering coils, and provided with streams or sprays of 
 water through which the air must pass. Numerous schemes 
 for breaking up the water in the finest sprays are on the 
 market, and their relative merits may be judged from trade 
 literature. Having caught the dust particles and dissolved 
 the soluble gases from the air, the water falls to a collecting 
 pan at the bottom of the spray chamber, and from there 
 is again pumped through the spraying nozzles. As the 
 water becomes too dirty or too warm, a fresh supply is 
 
132 HEATING AND VENTILATION 
 
 delivered to the collecting- pan. A small independent cen- 
 trifugal pump is commonly used for the circulation of 
 the spray water. 
 
 Fig. 70. 
 
 After passing through the washer, the air next encoun- 
 ters the eliminator, the purpose of which is to remove or 
 eliminate the surplus moisture and water particles remain- 
 ing suspended in the air. This is accomplished by an 
 arrangement of more or less complicated baffle plates, which 
 cause the air to change its direction suddenly many times 
 in succession, with the effect that the water particles im- 
 pinge upon and adhere to, the baffle plates. These are suit- 
 ably drained to the collecting- pan beneath the washer. 
 As the air leaves the eliminator and enters the fan it may 
 be relieved, with good apparatus, of 98 per cent, of all dust 
 and dirt, may be supplied with moisture to very near the 
 saturation point, and, in summer time under favorable con- 
 ditions, may be cooled from 5 to 10 degrees lower than the 
 atmosphere. This is due to the cooling effect of vaporizing 
 part of the water. 
 
 Special air cooling plants have been installed in connec- 
 tion with the plenum system of ventilation, whereby refrig- 
 erated brine could be circulated in the regular heating coils. 
 The description of such a plant with data, may be found in 
 the transactions of the A. S. H. & V. E. for the year 1908. 
 
CHAPTER X. 
 
 MECHANICAL, WARM AIR HEATING AND 
 VENTILATING SYSTEM. 
 
 AIR, HEATING SURFACE AND STEAM REQUIREMENT. 
 PRINCIPLES OF THE DESIGN. 
 
 100. Definitions of Terms: In the work under this gen- 
 eral heading, some of the technical abbreviations that are 
 frequently used are the following: H = B. t. u. heat loss 
 per hour by the formula, Hv = B. t. u. heat loss per hour by 
 ventilation, H' = total B. t. u. loss including ventilation 
 loss, Q = cubic feet of air used per hour as a heat carrier, 
 Q f = cubic feet of air used including extra air for ventila- 
 tion, R = total square feet of heating surface in indirect 
 heaters, ts = temperature of the steam or water in the 
 heaters, t = highest temperature of the air at the register 
 (let this be the same as the temperature of the air upon 
 leaving the heater), t' = temperature of the air in the room, 
 tv = temperature of the air at the register when extra air 
 is used for ventilation, to = temperature of the outside air, 
 K = rate of transmission of heat per square foot of surface 
 per degree difference per hour, N = the number of persons 
 to be provided with ventilation, V = velocity in feet per 
 minute and v = velocity in feet per second. Other abbre- 
 viations are explained in the text. 
 
 101. Theoretical Considerations: For illustrative pur- 
 poses, references will frequently be made throughout this 
 discussion to a sample plenum design, Figs. 74, 75 and 76. 
 These show the essential points of most plenum work and 
 will serve as a basis for the applications. In working up 
 any complete design the following points should be theo- 
 retically considered for each room: the heat loss, the cubic 
 feet of air per hour needed as a heat carrier (this should 
 be checked for ventilation), .the net area of the register 
 in square inches, the catalog size of the register, and the 
 area and size of the ducts. In addition to these the follow- 
 ing should be investigated for the entire plant: the size 
 of the main leader at the plenum chamber, the size of the 
 principal leader branches, the square feet of heating sur- 
 face in the coils, the lineal feet of coils, the arrangements 
 of the coils in groups and sections, the horse power and 
 
134 HEATING AND VENTILATION 
 
 the revolutions per minute of the fan including the sizes 
 of the inlet and the outlet of the fan, the horse power 
 of the engine including the diameter and the length of 
 stroke, and the pounds of steam condensed per hour in the 
 coils. 
 
 Fresh air is taken into the building at the assumed 
 lowest temperature, to degrees, is carried over heated coils 
 and raised to t degrees, is propelled by fans through ducts 
 to the rooms and then exhausted through vent ducts to 
 the outside air, thus completing the cycle. It will be the 
 object to so discuss this cycle that it will be general and 
 so it will apply to any case which may be brought up. 
 
 102. Heat Loss and Cubic Feet of Air Exhausted per 
 Hour: It is assumed here, that in all mechanical draft 
 heating and ventilating systems, tlie circulating air is all taken 
 from tlie outside and thrown away after being used. Some installa- 
 tions have arrangements for returning the room air to the 
 coils, for reheating, but such schemes should be considered 
 as features added to the regular design rather than as 
 being a necessary part of it. It is best to design the plant 
 with the understanding that all the air is to be thrown 
 away, then it will be large enough for any service that it 
 is expected to handle. Having found H by some acceptable 
 formula, the total heat loss is (compare with Arts. 29 and 
 36.) 
 
 (Q or Q') (f to) 
 
 H' = H -\ (40) 
 
 55 
 
 When *' = 70 and to = zero, this formula reduces to 
 H' = H + 1.27 (Q or Q') 
 
 To determine whether Qo or Q f will be used find how many 
 people would be provided with ventilating air with the 
 volume Q. If Q = 55 H -j- (t *'), * = 140 and f = 70, then 
 
 55 H H H 
 
 N = = = approximately (41) 
 
 1800 (t O 2290 2300 
 
 If more people than N will be using the room at any one 
 time, then Q' will be used instead and this value would be 
 1800 times the number of persons in the room. In any 
 ordinary case, Q will be sufficient. When this is so, formula 
 (40) reduces to 
 
 H' = 2 H (42) 
 
PLENUM WARM AIR HEATING 135 
 
 The reasoning- of this formula is easily seen when it is re- 
 membered that the heat given off from the air in dropping 
 from the register temperature, 140, to the room tempera- 
 ture, 70% goes to the radiation and leakage losses, H, while 
 that given off from the inside temperature, 70, to that of 
 the outside temperature, 0, is charged up to ventilation 
 losses, Hv. Since, then, these values are equal, H' = H -j- H 
 = 2 H. 
 
 APPLICATION. Referring to Fig. 75, room 15, and Table 
 XXVI, page 140, it is seen that the calculated heat loss H, for 
 this room, with f = 70 and to = 0, is 70224 B. t. u. per hour; 
 also, that the cubic feet of air, Q, if t = 140, is 54775 per 
 hour. Applying formula (42), the total heat loss, H', be- 
 comes 140448 B. t. u. per hour, or twice the amount found 
 by the heat loss formula. With 54775 cubic feet of air sent 
 to the room per hour, this will provide good ventilation for 
 thirty persons. Suppose, however, that fifty persons were 
 to be provided for; this would require 50 X 1800 90000 
 cubic feet of air per hour. With this increased number of 
 people in the room, the total heat loss would not be as 
 stated above, but would be according to formula (40) 
 
 90000- (70 0) 
 
 B' = 70224 H 184864. 
 
 55 
 
 103. Temperature of the Entering Air at the Register: 
 
 In plenum work, the registers are placed higher in the 
 wall and the velocity of the air is usually carried a little 
 higher than in furnace work. It may be said that 140 is 
 probably the accepted temperature for design, excepting 
 where an extra amount of air is demanded for ventilation 
 purposes. In the latter case, the temperature of the air 
 would necessarily drop below 140 in order that the room 
 would not be overheated. The general formula is 
 
 55 H 
 tv = t' + (43) 
 
 APPLICATION. Referring to room 15 and (compare with 
 Art. 38) assuming the heat loss to have been figured as 
 before with ventilating air supplied sufficient for 50 per- 
 sons, 90000 cubic feet per hour, then the temperature of 
 the air at the register is 
 
 55 H 
 
 t = 70 H = 103%* 
 
 90000 
 
136 
 
 HEATING AND VENTILATION 
 
 The temperature of the air at the register is the 
 same or slightly less than the temperature of the air upon 
 leaving the coils. If this room were to be the only one 
 heated, then the coils would be figured for a final temper- 
 ature of the air at 104, but other rooms may have air 
 entering at higher temperatures, hence the temperature t 
 upon leaving the coils should be that of the highest t at 
 the registers. 
 
 104. Cubic Feet of Air needed per Hour: The following 
 amount of air will be needed per hour as a heat carrier 
 (compare with Art. 36). 
 
 55 H H 
 
 Q = ; where t = 140 and V 70, Q 
 
 * t' 1.27 
 
 If extra air be needed for ventilation, Q' = 1800 N. 
 
 105. Air Velocities, V, in the Plenum System: Table 
 XIII gives the velocities in feet per minute that have been 
 found to give good satisfaction in connection with blower 
 systems. 
 
 TABLE XIII. 
 Air Velocities in the Plenum System. 
 
 
 Fresh 
 Aii- 
 Intake 
 
 Over 
 Coils 
 
 Main 
 Duct 
 Near 
 Fan 
 
 Smaller 
 Branch 
 Ducts 
 
 Stacks 
 
 Registrs 
 or other 
 Open'gs 
 
 Offices, 
 Schools, etc. 
 
 s ? 
 
 S> 
 
 800 to 1200 F. P. M. 
 Average KXK) F. P. M. 
 
 1200 to 
 1800 
 say 1500 
 
 800 to 
 1200 
 say 900 
 
 500 to 
 700 
 say 600 
 
 300 to 
 400 
 say 300 
 
 Auditoriums, 
 Ohurches.etc. 
 
 1500 to 
 2000 
 say 1800 
 
 1000 to 
 1500 
 say 1200 
 
 600 to 
 800 
 say 700 
 
 400 to 
 600 
 say 400 
 
 Shops and 
 Factories. 
 
 1500 to 
 3000 
 say 2000 
 
 1000 to 
 2000 
 say 1500 
 
 600 to 
 1000 
 say 800 
 
 400 to 
 
 800 
 say 500 
 
 106. Cross Sectional Area of Registers, Ducts, etc: 
 
 With the above velocities in feet per minute, the square 
 inches of net opening at any part of the circulating sys- 
 tem can be obtained by direct substitution in the general 
 formula. 
 
 144 (0 or Q') 
 
 A = (Q or Q') X = 2.4 (44) 
 
 60 V V 
 
PLENUM WARM AIR HEATING 137 
 
 The calculated duct sizes, of course, refer to the warm 
 air duct. The cold air duct in double duct systems need not 
 be so large because on warm days, when only tempered air 
 is needed, the steam may be turned off from one or more 
 of the heaters and the warm air duct can then be used to 
 furnish what otherwise would be required from the cold 
 air duct. On account of this flexibility, it seems only nec- 
 essary to make the cold air duct about one-half the cross 
 sectional area of the warm air duct. For convenience of 
 installation, therefore, it would be well to make the form- 
 er of equal width to the latter and one-half as deep, unless 
 by so doing the cold air duct becomes too shallow. 
 
 APPLICATION. Assuming 2000000 cubic feet of air to pass 
 through the main heat duct, 5 ig. 74, per hour at the velocity 
 of 1800 feet per minute, the duct will be approximately 20 
 square feet in cross section, or 2y 2 by 8 feet. The two main 
 branches at B, will carry about 800000 cubic feet per hour 
 each at the same velocity and will be 7.4 square feet in 
 area or, say, 2 by 4 feet. The same branches at C, will 
 carry about 400000 cubic feet per hour each at a velocity of 
 1500 feet per minute and will be 4.4 square feet in area or, 
 say, 2 by 2% feet and the branch D, will carry about 300000 
 cubic feet at a velocity of 1200 feet per minute and will be, 
 say, 1^2 by 2% feet. 
 
 The stack sizes were first figured for the velocity of 600 
 feet per minute. These sizes were then made to fit the lay- 
 ing of the brick work such that the velocities would be 
 anywhere between 300 to 600 feet per minute. The net 
 register was figured for an air velocity of 300 feet per 
 minute and the gross registers were assumed to be 1.6 
 times the net area. See Art. 126. 
 
 107. Square Feet of Heating: Surface, R, in the Coils: 
 
 To determine theoretically the number of square feet of 
 heating surface in the coils of an indirect heater, the fol- 
 lowing formula may be used, 
 
 H' 
 R = (45) 
 
 E ( t ...l^l 
 
 \ 2 
 
 Since the coils are figured from the entire building loss, 
 H r will include the sum of all the heat losses of the various 
 rooms. The chief concern in the use of this formula, as 
 
138 HEATING AND VENTILATION 
 
 stated, is to determine the best value for K, the rate of 
 transmission. Prof. Carpenter in H. and V. B., Art. 52, 
 quotes extensively from experiments with coils in blower 
 systems of heating and summarizes all in the formula, K = 
 2 + 1.3 V^T where v = average velocity of air over the coils 
 in feet per second. With the four velocities most appli- 
 cable to this part of the work, i. e., 800, 1000, 1200 and 1500 
 feet per minute, this becomes 
 
 800 feet per minute K = 6.9 
 
 1000 feet per minute K 7.3 
 
 1200 feet per minute K 7.8 
 
 1500 feet per minute K 8.5 
 
 In the table of probable efficiencies of indirect radiators in 
 Art. 54 by the same author, the values are somewhat high- 
 er, being, 
 
 750 feet per minute K = 7.1 
 
 1050 feet per minute K = 8.35 
 
 1200 feet per minute K = 9. 
 
 1500 feet per minute K = 10. 
 
 The values of K, as given here, are certainly very safe 
 when compared to quotations from other experimenters, 
 some of them exceeding these values by 50 per cent. It 
 is always well to remember that a coil that has been in 
 service for some time is less efficient than a new coil, be- 
 cause of the dirt and oil deposits upon the surface, hence 
 it is best in designing, not to take extreme values for ef- 
 ficiency. Assuming K = 8.5 and 1000 feet per minute air 
 velocity, which are probably the best values to use in the 
 calculations, also t = 227 (5 pounds gage pressure), t 
 140 and to = 0, formula 45 becomes 
 
 E r H' H' 
 
 R = say (46) 
 
 / 140 + 0\ 1335 1400 
 
 8.5/227 } 
 
 Table XIV quoted by Mr. C. L. Hubbard in Power Heat- 
 ing & Ventilation, Part III, page 557, gives the efficiencies 
 of forced blast pipe heaters and the temperatures of air 
 delivered. 
 
PLENUM WARM AIR HEATING 
 
 139 
 
 TABLE XIV. 
 
 Efficiencies of Forced-Blast Pipe Heaters, and Temperatures 
 
 of Air Delivered. 
 Velocity of air over coils at 800 feet per minute. 
 
 Rows 
 of Pipe 
 Deep 
 
 Tetnp. to which the air 
 will be raised from zero 
 
 Efficiency of the heating sur- 
 face in B.t.u.per sq.ft. perhr 
 
 Steam pressure in heater 
 
 Steam pressure in heater 
 
 5 Ib. 
 
 20 Ib. 
 
 60 Ib. 
 
 5 Ib. 
 
 20 Ib. 
 
 60 Ib. 
 
 4 
 
 30 
 
 35 
 
 45 
 
 1600 
 
 1800 
 
 2000 
 
 6 
 
 50 
 
 55 
 
 65 
 
 1600 
 
 1800 
 
 2000 
 
 8 
 
 65 
 
 70 
 
 85 
 
 1500 
 
 1650 
 
 1850 
 
 10 
 
 80 
 
 90 
 
 105 
 
 1500 
 
 1650 
 
 1850 
 
 12 
 
 95 
 
 105 
 
 125 
 
 1500 
 
 1650 
 
 1850 
 
 14 
 
 105 
 
 120 
 
 140 
 
 1400 
 
 1500 
 
 1700 
 
 16 
 
 120 
 
 130 
 
 150 
 
 1400 
 
 1500 
 
 1700 
 
 18 
 
 130 
 
 140 
 
 160 
 
 1300 
 
 1400 
 
 1600 
 
 20 
 
 140 
 
 150 
 
 170 
 
 1300 
 
 1400 
 
 1600 
 
 For a velocity of 1000 feet per minute multiply the 
 temperatures given in the table by 0.9 and the efficiencies 
 by 1.1. 
 
 Mr. F. R. Still of the American Blower Co., Detroit, 
 gives the following formula for the total B. t. u. trans- 
 mitted per square foot of surface per hour between the 
 temperature of the steam and that of the entering air. 
 
 Total B. t. u. transmitted = c ^v^ts fo) (47) 
 
 in which case v is the velocity in feet per second and c is 
 a constant as follows: 
 
140 
 
 HEATING AND VENTILATION 
 
 TABLE XV. 
 Values of c. 
 
 
 Safe Factor 
 
 Max. Factor 
 
 1 section 4 rows of pipe 
 
 8.45 
 
 4.4 
 
 2 sections 8 rows of pipe 
 
 3. 
 
 8-4 
 
 3 sections 12 rows of pipe 
 
 2-63 
 
 2.85 
 
 4 sections 16 rows of pipe 
 
 2.88 
 
 2.45 
 
 5 sections 20 rows of pipe 
 
 2.12 
 
 2.2 
 
 6 sections 24 rows of pipe 
 
 1.95 
 
 2.05 
 
 7 sections 28 rows of pipe 
 
 1.80 
 
 1.95 
 
 8 sections 82 rows of pipe 
 
 1.65 
 
 1.85 
 
 9 sections 86 rows of pipe 
 
 1.52 
 
 1.8 
 
 10 sections 40 rows of pipe 
 
 1-4 
 
 1.75 
 
 From the above values of c, Table XVI has been com- 
 piled, assuming * s = 227, to and c = a safe value. 
 
 TABLE XVI. 
 
 31 
 
 Total transmission in B. t. u. per sq. ft. per hour. 
 * = 227; * = 
 
 <D 
 
 |! 
 
 Bows of pipe deep. 
 
 ii 
 
 
 
 
 
 
 
 
 
 
 >s 
 
 4 
 
 8 
 
 12 
 
 16 
 
 20 
 
 24 
 
 28 
 
 82 
 
 800 
 
 2840 
 
 2470 
 
 2164 
 
 1920 
 
 1750 
 
 1606 
 
 1450 
 
 1860 
 
 1000 
 
 8200 
 
 2790 
 
 2440 
 
 2170 
 
 1900 
 
 1810 
 
 1670 
 
 1535 
 
 1200 
 
 8500 
 
 8040 
 
 2670 
 
 2860 
 
 2150 
 
 1980 
 
 1825 
 
 1678 
 
 1500 
 
 8950 
 
 8400 
 
 2981 
 
 2645 
 
 2400 
 
 2220 
 
 2020 
 
 1870 
 
 Cast iron heaters are being used for indirect heating in 
 many cases, replacing the old-fashioned pipe coil heaters. 
 The efficiency of these heaters is, according to tests, about 
 the same as that of the pipe coil heaters and hence formulas 
 45 and 46 would apply in the same way for both kinds. 
 
PLENUM WARM AIR HEATING 
 
 141 
 
 Table XVII gives values of heat transmission for various 
 sections, taken from tests upon Vento cast iron heaters set 
 up in banks, and is added as a means of comparison with 
 the values quoted on the pipe coil heaters. 
 
 TABLE XVII. 
 
 Rate of Transmission of Heat, K, through Vento Coils. 
 Steam 227, air entering at 0. 
 
 Velocities of air over coils. 
 
 Sections 
 
 800 
 
 1000 
 
 1200 
 
 1500 
 
 1 
 
 7.6 
 
 8.8 
 
 10. 
 
 11.8 
 
 2 
 
 7.1 
 
 8.2 
 
 9.2 
 
 10.5 
 
 3 
 
 6.6 
 
 7.7 
 
 8.6 
 
 9.7 
 
 4 
 
 6".l 
 
 7.1 
 
 7.9 
 
 9. 
 
 5 
 
 5.6 
 
 6.5 
 
 7-8 
 
 8-8 
 
 6 
 
 5.2 
 
 6. 
 
 6.7 
 
 7-7 
 
 7 
 
 4.8 
 
 5.5 
 
 6-2 
 
 7-1 
 
 In applying these values of K to formula 45 it should 
 
 be remembered that to would be used instead of K - 
 
 APPLICATION 1. Where Heating Only is Considered. Refer ring- 
 to Table XXV let H for the entire building be 1483251. 
 Then from Art. 104, Q = 1156935, by formula 42, H f = 2966502 
 and by formula 46, the coil surface is 
 
 2966502 
 
 = 2222 square feet. 
 
 R = 
 
 8.5 
 
 ^227 - 
 
 140 + 
 
 \ 
 
 With three lineal feet of 1 inch pipe per square foot of 
 surface, we have 6666 lineal feet of coils in the heater. 
 
 APPLICATION 2. Where Ventilation is Considered. Assume 1100 
 people in the building on a zero day and Q' = 2000000, then, 
 H' = 1483251 + 1.27 X 2000000 = 4023251 and 
 
 4023251 
 R = =3014 sq. feet = 9042 lineal feet. 
 
 8.5^227 - 
 
142 HEATING AND VENTILATION 
 
 This value is probably the greatest amount that would 
 be needed. In such a case, when the rooms were supplied 
 with extra air, the register temperatures over the entire 
 building- may be less than 140 degrees. Suppose in this 
 case the temperature to be, by formula 43, t = 70 4- 
 55 X 1483251 -f- 2000000 = 111, then 
 
 4023251 
 
 B = = 2760 sq. ft. = 8280 lineal ft. 
 
 Ill + 
 
 / 
 
 '('"- 
 
 In using- this formula, the value t = 140 is to be recom- 
 mended wherever part of the rooms are not provided with 
 extra amounts of ventilating air. By so doing the ducts and 
 registers may be held down to a more moderate size and 
 at the same time give a safer figure for the heating surface. 
 
 108. Approximate Rules for Plenum Heating Surfaces: 
 
 The following approximate rules are sometimes used in 
 checking up heating surface in the coils. These are not 
 recommended and should be used with caution. 
 
 Rule 1. "Allow one lineal foot of 1 inch pipe for each 
 65 to 125 cubic feet of room space"; 65 for office buildings, 
 schools, etc. and 125 for shops and laboratories. Since this 
 building has approximately 500000 cubic feet of room space, 
 it gives 7700 lineal feet of 1 inch pipe in the heater. 
 
 Rule 2. "Allow 200 lineal feet of 1 inch pipe for each 
 1000 cubic feet of air per minute at a velocity of 1500 feet 
 per minute." Applying to the above building when the air 
 moves over the coils at 1000 feet per minute, the heated 
 surface is only about four-fifths as valuable and would 
 require 250 lineal feet per each 1000 cubic feet of air per 
 minute. This gives 8333 lineal feet of coils. 
 
 109. Final Air Temperatures: Since the amount of 
 heat transmitted is directly proportional to the difference 
 of temperature between the two sides of the metal, it is 
 readily seen that the first coils in the bank are the most 
 efficient, and that this efficiency drops oft' rapidly as the 
 air becomes heated in passing over the coils. Final tem- 
 peratures, for different numbers of coil sections in banks, 
 have been found by experiment and may be taken from 
 Table XVIII. See also Table XIV, page 139. 
 
PLENUM WARM AIR HEATING 
 
 143 
 
 TABLE XVIII. 
 
 Temperatures of air upon leaving Coils, steam 227, air 
 entering- at 0. 
 
 Sections 
 
 No. of 
 Bows 
 
 Velocities of air through coils in F. P. M. 
 
 800 
 
 1000 
 
 1200 
 
 1500 
 
 1 
 
 4 
 
 42 
 
 33 
 
 28 
 
 23 
 
 2 
 
 8 
 
 71 
 
 62 
 
 56 
 
 52 
 
 3 
 
 12 
 
 96 
 
 87 
 
 80 
 
 75 
 
 4 
 
 16 
 
 119 
 
 108 
 
 101 
 
 93 
 
 5 
 
 20 
 
 136 
 
 125 
 
 116 
 
 108 
 
 6 
 
 24 
 
 153 
 
 140 
 
 131 
 
 120 
 
 7 
 
 28 
 
 169 
 
 155 
 
 143 
 
 131 
 
 8 
 
 32 
 
 183 
 
 166 
 
 154 
 
 141 
 
 These temperatures may be increased about 10 per cent, 
 for 20 pounds gage pressure. 
 
 Table XIX shows similar results quoted for the Vento 
 cast iron heaters. 
 
 TABLE XIX. 
 
 Temperatures of air upon leaving Vento Coils, steam 227, 
 air entering at 0. 
 
 Number 
 
 Velocities of air through coils in F. P. M. 
 
 01 STACKS 
 deep 
 
 800 
 
 1000 
 
 1200 
 
 1500 
 
 1 
 
 38 
 
 34 
 
 31 
 
 29 
 
 2 
 
 69 
 
 62 
 
 59 
 
 55 
 
 3 
 
 98 
 
 89 
 
 83 
 
 76 
 
 4 
 
 120 
 
 110 
 
 103 
 
 94 
 
 5 
 
 135 
 
 125 
 
 118 
 
 109 
 
 6 
 
 148 
 
 138 
 
 130 
 
 120 
 
 7 
 
 155 
 
 145 
 
 138 
 
 128 
 
144 HEATING AND VENTILATION 
 
 110. Arrangement of Coils in Pipe Heaters: Coil sec- 
 tions are arranged with 2, 3 and 4 rows of pipes per sec- 
 tion. Unless special reference is made to this point, the 
 latter value is understood. Having found the total square 
 feet of heating surface in the heater, obtain from the tem- 
 perature tables the number of sections deep the heater will 
 need to be to produce the desired temperature, and find the 
 number of square feet of heating surface per section and 
 per row of coils. Let this latter value be A. Also find the 
 net wind area across the coils, assuming, say, 1000 feet per 
 minute velocity. From the net wind area, find the gross 
 cross sectional area of the heater by the value. 
 
 Gross wind area = 2.5 times net wind area. (48) 
 
 From the gross area the size of the heater may be selected. 
 In selecting the heater, the following check should be ap- 
 plied. Find the number of square feet of heating surface, 
 B, in each row of the coils as figured from the gross area 
 and compare with A. These must be made to agree. 
 
 Let the net area between the tubes, N. A., the space 
 occupied by the tubes, T. A., and the gross cross sectional 
 wind area through the tube, Q. W. A., be respectively 
 
 Q or Q' Q or Q' Q or Q' 
 
 N. A. = ; T. A. = ; and G. W. A. = . (49) 
 
 60 V 40 V 24 7 
 
 Since the cross sectional space T. A. occupied by the tubes 
 is to the coil surface per row as 1 : 3.1416, the total coil 
 surface in one row of tubes is 
 
 3.1416 (Q or Q') (Q or Q') 
 
 B! = = .08 
 
 40 7 7 
 
 Reduced to the basis of the net area, N. A., we have 
 
 Ri = 4.8 times N. A. (50) 
 
 If B is greater than A, then the total heating surface 
 must be increased in that proportion, since the Dumber of 
 sections cannot be less or the final temperature will drop 
 below the required degree, and the net cross section cannot 
 be less or the velocity of the air will be greater than that 
 desired. On the other hand, suppose B should be less than 
 A. In that case the total heating surface will not change 
 from that calculated. Either B may remain the same as 
 calculated and the number of sections increased (if de- 
 sirable) until all the heating surface is accounted for, or A 
 may remain constant and B may be increased. The latter 
 
PLENUM WARM AIR HEATING 145 
 
 method is probably a better one since it gives larger wind 
 areas and consequently reduced velocities of the air, which 
 in many cases is desirable, and avoids placing heating sur- 
 face at the rear of the bank where it is less efficient. 
 
 Assembled sections of pipe coil heaters are supplied by 
 manufacturers from the smallest size of 3 feet x 3 feet, to 
 the largest size of 10 feet x 10 feet; these dimensions being 
 those of the gross cross-sectional area, and noi dimension*? 
 over all. Between the two limits, both height and breadth 
 usually vary by 6 inch increments. For exact sizes, consult 
 dimension tables in manufacturers' catalogs. 
 
 APPLICATION 1. In Article 107, let R = 2222, Q = 1156935, 
 V = 1000 and t = 140; then from Table XVIII the heater will 
 require 24 rows of coils in depth to give the required tem- 
 perature. Next find RI = 93 square feet of heating surface 
 per row, also 
 
 N. A. = 19.7; T. A. = 29.1; and Q. W. A. = 48.5. 
 Checking N. A. with an air velocity of 1000 feet per min- 
 ute gives 1156935 -=- (60 X 1000) =19.3 square feet, which 
 shows that the above arrangement is satisfactory. Now 
 from the value G. W. A. = 48.5 select a heater, say, 6 feet 
 x 8 feet. 
 
 APPLICATION 2. In article 107, let R = 3014, Q' = 2000000, 
 7 = 1000 and t = 140; then as before, the heater will need 
 24 rows of coils. Find in this case RI = 126 and 
 
 N. A. 26.3; T. A. = 39.4; and Q. W. A. = 65.7. 
 Checking from the volume of air delivered, obtain 
 
 N. A. = 33.3; T. A. = 50; and G. W. A. = 83.3. 
 From N. A. = 33.3 find B x = 160, which shows that it will 
 
 be necessary to increase the total heating surface to, j-^ 
 
 LZ6 
 X 3014 = 3826 square feet. If it were considered advisable 
 
 to have 1200 feet air velocity the heating surface per row 
 would be reduced to 135 and the temperature, t, would be 
 reduced to 131. Both conditions are reasonable and in 
 many cases would be considered satisfactory. 
 
 Selecting the heater for the gross area of 83.3 square 
 feet, from the catalog size, would probably give a single 
 section 9 feet x 9 feet or a double section, each part 6 
 feet x 7 feet. 
 
 111. Arrangement of Sections and Stacks in Vento Cast 
 Iron Heaters: Applying only to Case 2, Art. 107, let R = 
 
1*6 HEATING AND VENTILATION 
 
 3014, Q' = 2000000, V = 1000 N. A. (least value) = 33.3, and * = 
 140; also take for cast iron heaters 
 
 G. W. A. = 2.3 times N. A. (51) 
 
 From Table 34, Appendix, either of the following arrange- 
 ments will give the necessary N. A. First. Six stacks, 
 each 620 square feet, and built up of 20 sections 50 inches 
 high on top of 20 sections, 60 inches high, making a total 
 of 110 inches high and 100 inches long. Second. Seven stacks 
 each 612 square feet, and built up of 18 sections^ 60 inches 
 high on top of 18 sections 60 inches high, making a total 
 of 120 inches high and 90 inches long. With the above ar- 
 rangement of, say, six stacks, Table XIX gives a possible 
 temperature of 138 degrees, which is slightly below what is 
 required. It also gives a total heating surface of approxi- 
 mately 25 per cent, in excess of the requirement. With this 
 arrangement it will be necessary to increase the heating 
 surface arbitrarily or to increase the air velocity. 
 
 112. Use of Hot Water in Indirect Coils: In most cases 
 low pressure steam is used as a heating medium in the indirect 
 coils. It is possible, however, to rse hot water instead, where 
 a good supply is to be had. In such an arrangement the coils 
 will be figured from formula (45), using all values the same 
 as for steam excepting t s , which would be replaced by the 
 average temperature of the water. The piping connections 
 and the arrangements of the coils would follow the same 
 general suggestions as already stated. 
 
 113. Pounds of Steam Condensed per Square Foot of 
 Heating: Surface per Hour: From Art. 107 it is readily seen 
 that the number of pounds of condensation per hour per 
 square foot of surface in the coils is 
 
 TJt 
 
 m ~ R X Heat given off per pound of condensation. 
 
 APPLICATION. Let R = 3014 and W = 4023251; also let 
 one pound of dry steam at five pounds gage in condensing 
 to water at 212 degrees give off 1155.6 180.9 = 974.7, say, 
 975 B. t. u. (see Tables 2 and 6, Appendix.), then 
 
 4023251 
 
 m = = 1.37 pounds. 
 
 3014 X 975 
 
 This amount should, of course, be considered an average. 
 The first and last section in any bank would vary above 
 
PLENUM WARM AIR HEATING 147 
 
 and below this amount by as much as 50 per cent, in the 
 average plant. The first coils should condense as much as 2 
 pounds of steam per square foot of surface per hour. 
 
 114. Pounds of Dry Steam Needed in Excess of the 
 Exhaust Steam Given off Prom the Engine: Let the heat- 
 ing value of the exhaust steam from the engine be, say, 85 
 per cent, of that of good dry steam, also let the engine 
 use 40 pounds of dry steam per horse power hour in driv- 
 ing the fan. From Art. 124, the engine will use 40 X 13.6 
 = 544 pounds of steam per hour and the heating value will 
 be, 975 X .85 = 828 B. t. u. per pound or 828 X 544 = 450432 B. 
 t. u. total per hour. Then 4023251 450432 = 3572819 B. 
 t. u., and 3572819 975 3664 pounds of steam. The boiler 
 will then supply to the engine and coils, 3664 + 544 = 4208 
 pounds of steam total and will represent, approximately, 
 4208 -r- 30 = 140 boiler horse power. 
 
CHAPTER XL 
 
 MECHANICAL, WARM AIR HEATING AND 
 VENTILATING SYSTEM. 
 
 PRINCIPLES OF THE DESIGN, CONTINUED. 
 FANS AND FAN DRIVES. 
 
 115. Theoretical Air Velocity: The theoretical velocity 
 of air v, flowing from any pressure, pa, to any pressure, pb, 
 is obtained from the general equation v = ^2gh, where v 
 is given in feet per second, g 32.16 and Ji head in feet 
 producing flow. This latter value may be easily changed 
 from feet of head to pounds pressure and vice-versa. 
 
 When exhausting air from any enclosed space into 
 another space containing air at a different density, the 
 force which causes movement of the air is pa p& say, 
 PX. These recorded pressures may be taken by any stand- 
 ard type of pressure gage and show pressures above the 
 atmosphere. When exhausting into the atmosphere, the 
 value pb is zero and pa = p x . The fact that a difference of 
 pressure exists between two points indicates that there are 
 either two actual columns (or equivalent as in Fig. 8) of 
 air of different densities connected and producing motion, 
 or that, by mechanical means, a pressure difference is crea- 
 ted which may easily be reduced to an equivalent head h, 
 in feet, by dividing the pressure head by the density of the 
 air, as 
 
 pressure difference pa pi> 
 
 density d 
 
 Let pa p& = PX = ounces of pressure per square inch of 
 area producing velocity of the air; also, let g = acceleration 
 due to gravity = 32.16 and d = density, or weight, of one 
 cubic foot of dry air at 60 degrees and at atmospheric pres- 
 sure (Table 9, Appendix, then, substituting in the gen- 
 eral equation, we have 
 
 64.32 X 144p* 
 
 = 87 VP* (53) 
 
 .0764 X 16 
 
 Since the pressure producing flow is usually measured 
 in inches of water, tiw, the above can be changed to equiva- 
 lent height of air column by 
 
 weight of water, per cu. ft. at given temp. X , 
 
 weight of air at given temperature X 12 
 
 (54) 
 
PLENUM WARM AIR HEATING 149 
 
 Applying this to dry air at 60 degrees and water at the 
 same temperature (Tables 9 and 6, also Art. 15), 
 
 62.37 Tiw 
 
 h 68 h w 
 
 12 X .0764 
 then substituting in the general equation, find 
 
 v = V 64 -32 X 68 h w = 66.2 Vtiw (55) 
 
 Formula 54 at the temperatures 50, 55, 60, 65 and 70 
 
 degrees respectively, gives results varying between v = 65.5 
 
 V^ for 50 degrees and v 66.5 \T~^ for 70 degrees, which 
 leads to the approximate general rule that the theoretical 
 velocity of air, when measured by a water column gage that measures 
 in inches of water, equals sixty-six times the square root of the height 
 of the column in inches. Stated as a formula 
 
 v = 66 ^/^i^^ (56) 
 
 For calculations requiring accuracy, several factors 
 would affect the final result; these are, atmospheric pres- 
 sure, humidity, density of the air and temperature of the 
 air. Let the atmospheric pressure and the humidity be 
 constant, since these would affect the result but little, and 
 take into account, first, the density of the air. Let the 
 pressure of the atmosphere be 29.92 inches of mercury 
 (14.7 pounds = 235 ounces per square inch area) then, 
 since the density is proportional to the absolute pressure, 
 the temperature remaining constant, we have from form- 
 ula 53 
 
 64.32 X 144 px I px 
 
 = 1336 \ (57) 
 
 235 + p x 235 + 
 
 .0764 X 16 X 
 
 235 
 
 Also, from the relation existing between (53) and (55), 
 formula 57 reduces to 
 
 / h* 
 
 v = 1336 \ (58) 
 
 " 407 + h w 
 
 From formulas 57 and 58 the second columns in Tables 
 XX and XXI have been calculated. 
 
 APPLICATION. Air is exhausted from an orifice in an air 
 duct into the atmosphere. The pressure of the air within 
 the duct is one ounce by pressure gage or 1.74 inches by a 
 Pitot tube. Assuming the air to be dry and the barometer 
 standing at 29.92 inches when the water in the tube is 60 
 degrees, what is the velocity of the air? By the approxi- 
 mate formulas (53) and (56) 
 
150 
 
 HEATING AND VENTILATION 
 
 v = 87 V3~= 87 F. P. 8. 
 and v = 66 yi^'4 = 87.2 F. P. 8. 
 By formulas (57) and (58) 
 
 1 
 
 v = 1336 A/ = 86.3 F. P. 8. 
 
 * 235+1 
 
 / OT~ 
 
 and v = 1336 A/ = 87.1 F. P. 8. 
 
 * 407 + 1.74 
 
 * TABLE XX. 
 
 Column 2 figured from formula 57. 
 
 Pressure In ounces 
 per sq. Inch. 
 
 Velocity of dry air at 6QO es- 
 caping: into the atmosphere 
 through any shaped orifice in 
 any pipe or reservoir in which 
 a griven pressure is main- 
 tained. 
 
 Vol. of air in cu 
 ft. which may be 
 discharged in 1 
 min. through an 
 orifice having an 
 effective area of 
 discharge o f 1 
 sq. inch. 
 
 Ool. 3 -4- 144 
 
 H. P. required to 
 move the given 
 vol. of air under 
 the given con- 
 ditions o f dis- 
 charge. 
 
 ( Col. 3 X Col. 1 ) 
 
 Ft. per sec. 
 
 Ft. per min. 
 
 16X33000 
 
 5* 
 
 30.80 
 
 1848-00 
 
 12.83 
 
 0.00044 
 
 % 
 
 43.56 
 
 2613.60 
 
 18.15 
 
 000124 
 
 % 
 
 68.27 
 
 8196.20 
 
 22.19 
 
 0.00227 
 
 % 
 
 61-56 
 
 3693-60 
 
 25-65 
 
 0.00349 
 
 ft 
 
 68.79 
 
 4127.40 
 
 28 66 
 
 0.00489 
 
 3 /4 
 
 75-35 
 
 4521.00 
 
 31.47 
 
 0.00642 
 
 % 
 
 81.87 
 
 4882.20 
 
 83.90 
 
 0.00809 
 
 1 
 
 86.97 
 
 5218-20 
 
 36-24 
 
 0-00988 
 
 1H ' 
 
 92.18 
 
 5530.80 
 
 88.41 
 
 0.01178 
 
 IX 
 
 97.18 
 
 5830.80 
 
 40.49 
 
 0.01380 
 
 itt 
 
 101.90 
 
 6114.00 
 
 42.46 
 
 0.01592 
 
 1 1 A 
 
 106.40 
 
 6384.00 
 
 44-83 
 
 0.01814 
 
 itt 
 
 110.82 
 
 6649.20 
 
 46.11 
 
 0.02046 
 
 l 3 /4 
 
 114-86 
 
 6891.60 
 
 47.86 
 
 0.02284 
 
 1% 
 
 118.85 
 
 7131.00 
 
 49 V -52 
 
 9.02533 
 
 2 
 
 122.47 
 
 7348.20 
 
 51.03 
 
 0.02787 
 
PLENUM WARM AIR HEATING 
 
 151 
 
 TABLE XXI. 
 Column 2 figured from formula 58. 
 
 Pressure in 
 inches o f 
 
 Velocity of dry air at 60 escaping into the atmosphere 
 through any shaped orifice in any pipe or reservoir in 
 which a given pressure is maintained. 
 
 water per 
 
 
 sq. in. 
 
 
 
 
 Peet per second 
 
 Feet per minute 
 
 .1 
 
 29-04 
 
 3^56.40 
 
 .2 
 
 29.67 
 
 1780 20 
 
 .3 
 
 36.25 
 
 2175-60 
 
 .4 
 
 41.86 
 
 2511.60 
 
 .5 
 
 46.80 
 
 2708 00 
 
 .6 
 
 51.26 
 
 3075.60 
 
 .7 
 
 55 36 
 
 21.60 
 
 .8 
 
 59-10 
 
 3516-00 
 
 .9 
 
 62.60 
 
 3756.00 
 
 1. 
 
 66.14 
 
 3968.40 
 
 1.1 
 
 69-36 
 
 4161-60 
 
 1.2 
 
 72.44 
 
 4346.40 
 
 13 
 
 75-39 
 
 4523.40 
 
 1.4 
 
 78-21 
 
 4692.60 
 
 1.5 
 
 80.96 
 
 4857-60 
 
 1 6 
 
 83.59 
 
 5015.40 
 
 1.7 
 
 86-16 
 
 5169.60 
 
 1.8 
 
 88-65 
 
 5819.00 
 
 1.9 
 
 91-27 
 
 5476.20 
 
 2. 
 
 93.42 
 
 5605-20 
 
 2.1 
 
 95-72 
 
 5743-20 
 
 2 2 
 
 97 96 
 
 5877 60 
 
 2 3 
 
 100.15 
 
 6009-00 
 
 2.4 
 
 102.29 
 
 6137.40 
 
 25 
 
 104.39 
 
 6263.40 
 
 2 6 
 
 106.43 
 
 6885-80 
 
 2.7 
 
 108-46 
 
 6507 60 
 
 2.8 
 
 110.43 
 
 6<V25.80 
 
 2.9 
 
 112-37 
 
 8742.20 
 
 3. 
 
 114.28 
 
 6856-80 
 
 3 1 
 
 116.15 
 
 6969.00 
 
 32 
 
 118.00 
 
 7 s).00 
 
 3.3 
 
 119.81 
 
 7188.60 
 
 34 
 
 121.60 
 
 7296.00 
 
 3-5 
 
 123.36 
 
 7401-60 
 
 Finally, after considering the change of velocity that 
 takes place when the density changes with a constant tem- 
 perature, let the temperature change. With a constant 
 pressure, the volume changes with the absolute temperature 
 
152 
 
 HEATING AND VENTILATION 
 
 (460 + f). From this basis the values given in the second 
 columns of Tables XX and XXI, which were figured for 60 
 degrees, would be multiplied by the relative factors for 
 the given temperature as expressed in column two, Table 
 XXII, to obtain the velocity of the exhausting air at any 
 pressure and any temperature. Having found the data 
 from Column 2, find other points of information concerning 
 velocities, pressures, "weights and horse powers in moving 
 air by multiplying by the factors as given in the respective 
 columns. 
 
 TABLE XXII. 
 
 
 Factor for rel- 
 
 
 
 
 ip. in Degrees. 
 
 ative vel. at 
 same pressure 
 also relative 
 powers to 
 move same 
 vol. of air at 
 same vel. = 
 
 Factor for 
 relative pres- 
 sure, also wt. 
 of air moved 
 at same ve- 
 locity = 
 
 4600 + 600 
 
 Factor for rel- 
 ative vel. to 
 move same 
 wt. of air also 
 relative pres- 
 sure to pro- 
 duce the vel. to 
 move same wt. 
 
 Factor for rel- 
 ative power to 
 move same 
 wt. of air at 
 vel. in column 
 4 and pressure 
 in column 4 = 
 factor in col- 
 
 ti 
 
 G> 
 
 Vwt. at any T 
 
 T 
 
 of air = 
 
 umn 4 squared 
 
 t* 
 
 Wt. at 4600 + eoo 
 
 
 1 +- Col. 3. 
 
 
 30 
 
 97 
 
 1.07 
 
 .93 
 
 .87 
 
 40 
 
 98 
 
 1.04 
 
 .96 
 
 .92 
 
 50 
 
 .99 
 
 1.02 
 
 .98 
 
 .96 
 
 60 
 
 1.00 
 
 1.00 
 
 .00 
 
 1.00 
 
 70 
 
 1.01 
 
 .98 
 
 .02 
 
 1.04 
 
 80 
 
 1.02 
 
 .96 
 
 .04 
 
 1.08 
 
 90 
 
 1.03 
 
 94 
 
 -06 
 
 1.13 
 
 100 
 
 1.04 
 
 .92 
 
 .09 
 
 1.19 
 
 125 
 
 1.06 
 
 .89 
 
 .12 
 
 1.25 
 
 150 
 
 1 08 
 
 .85 
 
 .18 
 
 1.39 
 
 175 
 
 1.10 
 
 .82 
 
 .22 
 
 1.49 
 
 200 
 
 1 13 
 
 79 
 
 .27 
 
 1.61 
 
 250 
 
 1.17 
 
 .78 
 
 S7 
 
 1.88 
 
 800 
 
 1.21 
 
 .68 
 
 .47 
 
 2.16 
 
 350 
 
 1.25 
 
 .64 
 
 .56 
 
 2.43 
 
 400 
 
 1.28 
 
 .60 
 
 .67 
 
 2.79 
 
 500 
 
 1.36 
 
 .54 
 
 .85 
 
 3.42 
 
 600 
 
 1.43 
 
 .49 
 
 2.04 
 
 4.16 
 
 700 
 
 1.49 
 
 .45 
 
 2.22 
 
 4.93 
 
 800 
 
 1.56 
 
 .41 
 
 2.44 
 
 5.95 
 
 116. Actual Amount of Air Exhausted: When air of any 
 
 pressure is exhausted from one receptacle to another through 
 an orifice, the actual velocity remains about the same as 
 the theoretical velocity, being slightly reduced by friction, 
 but the volume of air discharged is greatly reduced because 
 
PLENUM WARM AIR HEATING 
 
 153 
 
 of the contraction of the stream just as it leaves the ori- 
 fice. The greatest contraction or least size of the jet is 
 located from the orifice a distance of about one-half the diam- 
 eter of the opening. A round opening is the most efficient. 
 Since the velocity is slightly reduced and the effective area 
 of the opening reduced a still greater amount, the actual 
 amount of air exhausted in any given time would be found 
 by multiplying the theoretical amount by a constant which 
 is the product of the coefficient of reduced velocity and the 
 coefficient of reduced area. From tests the following ap- 
 proximate values are quoted by the Sturtevant Company 
 in Mechanical Draft, page 152. 
 
 Orifice in a thin plate, .56 
 
 Short cylindrical pipe, .75 
 
 Rounded off conical mouth piece, .98 
 Conical pipe, angle of convergence 
 about 6, .92 
 
 117. Results of Tests to Determine the Relation be- 
 tween Pressure and Velocity: In Power, Heating and Ven- 
 tilation, page 536, Mr. Hubbard gives curves, Fig. 71, show- 
 ing the ratio of the air-velocity pressure to the peripheral- 
 velocity pressure in fan experiments; also, between the air- 
 velocity pressure and the dynamic pressure for degrees of 
 discharge opening varying from 40 per cent, to 100 per 
 cent, or full opening. 
 
 100 
 
 10 
 
 20 30 
 
 50 60 70 80 90 100 
 
 RATIO OF EFFECT. 
 
 Fig. 71. 
 
154 HEATING AND VENTILATION 
 
 In the tests a pipe, the size of the fan outlet and about 
 12 feet in length, was attached directly to the casing and 
 provided with a gate at the outer end to allow for any de- 
 gree of opening. The fan was run at constant speed and 
 the dynamic and static pressures were measured about mid- 
 way of the pipe at full opening. Then the opening was 
 changed by 10 per cent, reductions and readings taken. The 
 pressure, corresponding to the peripheral-velocity pressure, 
 was found by formula 56 and the results of the test were 
 plotted in curves showing ratios to this peripheral-velocity 
 pressure. As an illustration, the relation between the air 
 velocity pressure to the peripheral-velocity pressure for 
 full opening and discharging into free air is .43. Since 
 the velocities always vary as the square root of the pres- 
 sure (v \J2gh), we find that the velocities in this case vary 
 as V * 43 - 65 - This shows that for this one condition, the 
 air velocity at the free opening = .65 times the peripheral 
 velocity of the fan. For methods of measuring velocity 
 and pressure, see Art. 15. 
 
 118. Work Performed and Horse Power Consumed in 
 Moving Air: The foot pounds of work performed in moving 
 air equals the product of the moving force into the distance 
 moved through in any given time. Let pa pi> = PX = 
 moving force of the air in ounces per square inch and A = 
 cross-sectional area of current in square inches, then the 
 pounds per square inch will be p x -f- 16, and the foot pounds 
 of work, W, and the horse power, H. P., absorbed per min- 
 ute by the current of air in being moved, will be 
 
 60 px A v 
 
 W = = 3.75 px A v (59) 
 
 16 
 3.75 px A v 
 
 E. P. = = .000114 px A v (60) 
 
 33000 
 
 This formula may be stated in terms of the cubic feet of 
 air discharged per minute. Take the relation between PJ> 
 and ft w at 60 degrees as 12 p* = 16 X .433 h w ; also, A X v = 
 144 Q' when Q' = cubic feet of air discharged per second 
 and, from formula (58), Jiw v 2 -4- 4356, then by substituting 
 in formula 60 
 
 3.75 X .577 X v 2 X 144 Q' 
 
 H. P. = : = .0000022 v 2 Q' (61) 
 
 4356 X 33000 
 APPLICATION 1. Let the effective area of a stream of dry 
 
 air at 60 degrees, exhausting between the pressures of pa = 
 
PLENUM WARM AIR HEATING 155 
 
 \^/z ounces and po = % ounce, be 400 square inches. What is 
 the work performed per minute and the horse power con- 
 sumed? 
 
 TF = 3.75 X (1% %) X 400 X .87 = 1305 foot pounds, 
 and H. P. = .000114 X (1% %) X 400 X 87 = .1487. 
 
 APPLICATION 2. A fan is delivering 1000000 cubic feet of 
 air per hour to a heating system with a pressure of % 
 ounce. What is the theoretical horse power of the fan? 
 H. P. = .0000022 X (74. 5) 2 X 277 = 3.7 
 
 119. Actual Horse Power Consumed in Moving Air by 
 Blower Fans: The theoretical horse power of a fan is that 
 horse power necessary to move the air. This amount is al- 
 ways exceeded, however, because of the inefficiency of the 
 blower. Let E = efficiency of the blower, then formulas 60 
 and 61 become 
 
 .000114 p x A v 
 
 H. P. = (62) 
 
 E 
 .0000022 v* Q e 
 
 H. P. = (63) 
 
 E 
 
 The value E varies with the peripheral velocity and 
 the percentage of free outlet. When subjected to ordinary 
 service, the efficiency of the fan or blower may vary any- 
 where from 10 to 40 per cent. Probably a safe figure, for 
 an efficiency not definitely known, is 30 per cent, for cen- 
 trifugal fans in heating systems, (see also Art. 123.) 
 
 120. Carpenter's Practical Rules: Many experiments 
 have been run upon blower fans to determine their capacity 
 in cubic feet of air delivered per minute and to determine 
 the horse power necessary to move this air. Probably as 
 satisfactory as any are the rules quoted by Prof. Carpenter 
 in H. & V. B., Art. 162, as follows: 
 
 Rule. "The capacity of fans, expressed in cubic feet of 
 air delivered per minute, is equal to the cube of the diam- 
 eter of the fan wheel in feet multiplied by the number of 
 revolutions, multiplied by a coefficient having the follow- 
 ing approximate value: For fan with single inlet delivering 
 air without pressure, 0.6; delivering air with pressure of 
 one inch, 0.5; delivering air with pressure of one ounce, 0.4; 
 for fans with double inlets, the coefficient should be in- 
 creased about 50 per cent. For practical purposes of ven- 
 tilation, the capacity of a fan in cubic feet per revolution 
 will equal .4 the cube of the diameter in feet." 
 
 Rule. "The delivered horse power required for a given 
 
156 
 
 HEATING AND VENTILATION 
 
 fan or blower is equal to the 5th power of the diameter in 
 feet, multiplied by the cube of the number of revolutions 
 per second, divided by one million and multiplied by one of 
 the following' coefficients : For free delivery, 30; for de- 
 livery, against one ounce pressure, 20; for delivery against 
 two ounces of pressure, 10." 
 
 The two above rules stated as formulas are as follows: 
 
 where D = the diameter 
 
 for pressure of one ounce, .5 
 
 . 6 for no pressure. 
 
 Cu. ft. of air per min. 
 
 C X R. P. M. 
 in feet and C = 
 
 (64) 
 
 the, coefficient, .4 
 for pressure of one inch and 
 
 D 5 (R. P, fif.) 3 X C 
 
 H. P. = (65) 
 
 1000000 
 
 where C = 30 for open flow, 20 for one ounce and 10 for two 
 ounces pressure respectively. These two rules may be 
 checked up by sizes obtained from catalogs. They give, 
 however, in ordinary calculations, very close approxima- 
 tions. 
 
 121. If it is Desired to Obtain the Approximate Sizes of 
 the Different Parts of the Fan \Vheel and Opening, the same 
 can be found by the following table which gives good aver- 
 age values for the standard makes of fans. For more com- 
 plete data see tables in catalogs. 
 
 TABLE XXIII. 
 
 Diameter Wheel 
 Diameter Inlet, Single 
 Diameter Inlet, Double 
 Dimensions of Exhaust 
 Width of wheel at outer circumference 
 Least radial distance from wheel to 
 casing 
 Maximum radial distance from wheel 
 to casing 
 
 D 
 
 .66 D 
 .5 D 
 6 D X 
 .5 D to 
 
 .08 D to 
 .50 D to 
 
 .5 D 
 .6 D 
 
 .16D 
 1. D 
 
 to casing .50 D to 1. D 
 Least side distance from wheel to casing. 05 D to . 08D 
 
 Occupied Space 
 of 
 Full Housing Fan 
 
 
 Discharge Vert. 
 
 Discharge Horiz 
 
 Length 
 Width 
 Height 
 
 1.7 D 
 .7 D 
 1.5 D 
 
 1.5 D 
 
 .7 D 
 1.7 D 
 
PLENUM WARM AIR HEATING 157 
 
 122. Fan Drives: Fans, for heating and ventilating 
 purposes, may be driven by simple horizontal or vertical- 
 throttling or automatic steam engines, or by electric mo- 
 tors; the principal advantage of the latter being the clean- 
 liness. In either case the power may be direct- connected 
 or belt-connected to the fan. Direct-connected fans make 
 a very neat arrangement, but they require slow speed 
 engines or motors, occasionally making them so large as to 
 be prohibitive. Where engines are used, any unusual noise 
 or pounding in the parts is frequently carried through the 
 fan to the air current and up to the rooms. Belted drives 
 may run at higher speeds but they must of necessity be set 
 off from the fan ten feet or more to get good belt contact. 
 Noiseless chain drives will permit the same reductions of 
 speed and will allow the engine to be set very close to the 
 fan. Where a reduction is made in the space between the 
 engine and the fan, it had best be made in the last named 
 way. 
 
 In deciding between an engine drive and a motor drive 
 for use with steam coils, the amount of steam used in the 
 engine should not be considered a loss, since this is all 
 exhausted into the heater coils and is used instead of live 
 steam from the boilers. An engine of high efficiency is not 
 so essential either, unless the exhaust steam cannot be 
 used. Enclosed engines running in oil are preferred when 
 used on high speeds. The belt when used should, if pos- 
 sible, have the tight side below to increase the arc of 
 contact. 
 
 Electric motors have more quiet action and in special 
 cases should be specified. They would generally be speci- 
 fied for installations where the exhaust steam could not 
 be used, as in systems for ventilating only. This method of 
 driving the fan is more satisfactory in many ways but its 
 operation is usually more expensive. Direct current motors 
 are desirable, whenever they can be applied, because of the 
 convenience in obtaining changes of speed and because the 
 motors may easily be direct-connected to the fan. Alter- 
 nating current motors are used but they usually run at 
 higher speeds, requiring reduction drives and are not so 
 satisfactory in regulation. 
 
 123. Speed of the Pan: A blower fan, exhausting into 
 the open air, will deliver air with a linear velocity slightly 
 
158 
 
 HEATING AND VENTILATION 
 
 below the peripheral velocity of the fan blades, but if this 
 same fan be connected to a system of ducts and heater 
 coils, the linear velocity of the air becomes much less be- 
 cause of the increased resistance and the lag or slip that 
 takes place between the fan blades and the moving air. In 
 the average heating system this slip may be as great as 
 40 to 50 per cent. See Art. 119. It is customary, therefore, 
 in applying blowers to heating systems, to consider the 
 linear velocity of the air as it leaves the fan to be one- 
 half that of the periphery of the fan blades. Since the 
 velocity of the air upon delivery from the fan should not 
 exceed 1800 to 2500 feet per minute, the outer point on the 
 fan blades should not be expected to move faster than 3600 
 to 5000 feet per minute. Knowing this peripheral velocity, 
 the revolutions per minute may be selected and the diameter 
 obtained. 
 
 In all direct-connected fans the revolutions per minute 
 must agree with that of the engine or motor. In belted fans, 
 however, this restriction need not apply. It is found that 
 ordinary blower fans running at high speeds are very noisy 
 and so practice has determined largely the number of rev- 
 olutions to use. These may be taken as in the following 
 table. 
 
 TABLE XXIV. 
 Speeds of Blower Fans in R. P. M. 
 
 Diameter of 
 wheel 
 in inches 
 
 Differential Pressures 
 
 Va oz 
 
 y 4 oz. 
 
 loz. 
 
 IK oz. 
 
 2 oz. 
 
 18 
 
 700 
 
 900 
 
 1100 
 
 1300 
 
 1500 
 
 24 
 
 650 
 
 700 
 
 825 
 
 1000 
 
 1150 
 
 86 
 
 400 
 
 500 
 
 575 
 
 675 
 
 800 
 
 48 
 
 300 
 
 375 
 
 400 
 
 500 
 
 600 
 
 60 
 
 225 
 
 290 
 
 340 
 
 400 
 
 475 
 
 72 
 
 175 
 
 230 
 
 290 
 
 340 
 
 40C 
 
 96 
 
 150 
 
 175 
 
 200 
 
 250 
 
 300 
 
 120 
 
 125 
 
 150 
 
 175 
 
 200 
 
 225 
 
 180 
 
 75 
 
 100 
 
 110 
 
 140 
 
 160 
 
PLENUM WARM AIR HEATING 159 
 
 In some types of fans, the number of blades is in- 
 creased and the depth of the blades is diminished, making 
 the operation of the fan somewhat similar to that of the 
 steam turbine. These fans take the name of turbine fana 
 and from tests seem to show increased efficiency. As a 
 result, this type of fan for the same work may be smaller 
 for the same number of revolutions or it may be the same 
 diameter and have a reduced speed. The above table does 
 not apply to this type of fan, the speeds of which will 
 average very closely to 70 per cent, of those in the table. 
 
 124. Size of the Engine: In obtaining 1 the size of the 
 engine, it will be necessary first to assume the horse power. 
 This had better be taken as a certain ratio to that of the 
 fan. Probably a safe value would be 
 
 H. P. of the engine = 3 H. P. of the fan (66) 
 
 Having obtained the horse power of the engine, it will 
 next be necessary to find the size of the cylinder. Let PI = 
 the absolute initial pressure of the steam in the cylinder, 
 i. e., atmospheric pressure + gage pressure, and r = number 
 of the steam expansions in the cylinder, i. e., reciprocal of 
 the per cent, of cut-off. The cut-off allowed for high speed 
 engines in economical power service, approximates 25 per 
 cent, of the stroke, but in engines for blower work this 
 may be taken at 50 per cent, or half stroke. Find the 
 mean effective pressure, PI, by the formula, 
 
 1 + hyperbolic logarithm of r 
 
 P! = p a back pressure (67) 
 
 r 
 
 Next, let I = length of the stroke in inches and N = number 
 of revolutions per minute and apply the formula 
 
 2p x I AN 
 
 H. P. = (68) 
 
 12 X 33000 
 
 and find A, the area of the cylinder, from which obtain d, 
 the diameter of the cylinder. In applying formula (68) it 
 will b'e necessary to assume I, This, for engines operating 
 blowers, may be taken, 
 
 2 I N = 200 to 400 
 
 Formula 67 assumes that the steam in the cylinder expands 
 according to the hyperbolic curve, pv = p'v'. For values 
 of hyperbolic or Naperian logarithms see Table 3, Appendix. 
 
160 HEATING AND VENTILATION 
 
 It also assumes no loss in the recompression of 
 the steam in the cylinder. Both assumptions are only 
 approximately correct, but the errors are slight and to a 
 certain degree, tend to neutralize each other, hence the 
 final results from this formula are near enough to be used 
 for approximate calculations. For such work as this, r 
 may be taken from 2 to 3, the former being probably pre- 
 ferred. The back pressure should not be taken higher than, 
 say, 5 pounds gage (19.7 pounds absolute), since this is 
 determined by the pressure in the coils carrying exhaust 
 steam. This pressure, in ordinary service, usually drops 
 more nearly to atmospheric pressure. 
 
 In finding the diameter and length of the stroke of the 
 cylinder, it may be necessary to make two or more trial 
 applications before a good size can be obtained. Owing 
 to the fact that the initial steam pressure is frequently 
 low, say not to exceed 40 or 50 pounds, the mean effective 
 pressure is small, thus calling for a cylinder of large 
 diameter. In such cases, the diameter of the cylinder may 
 be greater than the length of the stroke. In cases, how- 
 ever, where high pressure steam is used, say 100 pounds 
 gage, the diameter of the cylinder would be less than the 
 length of the stroke. 
 
 APPLICATION 1. Assume the following to fit the design 
 shown in Figs. 74, 75 and 76: good, dry steam from the 
 boiler to the engine at 100 pounds gage pressure; direct- 
 connected engine to fan, running at 200 revolutions per 
 minute and delivering 2000000 cubic feet of air per hour 
 to the building at one ounce pressure; steam cut-off in the 
 cylinder at one-third stroke and used in the coils at 5 
 pounds gage pressure; find the sizes and horse powers of the 
 fan and engine unit. Applying formulas (64), (65), (66), 
 (67) and (68), 
 
 2000000 
 
 D. of fan = \l =7.5 feet. 
 
 60 X .4 X 200 
 
 (7.5) 5 X (3.3S) 3 X 20 
 
 H. P. of fan = = 10.2 
 
 1000000 
 H. P. of Engine = J X 10.2 = 13.6 
 
 / 1 + 1.0986 \ 
 Pi = 115 I ) 19.9 = 60.5 pounds per 
 
 250 
 
 square inch. Now if 2 I N = 250, then I = = .625 feet = 
 
 400 
 
PLENUM WARM AIR HEATING 161 
 
 13.6 X 12 X 33000 
 
 7.5 inches and A. = = 29 square 
 
 2 X 60.4 X 7.5 X 200 
 
 inches = 6% inches diameter. The engine would be, say, 
 6% inches X 7V 2 inches, at 200 R. P. M. 
 
 APPLICATION 2. Assuming the values as in application 1, 
 excepting that the steam is taken from a conduit main 
 under a pressure of, say, 30 pounds per square inch gage, 
 that 2 I N = 300, and that the steam cut-off in the cylinder 
 is at one-half stroke. Then, as before, D of fan = 7.5 feet; 
 H. P. of fan = 10.2; and H. P. of the engine = 13.6; the 
 mean effective pressure is, however, 
 
 / 1 + .6931 \ 
 Pi = 45 ( J 19.9 = 18. 
 
 2 pounds per sq. in. 
 
 13.6 X 12 X 33000 
 
 and A = = 82 square inches. 
 
 2 X 18.2 X 9 X 200 
 
 Size of the engine would be 10% inches X 9 inches, at 200 
 R. P. M. 
 
 125. Piping Connections around Heater and Engine: 
 
 Where the fans are run by steam power it is considered 
 best to reduce the pressure of the steam by a pressure re- 
 ducing valve before allowing the live steam to enter the 
 coils. Where this reduction is made to 5 pounds or below, 
 it may be entered into the same main with the exhaust 
 steam from the engine, if desired; the back pressure valve 
 on the exhaust steam line providing an outlet to the at- 
 mosphere in case the pressure, for some reason, should run 
 above the 5 pounds allowable back pressure. If the value 
 of the back pressure is increased much above 5 pounds, 
 the efficiency of the engine is seriously affected. In many 
 installations where the condensation from the live steam 
 is desired free from oil, a certain number of coils, only, are 
 tapped for exhaust steam and this condensation trapped to 
 a waste or sewer, the other coils delivering to a receiver 
 of some sort for boiler feed or other purposes as may be 
 required. 
 
 Every system should be fully equipped with pressure 
 reducing valves, back pressure valves, traps and a sufficient 
 number of globe or gate valves on the steam supply, and of 
 gate valves on the returns to make the system flexible and 
 responsive to varying demands, at the will of the operator. 
 Figs. 72 and 73 show a typical plan and elevation for such 
 
162 
 
 HEATING AND VENTILATION 
 
 connections. Some engineers advocate lifting the returns 
 about 20 or 30 inches as shown at A and B to form a wate* 
 seal for each section, thus making them independent in 
 their action. This, in some cases where the coils are very 
 deep, would, no doubt, be a benefit. 
 
 3TBACH PRESS. VA'^VE 
 
 
 k - !&=r===3 5 ==r=^^ 
 
 3EPARATOF1. 
 
 CHECK 
 
 BO/LER 
 
 Fig. 72. 
 
 ' 
 
 * BACK PRCS3 VALVE ifPReSS.Rt 
 
 CX 3TEAM 
 
 L.IVF JT| 
 
 
 
 
 
 
 c 
 
 !t 
 
 
 
 
 
 UJ o * 
 Q "> 
 
 
 
 
 
 
 w <J| 
 
 (C * 
 
 
 
 
 
 I *lu 
 
 .A? c 
 
 1 
 
 1 
 
 1 
 
 1 
 
 ^ ^ 
 
 i 
 
 
 
 
 
 T 
 
 GATC VALV/E5 
 
 4 I""" 
 
 Fig. 73. 
 
 126. Application to School Building: The three follow- 
 ing figures and summary show the results of an ap- 
 plication of the above to a school building. The summary, 
 
PLENUM WARM AIR HEATING 163 
 
 Table XXV, gives in compact form such calculated results 
 as admit of tabulation. Most of the applications throughout 
 Chapters IX, X and XI, also refer to this same building. 
 
 The plans show the double-duct system, with plenum 
 chamber and ducts laid just below the basement floor. The 
 small arrows show the heat registers and vent registers for 
 each room. The same stack which served as a heat carrier 
 to the room on one floor serves as the vent stack for the 
 corresponding room on the floor above, there being, of course, 
 a horizontal cut-off between them. The cut-off at the heat 
 register should be so curved as to throw the current of 
 heated air into the room with the least possible friction or 
 eddy currents, as shown in P ig. 20. 
 
164 
 
 HEATING AND VENTILATION 
 
 TABLE XXV. 
 
 Data Sheet for Figs. 74, 75, 76. 
 
 Room 
 
 n 
 
 Heat loss In B.t.u. per 
 hour from room not 
 counting ventilation. 
 
 Heat loss counting ex- 
 posure 
 
 Per cent, added 
 
 Cubic feet of air needed 
 per hour as a heat 
 carrier 
 
 No. of reg'ters install'd 
 
 II 
 
 H 
 
 ofl 
 
 o3 
 
 <D O 1 
 * 
 
 ^a 
 
 <S> - 1 - 1 
 
 flg 
 
 p 
 
 Size of registers in 
 inches 
 
 Size of stack in inches. 
 
 1. . 
 
 1 
 H 
 
 51,520 
 
 74,200 
 
 
 
 40,185 
 57,876 
 
 2 
 
 322 
 
 18x20 
 
 13x13 
 
 2... 
 
 
 
 8 
 
 1H 
 \% 
 
 l l /2 
 1% 
 
 29,400 
 86,260 
 42,210 
 35,350 
 
 
 
 22,932 
 28,283 
 32,923 
 27,573 
 
 1 
 1 
 1 
 1 
 
 184 
 226 
 263 
 220 
 
 17x18 
 17x21 
 17x25 
 17x21 
 
 17x13 
 17x13 
 17x18 
 17x18 
 
 4... 
 
 
 
 5 
 
 
 
 6... 
 
 
 
 7 
 
 
 
 8... 
 
 1H 
 \% 
 
 \% 
 
 1(5,520 
 16,520 
 42,210 
 
 
 
 12,885 
 12,885 
 32,923 
 
 1 
 1 
 1 
 
 103 
 103 
 263 
 
 13x13 
 13x13 
 17x25 
 
 13x 8 
 13x 8 
 17x13 
 
 9 
 
 
 
 10 
 
 
 
 
 
 
 Totals. 
 
 
 344,190 
 
 
 
 268,466 
 
 
 
 
 
 11 
 
 \ 
 I 1 /* 
 \% 
 
 VA 
 \% 
 
 1V4 
 
 l l A 
 
 81,130 
 115,430 
 40,500 
 55,370 
 63,840 
 48,440 
 51,940 
 23,660 
 23,660 
 63,840 
 
 
 
 63,281 
 99,039 
 34,775 
 47,507 
 54,775 
 89,672 
 40,513 
 19,377 
 18,455 
 49,795 
 
 2 
 4 
 1 
 2 
 2 
 1 
 2 
 1 
 1 
 2 
 
 506 
 792 
 278 
 380 
 488 
 317 
 824 
 155 
 148 
 898 
 
 17x24 
 17x18 
 17x26 
 17x18 
 17x21 
 17x80 
 13x20 
 13x20 
 13x20 
 17x18 
 
 17x13 
 17x13 
 17x18 
 17x13 
 17x18 
 17x13 
 13x18 
 13x18 
 13x13 
 17x13 
 
 12... 
 
 126,973 
 44,583 
 60,907 
 70,224 
 50,862 
 
 10 
 10 
 10 
 10 
 5 
 
 13 
 
 14. . 
 
 15 
 16 
 
 17 
 
 18 
 
 24,843 
 
 5 
 
 19 
 
 20 
 
 
 
 Totals. 
 
 
 540,100 
 
 
 
 467,189 
 
 
 
 
 
 21... 
 22 
 
 23... 
 24 
 25 
 
 26 
 27 
 28. 
 29. 
 30 
 
 l 
 1 
 1 
 1 
 1 
 1 
 
 II A 
 i 
 
 81,130 
 17,150 
 103,460 
 17,150 
 31,900 
 48,580 
 93,030 
 28,420 
 37,380 
 54,110 
 
 
 
 63,281 
 13,377 
 88,764 
 13,377 
 27,447 
 41,682 
 79,819 
 22,163 
 29,156 
 42,206 
 
 2 
 1 
 2 
 1 
 1 
 2 
 2 
 2 
 1 
 2 
 
 506 
 107 
 710 
 107 
 220 
 333 
 638 
 177 
 233 
 338 
 
 17x24 
 13x13 
 21x28 
 13x18 
 17x21 
 13x20 
 17x80 
 13x15 
 17x21 
 13x20 
 
 17x13 
 13x 8 
 17x13 
 18x 8 
 17x13 
 13x18 
 17x13 
 13x 8 
 17x18 
 13x13 
 
 
 
 113,800 
 
 10 
 
 35,189 
 53,438 
 102,333 
 
 10 
 10 
 10 
 
 
 
 
 
 Totals. 
 
 
 598,961 
 
 
 
 421,272 
 
 
 
 
 
 Vent registers taken same size as heat registers. For sizes of 
 engine .fan, heater coils, etc., see applications under these heads. 
 
PLENUM WARM AIR HEATING 
 
 165 
 
166 
 
 HEATING AND VENTILATION 
 
 gs g 
 
 5? PS 
 
 h=| kd |^JD^=J ' t=4"B" 
 
 
 C 
 
 
 .M M M 
 
 Fig. 75. 
 
PLENUM WARM AIR HEATING 
 
 167 
 
 OQ 
 
 M=J i^j ^T-^ UT w* =-: 
 
 >=l ^LELJsa- 
 
 >Jj 
 o a 
 
 st 
 
 I 
 
 Fig. 76. 
 
168 HEATING AND VENTILATION 
 
 REFERENCES. 
 
 References on 3Iechanical Warm Air Heating. 
 
 TECHNICAL BOOKS. 
 
 Snow, Furnace Heating, p. 99. Monroe, Steam Heat. & Vent., p. 
 124. Carpenter, Heating and Ventilating Buildings, p. 333. Hub- 
 bard, Power, Heating and Ventilating, pages 525 and 551. 
 
 TECHNICAL PERIODICALS. 
 
 Engineering Review. Ventilating and Air Washing Appar- 
 atus installed in the Sterling-Welch Building,, Cleveland, 
 O., Jan. 1910, p. 38. Steam Heat, and Vent. Plant Required 
 for Addition to the Hotel Astor, New York, March 1910, p. 27. 
 Heating and Ventilating Plant of the Boston Safe Deposit 
 and Trust Company's Building, C. L. Hubbard, April 1910, p. 
 37. Heating and Ventilating Installation on the Burnet St. 
 School, Newark, N. J., Jan. 1909, p. 20. Heating and Venti- 
 lating the New Jersey State Reformatory, Sept. 1909, p. 
 27. Comparison of Heat, and Vent. Plants Installed in 
 Chicago Schools and Buildings at Various Periods, T. J. 
 Waters, June 1906, p. 14. Heating and Ventilating of Schools, 
 F. G. McCann, June 1906, p. 11. The Heating and Ventilation 
 of Schools, Dec. 1904, p. 1; March 1905, p. 4; Sept. 1905, p. 1; 
 Oct. 1905, p. 5. Note: The last two articles taken together 
 comprise a complete series of the heating and ventilating 
 of the schools of New York City. Machinery. Fans, C. L. 
 Hubbard, Oct. 1905, p. 49; Nov. 1905, p. 109; Dec. 1905, p. 165. 
 Heaters for Hot Blast and Ventilation, C. L. Hubbard, March 
 1907, p. 353. The Heating and Ventilation of Machine Shops, 
 C. L. Hubbard, Sept. 1907, p. 1. Heating and Ventilating 
 Offices in Shops and Factories, C. L. Hubbard, Feb. 1910, p. 
 437. Pans, Machinery's Reference Series, No. 39. The Heat- 
 ing and Ventilating Magazine. Figuring Flow of Air in Metal 
 Pipes by Chart, B. S. Harrison, Dec. 1905, p. 1. Flow of Air 
 in Metal Pipes, J. H. Kinealy, July 1905, p. 3. Friction of 
 Bends in Air Pipes, J. H. Kinealy, Sept. 1905, p. 1. A Test of 
 Hot Blast Heating Coils, March 1905, p. 1. Simplifying the 
 Installation and Operation of School Heating and Ventilating 
 Apparatus, S. R. Lewis, July 1908, p. 10. A Rational For- 
 mula Covering the Performance of Indirect Heating Surface, 
 Perry West, March 1909, p. 1. Charts Showing the Perform- 
 ance of Hot Blast Coils, B. S. Harrison, Oct. 1907, p. 23. The 
 Engineering Magazine. Modern Systems for the Ventilation and 
 Tempering of Buildings, Percival R. Moses, Feb. 1908. Do- 
 mestic Engineering. Practical Suggestions about Blower Systems 
 for Shop Heating, P. R. Still, Vol. 46, No. 4, Jan. 23, 1909 p. 
 100; Vol. 46, Jan. 30, 1909, p. 125. Trans. A. S. H. & V. E. 
 Supplementing Direct Radiation by Fans, Vol. X, p. 286. 
 Methods of Testing Blowing Fans, R. C. Carpenter, Vol. VI. 
 p. 69. Some Experiments with the Centrifugal Fan, W. S. 
 Monroe, Vol. V, p. 117. 
 
CHAPTER XII. 
 
 MECHANICAL VACUUM, STEAM HEATING SYSTEMS. 
 
 127. In Addition to the Brief Discussion of vacuum steam 
 heating as found in Arts. 66 and 67, it will be well to discuss 
 more in detail the various systems by which this heating is 
 accomplished. The advantages to be derived by the positive 
 withdrawal of the air and the condensation from the radi- 
 ators and pipes, compared to the natural circulation of the 
 gravity system, are now too well established to need much 
 discussion. Mains and returns that are too small, horizontal 
 runs of piping that are unevenly laid so as to form air and 
 water pockets, radiators that are only partially heated be- 
 cause of the entrapped air, leaking air and radiator valves, 
 radiators partially filled with condensation and all the accom- 
 panying cracking and pounding throughout many of the grav- 
 ity systems, are sufficient causes for the general public to 
 demand a cure, if such cure can be found. One should not 
 understand by this statement that every mechanical vacuum 
 system is a cure for all the ills in the heating work, for even 
 these systems may be improperly designed. The steam pipes 
 may be too small to supply the radiators, although smaller 
 pipes may be used in this than in the gravity work, the 
 valves may be defective, or the vacuum specialties may be 
 inefficient. Most of the defects in the average plant, however, 
 are because of imperfections in that part of the system 
 from the radiator to the boiler, and all of the first class 
 vacuum systems are planned to meet just these conditions. 
 
 Vacuum systems have other advantages over the gravity 
 work, the principal one being that of lifting the return con- 
 densation to a higher level. This is noticeable in the plac- 
 ing of radiators or coils in basement rooms. Another very 
 important advantage is in the laying out of the heating coils 
 for. shop buildings and manufacturing plants. Low pres- 
 sure gravity coils are limited to a length of about 75 feet. 
 
170 
 
 HEATING AND VENTILATION 
 
 Usually the condensation in a long coil of this kind is very 
 great and requires extra heavy pressure on the steam end 
 to circulate it. The steam follows the line of least resistance 
 and forces the air out of certain pipes and permits it to re- 
 main in others, the differential pressure not being great 
 enough to eliminate all the air and heat the pipes uniformly. 
 As a result of these conditions some of the pipes remain cold 
 and ineffective as prime radiating surface. A vacuum sys- 
 tem, with its positive circulation, increases the differential 
 pressure, removes the air and gives uniform heating effect in 
 coils that are several times as long as can 'be safely supplied 
 by the gravity system. The accumulation of air in the radi- 
 ators and coils is especially noticeable in systems vising ex- 
 haust steam. 
 
 When exhaust steam from engines or turbines is used 
 in a gravity heating system, the back pressure is carried 
 from atmospheric pressure to 10 pounds gage. With the ap- 
 plication of the vacuum system it is possible to maintain this 
 constantly at about atmospheric pressure. It is claimed by 
 some, that it is possible to reduce the pressure in the radiators 
 to such a degree that the pressure in the supply mains will 
 fall considerably below atmosphere. No doubt the specialty 
 
 Fig. 77. 
 
MECHANICAL, VACUUM HEATING 171 
 
 valves may be set so as to do this, but it would scarcely be 
 considered an economical arrangement. 
 
 The principal features of a mechanical vacuum system 
 are shown in Fig. 77. Live steam is conducted to the engine 
 and to the heating main, the latter through a pressure re- 
 ducing valve to be used only when exhaust steam is insuf- 
 ficient. The exhaust steam from the engines and pumps 
 is conducted to the heating main and to the feed water 
 heater. The exhaust steam line opens to the atmosphere 
 through a back pressure valve which is set at the desired 
 pressure for the supply steam. An oil separator shown on the 
 exhaust steam line removes the oil and delivers it to an oil 
 trap. At the entrance to the feed water heater, the exhaust 
 steam passes through a series of baffle plates which remove 
 the oil and entrained water from that part of the steam which 
 enters the heater. A boiler feed pump and a vacuum pump, 
 with the attending valves and governing appliances, com- 
 plete the power room equipment. The steam supply to the 
 heating system is piped to radiators and coils in the ordinary 
 way, with or without temperature control. A thermostatic 
 valve, or patented motor valve, is placed at the return end of 
 each radiator and coil and these returns are then brought to- 
 gether in a common return which leads to a vacuum pump or 
 ejector. The return pipe and specialty valve for any one 
 unit is usually y 2 inch. The combined return increases in 
 size as more radiation is taken on. Horizontal steam mains 
 usually terminate in a drop leg which is tapped to the return 
 8 to 15 inches above the bottom of the leg. Each rise in the 
 system has a drop leg at the lower end of the rise. These 
 points and all other points where condensation may collect 
 are drained through specialty valves to the return. Water 
 supply systems may be tapped for steam and return con- 
 densation the same as any ordinary radiator. Steam is 
 carried in the main at about atmospheric pressure, and just 
 enough vacuum is maintained on the return to insure positive 
 and noiseless circulation. In many cases where special lifts 
 are required, these return systems are run under a negative 
 pressure of 6 to 10 inches of mercury. Under such con- 
 ditions water may be lifted from 6 to 10 feet. Either closed 
 or opened feed water heaters may be used with the layout 
 as given. 
 
 Fig. 78 shows a section through the Marsh vacuum pump 
 which represents a type very generally used in this work. 
 
172 
 
 HEATING AND VENTILATION 
 
 It will be noticed that this pump has a steam operated valve. 
 The automatic governing feature of this valve tends to equal- 
 ize the cylinder pres- 
 sure to meet the vary- 
 ing resistance in the 
 main return of the 
 heating system. Such 
 a pump is handling 
 alternately solid wa- 
 ter and vapors, hence 
 there is great ten- 
 dency of the ordinary 
 pump to race and 
 pound at such times. 
 In its operation the 
 steam enters at A and 
 passes into the space 
 B through the annu- 
 lar opening C be- 
 Fig. 78. tween the reduced 
 
 neck of the valve and 
 
 the bore of the first chest wall. It is thus projected against 
 the inside surface of the valve head before entering into 
 the port and passing to the cylinder. On reaching the 
 cylinder and driving the piston to the right, the reaction of 
 the steam through port D to the opposite side of the valve 
 head, tends to further open the steam port G. The valve 
 then holds a position depending upon the relative strength 
 of the forces which tend to move it in opposite directions, 
 i. e., admission steam which tends to close the valve, and the 
 cylinder steam which tends to open the valve. This 
 is the governing feature. It will be noticed that the pump 
 piston is in two parts and carries steam at admission pres- 
 sure upon the inside. This steam is admitted along the 
 dotted line to the center of the cylinder head, thence through 
 a small tube and packing box to the hollow piston rod, which 
 has a direct connection with the center of the piston. When 
 the piston has moved sufficiently to bring the central space 
 E in line with the duct D, steam is admitted to the right of 
 the piston valve thus forcing it back, cutting off the steam at 
 C, opening up the exhaust to the atmosphere through F and 
 admitting steam to the other end of the cylinder. The action 
 is thus reversed and continuous. Ejectors operated by steam, 
 
MECHANICAL VACUUM HEATING 
 
 173 
 
 water and electricity are also used to produce a vacuum. 
 No comparison is made here of the various systems of pro- 
 ducing vacuum since each gives satisfaction when properly 
 installed. In each case there is a loss of energy but this 
 loss is amply repaid in the added benefits. 
 
 Several patented systems of mechanical vacuum heating 
 are now upon the market. These are in large measure an 
 outgrowth of the original Williames System, patented in 
 1882. Each system is well represented by the above diagram 
 in all particulars concerning the steam and water circu- 
 lation. The chief difference between them is in the thermo- 
 static or motor connection at the entrance to each individual 
 return. 
 
 128. Webster System: In this system a pump is used to 
 produce the vacuum. A special fitting, called a water-seal 
 motor, is used on all radiators, coils and drainage points. 
 Fig. 79 shows a section of one of the valves. Other models 
 are constructed so as to have the outlet in a horizontal di- 
 rection, either parallel with or 90 degrees to the inlet. Jig. 
 80 shows an application of this to a radiator or coil. The 
 dirt strainer is usually placed between the radiator or coil and 
 
 ^HL C 
 
 Fig. 80. 
 
 the motor valve. This strainer collects the dirt and pro- 
 tects from clogging the motor valve. C attaches to the re- 
 turn end of the radiator or coil and L leads to the vacuum 
 pump. O is the central tube, the lower end of which is a 
 valve. A is a hollow cylindrical copper float, the central tube 
 
174 
 
 HEATING AND VENTILATION 
 
 of which fits loosely over spindle B. The function of the 
 cylinder A is to raise the tube G from the seat H and open 
 the discharge to the pump. Ordinarily, the float is down and 
 the central tube valve is resting- upon the seat and cuts off 
 communication with the radiator, excepting as air may 
 be drawn from the radiator down the central tube 
 around the spiral plug. The water of condensation accumu- 
 lating in the radiator or coil passes into the chamber E, 
 sealing the valve, and when sufficient water has accumulated 
 to lift the float, it opens a passageway for a certain amount 
 of the water to be withdrawn to the return. When this 
 water becomes lowered sufficiently, the valve again seats 
 itself and the cycle is completed. This action continues as 
 long as water is present in the radiator. These motor valves 
 are made of three sizes, y 2 inch, % inch and 1 inch. The 
 first is the standard size and has a capacity of approximately 
 200 feet of radiation. 
 
 Fig. 81 shows a ther mo static valve for many years in use 
 by this Company and lately replaced by the above motor 
 valve. It will be seen that the automatic feature in this 
 valve is the compound rubber stalk, 
 which expands and contracts under heat 
 and cold. The adjusting screw at the 
 top permits the valve to be set for any 
 conditions of temperature and pressure 
 within the radiator. The water of 
 condensation passes through a screen 
 and surrounds the rubber stalk. The 
 temperature of the water being less 
 than that of steam, the stalk contracts 
 and the water is drawn through the 
 opening A by the action of the pump. 
 As soon as the water has been removed, 
 steam flows around the stalk and ex- 
 pands it until it closes the seat. This 
 process is a continuous one and auto- 
 matically removes the water from the radiator. The screen 
 serves the purpose of the dirt strainer as mentioned above. 
 A suction strainer, which is very similar to the dirt strainer 
 only larger in capacity, is placed upon the return line next 
 the pump. This fitting usually has a cold water connection 
 to be used at times to assist in producing a more perfect 
 
 Fig. 81. 
 
OF 
 
 A LI FOB? 
 
 ]CHANICAL VACUUM HEATING 
 
 175 
 
 vacuum. The piping system for the automatic control of 
 the vacuum pump is shown in Fig. 82. It will be seen that 
 the vacuum in the return operates 
 through the governor to regu- 
 late the steam supply to the 
 pump cylinder, thus controlling 
 the speed of the pump. 
 
 Occasionally it is desirable to 
 have certain parts of the heating 
 system under a different vacuum. 
 An illustration of this would be, 
 where the radiators within the 
 building were run under a neg- 
 ative pressure of about one 
 pound, and a set of heating coils 
 
 Fig. 82. 
 
 in the basement were to be carried under a negative pressure 
 
 of four pounds. The Web- 
 ster iSystem, type D, Fig. 
 83, meets this condition. 
 The exact difference be- 
 tween the suction pressure 
 and the pressure in the 
 radiators can be varied to 
 suit any condition by the 
 controller valve. A trap 
 and a controller valve 
 should be applied to each 
 line having a different 
 pressure from that in the suction line. 
 
 A modulation valve, for graduating the steam supply to the 
 radiator, has been designed by this Company and may 
 be applied to any Webster Heating System to assist in its 
 regulation. This modulation valve serves to graduate the 
 steam supply to the radiators so that the pressure may be 
 maintained at any point to suit the required heat loss from the 
 building. 
 
 129. VamAuken System: In this system, as in the pre- 
 vious one, the vacuum in the return main is produced by a 
 vacuum pump which is controlled by an especially designed 
 governor. The automatic valves which are placed on the 
 radiators, coils and other drainage points along the system, 
 are called Belvac Thermoflres, and are shown in section by 
 Fig. 84. This valve is automatic and removes the water of 
 
176 
 
 HEATING AND VENTILATION 
 
 Fig-. 84. 
 
 condensation by the controlling ac- 
 tion of a float. It is connected to the 
 radiator or coil at K and to the vacu- 
 um return pipe at L. The water of 
 condensation is drawn through the 
 return pipe into chamber D until it 
 reaches the inverted weir E which 
 gives it a water seal. It is thence 
 drawn upward into space D until it 
 overflows into the float chamber AA, 
 where it accumulates until the line 
 of flotation is reached. When the 
 float C lifts, the valve seat at B opens 
 and allows the water 'to escape into 
 the vacuum return pipe. After the 
 removal of the w^ater the float again settles on seat B until 
 sufficient water accumulates in the float chamber to again 
 lift it, when the cycle is repeated. 
 
 The air contained in the radiators or coils is drawn 
 through the return and up through chamber D into the top of 
 the float chamber. Here its direction follows arrows GO, 
 being drawn through the small opening in the guide-pin at 
 F, down through the hollow body of the copper float and 
 valve seat B, into the vacuum return. This removal of air is 
 continuous regardless of the amount of water present. The 
 by-pass /, when open, allows all dirt, coarse sand or scale 
 to pass directly into the vacuum return, thus cleaning the 
 valve. By opening the by-pass /, only part way, the con- 
 tents of chamber A may be emptied into the vacuum return 
 without interfering with the conditions in space D. The 
 ends of the float are symmetrical, hence it will work either 
 way. The thermofires are made in four standard sizes of 
 outlets, two having y 2 inch and two having % inch outlets. 
 These valves have capacities of 125, 300, 550 and 1200 square 
 feet of radiation respectively. 
 
 Drop legs, strainers, governors and other specialties 
 usually provided by such comipanies are supplied in addition 
 to the thermofires. When a differential vacuum is to be ob- 
 tained a special arrangement of the piping system is planned 
 to cover this point. The piping connections around the auto- 
 matic pump governor are the same as are shown in Fig. 82. 
 
MECHANICAL VACUUM HEATING 
 
 177 
 
 130. Automatic Vacuum System: In this system the 
 automatic vacuum valve, which takes the place of the motor valve 
 and thermofire in the two preceding systems, is shown in 
 Pig. 85. K is the entrance to the radiator and L to the 
 
 vacuum return. Screen V 
 prevents scale and dirt 
 from entering the valve. 
 By-pass E is for emerg- 
 \K ency use in draining off 
 accumulated water and 
 dirt, should the valve clog. 
 With such an adjust- 
 ment the bonnet of the 
 valve may be removed 
 for inspection without 
 overflowing. Before the 
 steam is turned on in the 
 
 radiator the float is tipped, as shown in the figure, making 
 a small wedge shaped opening through which the vacuum 
 can pull on the radiator. When steam is admitted to the radi- 
 ator, condensation flows into the valve, lifting the float and 
 sealing the outlet against the passage of steam. As the valve 
 continues to fill with water the float is lifted, and water 
 passes to the vacuum return. As the water is drawn off the 
 float falls and reseats on the nipple when about y 2 inch of 
 
 water remains in the valve, 
 thus maintaining the water 
 seal. Fig. 86 shows the 
 piping connections around 
 the automatic pump gov- 
 ernor. It will be seen that 
 this connection differs from 
 that of the Webster and 
 Van Auken Systems, in that 
 the pressure in the return 
 main controls the flow of 
 injection water into the 
 
 Fig. 
 suction strainer. 
 
 131. Paul System: Referring to Art. 67 it will be seen 
 that the Paul System is essentially a one-pipe system, with the 
 vacuum principle attached to the air valve. Its use is not 
 restricted to the one-pipe radiator, since it may be applied 
 
178 
 
 HEATING AND VENTILATION 
 
 to the two-pipe radiator as well. The advantage to be gained, 
 however, when applied to the former, is much greater than 
 in the latter because of the greater possibility of air clog- 
 ging the one-pipe radiator. This one fact has largely deter- 
 mined its field of operation. This system differs from the 
 ones just mentioned in two essential points; first, the vacu- 
 um effect is applied at the air valve and the water of con- 
 densation is not moved by this means; second, the vacuum 
 effect is produced by the aspirator principle using water, 
 steam or compressed air, as against the pumps used by the 
 other companies. The same principle may also be applied to 
 the tank receiving the condensation. By this means it is 
 possible to remove all the air in the system and to produce 
 a partial vacuum if necessary. Ordinarily the vacuum is 
 supposed to extend only as far as the air valve at the radi- 
 ator. If desired, however, this valve may be adjusted so 
 that the vacuum effect may be felt within the radiator, and 
 in some cases mlay extend into the supply main. Many 
 modifications of the Paul System are being used. In its la- 
 test development, the layout of the system for large plants, is 
 
 Fig-. 87. 
 
MECHANICAL VACUUM HEATING 179 
 
 about the same as that shown in Fig 77, where all of the 
 principal pieces of apparatus that go to make up the power 
 room equipment are present. Fig. 87 shows a typical vacuum 
 connection between one-pipe and two-pipe radiators and the 
 exhauster. This diagram shows the discharge leading to a 
 tank, sewer or catch basin. If exhaust steam were used, the 
 discharge would probably lead into the steam supply to one 
 or more of the radiators and then into the atmosphere. 
 Where electric current can be had this exhausting may be 
 done by the use of an electric motor. A specially designed 
 thermostatic air valve is supplied by the Company to be 
 used on this system. 
 
 Other vacuum systems, each having a full line of specialty 
 appliances, might be mentioned here but the above are con- 
 sidered sufficient. 
 
180 HEATING AND VENTILATION 
 
 REFERENCES. 
 
 References on Mechanical Vacuum Heating. 
 
 TECHNICAL BOOKS. 
 
 Snow, Principles of Heat., Chap. XL. Carpenter, Heating <& 
 Vent. Blags., p. 285. Hubbard, Power, Heat. & Ventilation, p. 568. 
 TECHNICAL PERIODICALS. 
 
 Engineering Review. Steam Heating Installation in the 
 Biology and Geology Building 1 and the Vivarium Building, 
 Princeton University (Webster System), Jan. 1910, p. 27. 
 Steam Heating and Ventilating Plant Required for Addition 
 to Hotel Astor (Paul System), March 1910, p. 27. Heating 
 Four Store Buildings at Salina, Kan., (Moline System, vacuum 
 vapor), April 1910, p. 45. Steam Heating System for Henry 
 Doherty's Mill, Paterson, N. J., May 1910, p. 37. Heating 
 Residences at Fairfield, Conn., (Bremen's System of Vapor 
 Heating), June 1910, p. 52. Heating Residence at Fleming- 
 ton, N. J., (Vapor- Vacuum System), July 1910, p. 43. Heating 
 System installed in the Haynes Office Building, Boston, (Web- 
 ster Modulation System), Aug. 1910, p. 44. Heating the 
 Silversmith's Building, New York, (Thermograde System), 
 Jan. 1908, p. 8. Heating System in the New Factory of Jen- 
 kins' Bros., Ltd., Montreal, Canada (Positive Differential 
 System), Dec. 1907, p. 14. The Railway Review. Vacuum Ventila- 
 tion for Street Cars, Oct. 23, 1909, p. 948. 
 
CHAPTER XIII. 
 
 DISTRICT HEATING OR CENTRALIZED HOT WATER 
 AND STEAM HEATING. 
 
 GENERAL. 
 
 132. Heating Residences and Business Blocks from a cen- 
 tral station is a method that is being employed in many cities 
 and towns throughout the country. The centralization of 
 the heat supply for any district in one large unit has an 
 advantage over a number of smaller units in being able to 
 burn the fuel more economically, and in being able to re- 
 duce labor costs. It has also the advantage, when in con- 
 nection with any power plant, of saving the heat which 
 would otherwise go to waste in the exhaust steam and stack 
 gases, by turning it into the heating system. The many 
 electric lighting and pumping stations around the country 
 give large opportunity in this regard. Since the average 
 steam power plant is very wasteful in these two particulars, 
 any saving that might be brought about should certainly be 
 sought for. On the other hand, however, a plant of this 
 kind has the disadvantage in that it necessitates transmitting 
 the heating medium through a system of conduits, which 
 generally is a wasteful process. The failure of many of the 
 pioneer plants has cast suspicion upon all such enterprises 
 as paying investments, but the successful operation of many 
 others shows the possibilities, where care is exercised in 
 their design and operation. 
 
 133. Important Considerations in Central Station Heat- 
 Ing: In any central heating system, the following consider- 
 ations will go far towards the success or the" failure of the 
 enterprise: 
 
 First. There should be a demand for the heat. 
 Second. The plant should be near to the territory heated. 
 Third. There should be good coal and water facilities at 
 the plant. 
 
182 HEATING AND VENTILATION 
 
 Fourth. The quality of all the materials and the instal- 
 lation of the same, especially in the conduit concerning in- 
 sulation, expansion and contraction, and durability, are 
 points of unusual importance. 
 
 Fifth. The plant must be operated upon an economical 
 basis, the same as is true of other plants. 
 
 Sixth. The load-factor of the plant should be high. This 
 is one of the most important points to be considered in com- 
 bined heating and power work. The greater the proportion 
 of hours each piece of apparatus is in operation, to the total 
 number of hours that the plant is run, the greater the plani. 
 efficiency. The ideal load-factor is where all of the apparatus 
 is running at full load all the time. 
 
 The average conduit radiates a great deal of heat, hence, 
 the nearer the plant to the heated district the greater the 
 economy of the system. Likewise a location near a railroad 
 minimizes fuel costs; and good water, with the possibility 
 of saving the water of condensation from the steam; all serve 
 to the increased economy of the plant. It is to be expected 
 that even a well designed plant, unless safeguarded against 
 ills as above suggested, would soon succumb to inevitable 
 failure. 
 
 Two types of centralized heating plants are in use, hot 
 water and steam. Each will be discussed separately. In the 
 discussion of either system, certain definite conditions will 
 have to be met. First of all, there should be a demand in 
 that certain locality for such a heating system, before the 
 plant can be considered a safe investment. To create a de- 
 mand requires good representatives and a first class resi- 
 dence or business district. When this demand is obtained 
 the plan of the probable district to be heated will first be 
 platted and then the heating plant will be located. In many 
 cases the heating plant will be an added feature to an al- 
 ready established lighting or power plant and its location 
 will be more or less a predetermined thing 1 . 
 
 In addition to these material and financial features just 
 mentioned, one must consider the legal phases that always 
 come up at such a time. These relate chiefly to the franchise 
 requirements that must be met before occupying the streets 
 with conduit lines, etc. All of these considerations are a 
 part of the one general scheme. 
 
DISTRICT HEATING 183 
 
 134. The Scope of the \Vork in Central Station Heating 
 may be had from the following outline: 
 
 { Exhaust Steam Heaters 
 Live Steam Heaters 
 
 CENTRAL STA- 
 
 Hot Water Heating 
 
 Heating Boilers 
 
 by use of. 
 
 I Economizers 
 
 Injectors or 
 
 TION HEATING 
 
 Co-Mingle rs 
 
 Exhaust Steam 
 . Steam Heating. 
 
 Live Steam 
 
 In the hot water system the return water at a lowered tem- 
 perature enters the power plant, is passed through one or 
 more pieces of apparatus carrying live or exhaust steam, or 
 flue gases, and is raised in temperature again to that in the 
 outgoing main. From the above, a number of combinations 
 of reheating can be had. Any or all of the units may be put 
 in one plant and the piping system so installed that the water 
 will pass through any single unit and out into the main; or, 
 the water may be split and passed through the units in par- 
 allel; or, it may be made to pass through the units in series. 
 All of these combinations are possible, but not practicable. 
 In most plants, two or three combinations only are provided. 
 In the existing plants the order of preference seems to be, 
 exhaust steam reheaters, economizers, heating boilers, inject- 
 ors or co-minglers, and live steam heaters. 
 
 All of the above pieces of reheating apparatus operate 
 by the transmission of heat through metal surfaces, such as 
 brass, steel or cast iron tubes, excepting the co-mingler, this 
 being simply a barometric condenser in which the exhaust 
 steam is condensed by the injection water from the return 
 main, the mixture being drawn directly into the pumps. 
 
 The objection to the tube transmission is the lime, mud 
 and oil deposit on the tube surfaces, thus reducing the rate 
 of transmission and requiring frequent cleaning. The ob- 
 jections to the co-minglers are, first, that the pumjp must 
 draw hot water from the condenser and second, that a certain 
 amount of the oil passes into the heating line. With per- 
 
184 HEATING AND VENTILATION 
 
 fected apparatus for removing the oil, the co-mingler will 
 no doubt supersede, to a large degree, the tube reheaters in 
 hot water heating. 
 
 In the steam system the proposition is very much simplified. 
 The exhaust steam passes through one or more oil separating 
 devices and is then piped directly to the header leading 
 to the outgoing main. Occasionally a connection is made from 
 tuis line to a condenser, such that the steam, when not used 
 in the heating system, may be run directly to the condenser. 
 These pipe lines, of course, are all properly valved so that the 
 current of steam may easily be deflected one way or the 
 other. In addition to this exhaust steam supply, live steam 
 is provided from the boiler and enters the header through 
 a pressure reducing valve. In any case when the exhaust 
 steam is insufficient the supply may be kept constant by auto- 
 matic regulation on the reducing valve. 
 
 In selecting between hot water and steam systems the 
 preference of the engineer is very largely the controlling 
 factor. The preference of the engineer, however, should be 
 formed from facts and conditions surrounding the plant, and 
 should not come from mere prejudice. The following points 
 are some of the important ones to be considered: 
 
 First cost of plant installed. This is very much in favor of 
 the steam system in all features of the power plant equip- 
 ment, the relative costs of the conduit and the outside work 
 being very much the same. 
 
 Cost of operation. This is in favor of the hot water sys- 
 tem because of the fact that the steam from the engines 
 may be condensed at or below atmospheric pressure, while 
 the exhausts from the engines in the steam systems must 
 be carried from five to fifteen pounds gage, which naturally 
 throws a heavy back pressure upon the engine piston. 
 
 Pressure in circulating mains. This is in favor of the steam 
 system. The pressure in any steam radiator will be only 
 a few pounds above atmosphere, while in a hot water sys- 
 tem, connected to high buildings, the pressure on the first 
 floor radiators near the level of the mains, becomes very 
 excessive. The elevation of the highest radiator in the 
 circuit, therefore, is one of the determining factors. 
 
 Regulation. It is easier to regulate the hot water system 
 without the use of the automatic thermostatic control, since 
 the temperature of the water is maintained according to a 
 
DISTRICT HEATING 185 
 
 schedule, which fits all degrees of outside temperature. When 
 automatic control is applied, this advantage is not so marked. 
 
 Returning the icater to the power plant. In most steam plants 
 the water of condensation is passed through indirect heaters, 
 to remove as much of the remaining heat as possible and 
 is then run to the sewer. This procedure incurs a consider- 
 able loss, especially in cold weather when the feed water 
 at the power plant is heated from low temperatures. This 
 point is in favor of the hot water system. 
 
 Estimating charges for heat. This is in favor of the steam 
 system since, by meter measurement, a company is able to 
 apportion the charges intelligently. The flat rate charged for 
 water heating and for some steam heating is in many cases 
 a decided loss to the company. 
 
 135. Conduits: In installing conduits for either hot 
 water or steam systems the selection should be made after 
 determining, first, its efficiency as a heat insulator; second, 
 its initial cost; third, its durability. Other points that must 
 be accounted for as being very essential are: the supporting, 
 anchoring, grading and draining of the mains; provision for 
 expansion and contraction of the mains; arrangements for 
 taking off service lines at points where there is little move- 
 ment of the mains; and the draining of the conduit. 
 
 Some conduits may be installed at very little cost and 
 yet may be very expensive propositions, because of their in- 
 ability to protect from heat losses; while, on the other hand, 
 some of the most expensive installations save their first 
 cost in a couple of years' service. Many different kinds of 
 insulating materials are used in conduit work such as mag- 
 nesia, asbestos, hair felt, wool felt, mineral wool and air cell. 
 Each of these materials has certain advantages and under cer- 
 tain conditions would be preferred. It is not the real purpose 
 here to discuss the merits of the various insulators, because 
 the quality of the workmanship in the conduit enters into the 
 final result so largely. The different ways that pipes may 
 be supported and insulated in outside service will be given, 
 with general suggestions only. E ig. 88 shows a few 
 of the many methods in common use. A very simple conduit 
 is shown at A. This is built up of wood sections fitted end 
 to end, then covered with tarred paper to prevent surface 
 water leaking in and bound with straps. The pipe either is a 
 
186 HEATING AND VENTILATION 
 
 loose fit to the bore and rests upon the inner surface, or is 
 supported on metal stools, driven into the wood or merely 
 resting upon it. These stools hold the pipe concentric with 
 the inner bore of the log. With much movement of the 
 pipe endwise, from expansion and contraction, these stools 
 should not be used unless they are loose and have a wide 
 surface contact with the wood. A metal lining with the pipe 
 resting directly upon it is considered good. The conduit is 
 laid to a good straight run in a gravel bed and usually over 
 a small tile drain to carry off the surface water, excepting 
 as this drain is not necessary in sections where there is good 
 gravel drainage. The insulation in A. is only fair. The air 
 space around the pipe, however, is to be commended. B is 
 an improvement over A and is built up of boards notched 
 at the edges to fit together. The materials used, from the 
 outside to the center, are noted on the sketch beginning 
 with the top and reading down. This covering is in general 
 use and gives good satisfaction from every standpoint. C 
 shows a good insulation and supports the pipe upon rollers 
 at the center of a line of halved, vitrified tile. The lower 
 half of the tile should be graded and the pipe then run upon 
 the rollers, after which it may be covered with some pre- 
 pared covering and the remaining space next the tile filled 
 with asbestos, mineral wool or other like material. D shows 
 the same adapted to cellar work. Occasionally two pipes are 
 run side by side, main and return, in which case large halved 
 tiles may be used as in E, having large metal supports curved 
 on the lower face to fit the tile. If these supports are not 
 desired the same kind of straight tiles may be used with a 
 Tee tile inserted every 8 to 12 feet having the bell looking 
 down as in F. In this bell is built a concrete setting with 
 iron supports for the pipes which run on rollers, over a rod. 
 These rollers are sometimes pieces of pipes cut and reamed, 
 but are better if they are cast with a curvature to fit the 
 pipes to be supported. This form of conduit, when drained 
 to good gravel, gives first class service. G, H and / show 
 box conduits with two or more thicknesses of % inch boards 
 nailed together for the sides, top and bottom. The bottom 
 of the conduit is first laid and the pipe is run. The sides 
 are then set in place and the insulating material put in, 
 after which the top is set and the whole filled in. 7 shows 
 
DISTRICT HEATING 
 
 187 
 
 
 Fig-. 88. 
 
188 HEATING AND VENTILATION 
 
 the best form of box, since with the air spaces this is a 
 very good insulator. All wood boxes are very temporary, 
 hence, brick and concrete are usually preferred. K is a 
 conduit with 8-inch brick walls covered with flat stones or 
 halved glazed tiles cemented to place to protect from sur- 
 face leakage. The bottom of the conduit has supports built 
 in every 8 to 12 feet, and between these points the conduit 
 drains to the gravel. The usual rod and roller here serve 
 as pipe supports. The pipe is covered with sectional cover- 
 ing and the rest of the space may or may not be filled with 
 wool or chips, as desired. L shows the sectional covering 
 omitted and the entire conduit filled with mineral wool, hair 
 felt or asbestos, and ashes. M has the supporting rod built 
 into the sides of the conduit and has the bottom of the con- 
 duit bricked across and cemented to carry the leaks and 
 drainage to some distant point. N shows a concrete bot- 
 tom with brick sides, having the pipe supported upon cast- 
 iron standards. The latest conduit has concrete slabs for 
 bottom and sides and has a reinforced concrete slab top. 
 This conies as near being permanent as any, is reasonable 
 in price, and when the interior is filled with good non-con- 
 ducting material, or when the pipe is covered with a good 
 sectional covering, it gives fairly high efficiency. 
 
 All conduits should be run as nearly level as possible 
 to avoid the formation of air pockets in the main. Any un- 
 usual elevation in any part of the main may require an air 
 vent being placed at the uppermost point of the curve, other- 
 wise air may form in such quantities as to retard circulation. 
 
 136. Layout of Street Mains and Conduits: No definite 
 information can be given concerning the layout of street 
 mains, because the requirements of each district would call 
 for independent consideration. The following general sug- 
 gestions, however, can be noted as applying to any hot 
 water or steam system: 
 
 Streets to be used. Avoid the principal streets in the city, 
 especially those that are paved; alleys are preferred because 
 of the minimum cost of installation and repairs. 
 
 Cutting of the Mains. Do not cut the main trunk line for 
 branches more often than is necessary. Provide oc- 
 casional by-pass lines between the main branches at the most 
 important points in the system, so that, if repairs are being 
 
DISTRICT HEATING 
 
 189 
 
 made on any one line, the circulation beyond that point may 
 be handled through the by-pass. Such by-pass lines should 
 be valved and used only in case of emergency. 
 
 Offsets and Expansion Joints. Offsets in the lines hinder 
 the free movement of the water and add friction head to the 
 pumps; hence, in water systems, the number should be re- 
 duced to a minimum. Long radius bends at the corners re- 
 duce this friction. Offsets are especially valuable to take 
 up the expansion and contraction of the piping without the 
 aid of expansion joints. This is illustrated in !E ig. 89, where 
 anchors are placed at A, and the gradual bending of the 
 pipes at each corner makes the necessary allowance. The 
 expansion in wrought iron is about .00008 inch per foot per 
 degree rise in temperature; hence in a hot water main the 
 linear expansion between and 212 is .017 inch per foot of 
 length or 1.7 inches for each 100 feet of straight pipe. In 
 hot water heating systems, however, the temperature of thid 
 pipe should never be less than, say, 50, which would cause 
 an expansion from hot to cold of only .013 inch per foot, or 
 1.3 inches for each 100 feet of straight pipe. In a steam main 
 the temperature may vary anywhere from 50 to 300, making 
 a lineal expansion of .02 inch per foot of length or 2 inches 
 for each 100 feet of straight pipe. As here shown the 
 
 movement from the anchor 
 at A toward B may be absorbed 
 by the swinging of the pipe 
 about O. B.B. should therefore 
 be as long as possible, say one 
 full block, to avoid unduly 
 straining the pipe at the 
 joints. Allowing a maximum 
 movement of 6 inches for 
 
 Fig. 89. 
 
 each expansion joint, the anchors would be spaced 500 and 
 300 feet center to center respectively, fcr hot water and 
 steam mains. These figures would seldom be exceeded, and 
 in some cases would be reduced, the spacing depending 
 upon the type of expansion joint used. Ordinarily, 400 feet 
 spacing would be recommended for hot water and 300 feet 
 for steam. If the city layout meets this value fairly well, 
 then the expansion joints and anchors may be made to 
 alternate with each other, one each to every city block. 
 
190 HEATING AND VENTILATION 
 
 Fig. 90. 
 
DISTRICT HEATING 191 
 
 A few of the expansion joints in common use are shown 
 In Fig. 90. A is the old slip and packed joint. This joint 
 causes very little trouble except that it needs repacking 
 frequently. It is very effective when properly cared for. 
 The slip joint should have bronze bearings on both the 
 outside of the plug and the lining of the sleeve. The ends 
 of the plug and sleeve may be screwed for small pipes, 
 or flanged for large ones. B shows an improved type of 
 slip joint, having a roller bearing upon a plate in the 
 bottom of the conduit, and plugs bearing against metal 
 plates along the sides of the conduit to keep it in line. G 
 and D show other slip joints very similar to A and B. C 
 has one ball and socket end to adjust the joint to slight 
 changes in the run of the pipe, and D has two packings 
 enclosing the plug to give it rigidity. The drainage in 
 each case is taken off at the bottom of the casting. E 
 has two large flexible disks fastened to the ends of the 
 pipe and separated from each other by an annular ring 
 casting. These disks are frequently corrugated, are usually 
 of copper and are very large in diameter so that the pipe 
 has considerable movement without endangering the metal 
 in the disks. F has a corrugated copper tube fastened at 
 the ends to the pipe flanges. This is protected from ex- 
 cessive internal pressure by a straight tube having a sli- 
 ding fit to the inside of the flanges, thus allowing for end 
 movement. G is very similar to E. It has, however, only 
 one copper disk. This disk is enclosed in a cast iron case- 
 ment, one side of which is open to the atmosphere, the 
 other side having the same pressure as within the pipe. 
 H is very similar to E, having two copper diaphragms to 
 take up the movement. These diaphragms flex over rings 
 with curved edges and are thus protected somewhat against 
 failure. I shows a copper U tube which is sometimes used. 
 This is set in a horizontal position and the expansion and 
 contraction is absorbed by bending the loop. In all these 
 joints those which depend upon the bending of the metal 
 require little attention except where complete rupture oc- 
 curs. In old plants, however, the rupturing of these dia- 
 phragms is of frequent occurrence. The packed joint re- 
 quires attention for packing several times in the year, but 
 very seldom causes trouble other than this. 
 
192 
 
 HEATING AND VENTILATION 
 
 Anchors. In any long run of pipe, where the expansion 
 and contraction of the pipe causes it to shift its position very 
 much, it is necessary to anchor the pipe at intervals so as to 
 compel the movement toward certain desired points. The 
 anchor is sometimes combined with the expansion joint, in 
 which case the conduit work is simplified. See Fig. 91. 
 
 Service pipes to residences are taken off at or near the 
 anchors. All condensation drains in steam mains are like- 
 wise taken off at such points. 
 
 Fig. 91. 
 
 Valves. All valves on water systems should be straight- 
 way gate valves. Valves on steam systems should be gate 
 valves on lines carrying condensation, and renewable seat 
 globe valves on the steam lines. Valves should be placed on 
 the main trunk at the power plant, on all the principal 
 branch mains as they leave the main trunk, on all by-pass 
 lines, on all the service mains to the houses, and at such 
 important points along the mains as will enable certain 
 portions of the heating district to be shut off for repairs 
 without cutting out the entire district. 
 
DISTRICT HEATING 
 
 193 
 
 Manholes. Manholes are placed at important points along 
 the line to enclose expansion joints and valves. These man- 
 holes are built of brick or concrete and covered with iron 
 plates, flag stones, slate or reinforced concrete slabs. Care 
 must be exercised to drain these points well and to have the 
 covering strong enough to sustain the superimposed loads. 
 
 137. Typieal Design for Consideration: In discussing dis- 
 trict heating, each important part of the design work will 
 be made as general as possible and will be closed by 
 an application to the following concrete example which re- 
 fers to a certain portion of an imaginary city, Fig. 92, 
 as available territory. A city water supply and lighting 
 plant is located as shown, with lighting and power units ag- 
 gregating 475 K. W., city water supply pumps aggregating 
 3000000 gallons maximum capacity, and smaller units re- 
 quiring approximately 15 per cent, of the amount of 
 steam used by the larger lighting units, all as stated in gen- 
 eral instructions. Chapter XVI. It is desired to redesign 
 this plant and to add a district heating system to it; the same 
 
 Fig. 92. 
 
194 
 
 HEATING AND VENTILATION 
 
 to have all the latest methods of operation and to be of such a 
 size as to be economically handled. Fig. 99 shows the essen- 
 tial details of the finished plant. , 
 
 138. Electrical Output and Exhaust Steam Available for 
 Heating Purposes Prom the Power Units: In the operation 
 of such a plant, one of the principal assets is the amount of 
 exhaust steam available for heating purposes. The amount 
 may be found for any time of the day or night by construct- 
 ing a power chart as in Pig. 93, and a steam consumption 
 chart as in Fig. 94. Referring to Fig. 93, the, values here 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ilA 
 
 
 
 
 -- 
 
 -- 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 .". 
 
 -ISA 
 
 --" 
 
 J - 
 
 _-, 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 l_ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 > 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 200 o 
 
 
 
 
 
 
 
 
 
 ~v>y 
 
 " P 
 
 |IN 
 
 .TO 
 
 1 V 
 
 i- ^ 
 
 .. 
 
 
 
 
 
 
 
 
 
 
 - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ... 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 / 
 
 * 
 
 2. 
 1. 
 
 / 
 
 1 -. 
 
 4 
 
 I 
 
 " t 
 
 A 
 
 
 1 
 
 * 
 
 / 
 
 a i 
 
 / 
 1 
 
 ; / 
 
 j 
 
 , 
 
 . 
 
 I- > 
 
 f 
 
 *' 
 
 ' t 
 
 3 '; 
 
 / 
 
 / 
 
 / /* 
 Pf 
 
 Fig. 93. 
 
 given are assumed, for illustration, to be those recorded at 
 the switch board of the typical plant on a day when heavy 
 service is required. The curves show that the 75 KW. unit 
 runs from 12 P. M. to 7 A. M. and from 6 P. M. to 12 P. M. 
 with an output of 25 KW. It also runs from 7 A. M. to 10 A. 
 M. and from 4 P. M. to 6 P. M. under full load. The 150 KW. 
 unit runs from 4 A. M. to 7 A. M. with an output of 100 KW. 
 and then increases to 125 KW. for the entire time until 6 P. M. 
 when it is shut down. The 250 KW. unit is started up at 7 
 A. M. and runs until 6 P. M. under full load, when the load 
 drops off to 150 KW. and continues until 10 P. M. when the 
 unit is shut down, leaving only the 75 KW. unit running. The 
 heavy solid line shows all the power curves superimposed 
 one upon the other. Having given the KW. output, the gen- 
 
DISTRICT HEATING 
 
 195 
 
 eral formula for determining the horse power of the engines is 
 
 KW. X 1000 
 
 I. H. P. = 
 
 (69) 
 
 746 X E X E' 
 
 where E and E' are the efficiencies of the generator and en- 
 gine respectively. If we assume the efficiency of the gener- 
 ator to be 90 per cent., and that of the engine to be 92 per 
 cent., then formula 69 becomes, 
 
 KW. X 1000 
 
 /. H. P. = = approx, 1.62 KW. (70) 
 
 746 X .90 X .92 
 
 Assuming that the 250 KW. unit consumes 24 pounds, the 
 150 KW. unit 32 pounds, and the 75 KW. unit 32 pounds of 
 steam per /. H. P. hour respectively, when running under 
 normal loads, we have the total steam consumed in the three 
 units at any time shown by the lower curve in Fig. 94. 
 
 zzooo - 
 
 
 
 
 
 
 
 
 
 i 
 
 
 
 
 
 
 1 ! 
 
 
 
 
 
 
 H 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 | 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 -,-.-.. 
 
 
 
 
 
 
 
 
 tut 
 
 
 
 
 
 
 
 
 1 8000 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 o 
 xooojj 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 IOOOOQ 
 
 
 
 
 
 
 
 
 
 
 ftT 
 
 |p^f- 
 
 rf 
 
 liiajjMf^Ti 
 
 {M 
 
 
 
 
 
 
 b. 
 
 
 
 
 YS 
 
 8000 R- 
 
 
 
 
 
 
 __ 
 
 
 
 
 
 
 
 at 
 
 
 
 
 
 
 
 3 
 
 
 
 
 
 
 
 
 
 
 
 PU 
 
 VI 
 
 B 
 
 
 
 
 
 
 
 
 
 
 
 
 4oco - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2000 ~ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 4_ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 _j , 
 
 
 
 
 !=^Tr 
 
 rss; 
 
 rn a.n n . f.n. p. 
 
 HOURS. 
 
 Fig. 94. 
 
 The upper curve shows the 15 per cent, added allowance for 
 the smaller units. The values assumed for efficiencies and 
 the values for steam consumption are reasonable, and may be 
 used if a more exact figure is not to be had. 
 
 It will be seen that the maximum steam consumption in 
 the generating units in the power plant is 23100 pounds per 
 hour and the minimum is 1490 pounds per hour. These two 
 
196 HEATING AND VENTILATION 
 
 amounts, then, together with the exhaust steam from the 
 circulating pumps on the heating system, if a hot water 
 system is installed, and that from the pumps in the city 
 water supply, will determine the capacity of the exhaust 
 steam heaters on the hot water supply and the capacity of 
 the boilers or economizers to be used as heaters when the 
 exhaust steam is deficient. 
 
 139. Amount of Heal Available for Heating: Purposes 
 in Exhaust Steam, Compared with That in Saturated Steam 
 at the Pressure of the Exhaust: To study the effect of ex- 
 haust steam upon heating problems and to determine, if 
 possible, the theoretical amount of heat given off with 
 the exhaust steam under various conditions of use, let us 
 make several applications: first, to a simple high speed 
 non condensing engine using saturated steam; second, to 
 a compound Corliss non condensing engine using saturated 
 steam; third, to the first application when superheated 
 steam is used instead of saturated steam; and fourth, to a 
 horizontal reciprocating steam pump. Assume the follow- 
 ing safe conditions: Case one boiler pressure 100 pounds 
 gage; pressure of steam entering cylinder 97 pounds gage; 
 quality of steam at cylinder 98 per cent.; steam consump- 
 tion 34 pounds per indicated horse power hour; one per 
 cent, loss in radiation from cylinder; and exhaust pressure 
 2 pounds gage. Case 2 boiler pressure 125 pounds gage; 
 pressure at high pressure cylinder 122 pounds gage; quality 
 of steam entering high pressure cylinder 98 per cent.; 
 steam consumption 22 pounds per indicated horse power 
 hour; 2 per cent, loss in radiation from cylinders and re- 
 ceiver pipe, and exhaust pressure 2 pounds gage. Case 
 three same as case one with superheated steam at 150 de- 
 grees of superheat; Case four as stated later. 
 
 The number of B. t. u. exhausted with the steam, in 
 any case, is the total heat in the steam at admission, minus 
 the heat radiated from the cylinder, minus the heat ab- 
 sorbed in actual work in the cylinder. 
 
 High Speed Engine. Case One. Let r heat of vapor- 
 ization per pound of steam at the stated pressure, 'a? = qual- 
 ity of the steam at cut off, q heat of the liquid in the 
 steam per pound of steam, and W 8 = pounds of steam per 
 
DISTRICT HEATING 197 
 
 indicated horse power hour. From this the total number 
 of B. t. u. entering the cylinder per horse power hour is 
 
 Total B. t. u. W s (xr + q) (71) 
 
 From Peabody's Steam tables r = 881, x = .98 and q = 307; 
 then if W a = 34, Initial B. t. u. = 34 (.98 X 881 + 307) = 
 39792.92. Deducting the heat radiated from the cylinder 
 we have 39792.92 X .99 = 39395 B. t. u. per horse power 
 left to do work. The B. t. u. absorbed in mechanical work 
 (useful work + friction) in the cylinder per horse power 
 hour is (33000 X 60) -H 778 = 2545 B. <t. u. Subtracting 
 this work loss we have 39395 2545 = 36850 B. t. u. given 
 up to the exhaust per horse power hour. Comparing this 
 value with the total heat in the same weight of saturated 
 steam at 2 pounds gage, we have 100 X 36850 -i- (34 X 
 1152.8) = 94 per cent. 
 
 Compound Corliss Engine. Case Two. With the same terms 
 as above let r = 867.4, x = .98, q = 324.4, and W s = 22, 
 then the initial B. t. u. = 22(.98 X 867.4 -=- 324.4) = 25837.9. 
 Less 2 per cent, radiation losses = 25837.9 X .98 = 25321.14 
 B. t. u. The loss absorbed in doing mechanical work in the 
 cylinder per horse power is, as before, 2545 B. t. u. Sub- 
 tracting this we have 25321.14 2545 = 22776.14 B. t. u. 
 given up to the exhaust per horse power hour. Comparing 
 as before with saturated steam at 2 pounds gage, we have 
 
 100 X 22776.14 -f- (22 X 1152.8) = 90 per cent. 
 
 Case three. Now suppose superheated steam be used in 
 the first application, all other conditions being the same, 
 the steam having 150 degrees of superheat, what difference 
 will this make in the result? The total heat entering the 
 cylinder now is the total heat of the saturated steam at 
 the initial pressure plus the heat given to it in the super- 
 heater. Let Cp = specific heat of superheated steam and 
 td the degrees of superheat, then the total heat of the 
 superheated steam is 
 
 Total B. t. u. (sup.) = W 8 (xr + q + Cpta) (72) 
 
 This for one horse power of steam (34 pounds), if the 
 specific heat of superheated steam is .54, would be 34 X .99 
 X (1188 + .54 X 150) = 42714.5 B. t. u. and the heat turned 
 into the exhaust will be 42714.5 2545 = 40169.5 B. t. u. 
 Comparing this with the heat in saturated steam at 2 
 pounds gage, we have 100 X 40169.5 -r- (34 X 1152.8) = 102 
 per cent. 
 
198 HEATING AND VENTILATION 
 
 Case four. Pump exhausts are sometimes led into the 
 supply and used for heating- purposes along with the engine 
 exhausts. If such conditions he found, what is the heating 
 value of such steam? Assume the live steam to enter the 
 steam cylinder of the pump under the same pressure and 
 quality as recorded for the high speed engine. The steam 
 is cut off at about % of the stroke and expands to the end 
 of the stroke. With this small expansion the absolute 
 pressure at the end of the stroke would be approximately 
 % X 112 = 98 pounds, and, if enough heat is absorbed from 
 the cylinder wall to bring the steam up to saturation at 
 the release pressure, we will have a total heat above 32 
 degrees, in the exhaust steam per pound of steam at 98 
 pounds absolute, of 1185.6 B. t. u. Comparing this with a 
 pound of saturated steam at 2 pounds gage, we have 
 100 X 1185.6 -=- 1152.8 = 103 per cent. Under the con- 
 ditions such as here stated with a high release pressure, 
 a small expansion of steam in the cylinder and dry steam 
 at the end of the stroke, it is possible to suddenly drop the 
 pressure from pump release to a low pressure, say 2 pounds 
 gage, and have all the steam brought to a state approach- 
 ing superheat. It is not likely, however, that the steam 
 is dry at the end of the stroke in any pump exhaust, be- 
 cause the heat lost in radiation and in doing work in the 
 slow moving pump would be such as to have a considerable 
 amount of entrained water with the steam, thus lowering 
 the quality of the steam. These above conditions are ex- 
 treme and are not obtained in practice. 
 
 From cases one and two it would appear that the 
 greatest amount of heat that can be expected from engine 
 exhausts, for use in heating systems at or near the pres- 
 sure of the atmosphere, is 90 to 94 per cent, of that of 
 saturated steam at the same pressure. The percentage 
 will, in most cases, drop much below this value. All 
 things considered, exhaust steam having 80 to 85 per oent. of the 
 value of saturated steam at the same pressure is probably the safest 
 rating when calculating the amount of radiation which can be sup- 
 plied by the engines. In many cases no doubt this could be 
 exceeded, but it is always best to take a safe value. On 
 the other hand, when figuring the amount of condenser tube sur- 
 face or reheater tube surface to condense the steam, it would 
 be best to take exhaust steam at 100 per cent, quality, since this 
 would be working toward the side of safety. 
 
DISTRICT HEATING 199 
 
 In plants where the exhaust steam is used for heating 
 purposes and where the amount supplied by direct acting 
 steam pumps is large compared with that supplied by the 
 power units, it is possible to have the quality of the ex- 
 hausts anywhere between 800 and 1000 B. t. u. per pound 
 of exhaust. It should be understood that saturated steam 
 at any stated pressure always has the same number of 
 B. t. u. in it, no matter whether it is taken directly from 
 the boiler, or from the engine exhaust. A pound of the 
 mixture of steam and entrained water, taken from engine 
 exhausts, should not be considered as a pound of steam. 
 If we are speaking of a pound of exhaust steam without 
 the entrained water as compared with a pound of saturated 
 steam at the same pressure, they are the same, but a pound 
 of engine exhaust or mixture is a different thing. 
 
200 
 
 HEATING AND VENTILATION 
 
 HOT WATER SYSTEMS. 
 
 140. Two General Classifications of hot water heating, 
 and a number of modifications of these, may be found in 
 current work. The power plant apparatus for each of 
 these systems is all very much the same, but the outside 
 work in the two general systems is entirely different. The 
 first, known as the one-pipe complete circuit system, is shown 
 
 POWER HOUSE. 
 
 Fig. 95. 
 
 in Fig. 95. It will be noticed that the water leaves the 
 power plant and makes a complc-ta circuit of the district, 
 as A, B, C, D, E, F, O, through a single pipe of uniform 
 diameter. From this main is taken branch mains and 
 leads to the various houses, as a, 6, c and d, e, each one re- 
 turning to the principal main after having made its own 
 minor circuit. The other is known as the two-pipe high 
 pressure system, in which two main pipes of like diameter 
 laid side by side in the same conduit, radiate from the 
 power plant to the farthest point on the line reducing 
 in size at certain points to suit the capacity of that part 
 of the district served. This system is represented by Fig. 
 96. In the one-pipe system the circulation in the various 
 
DISTRICT HEATING 
 
 201 
 
 residences is maintained, in part, by what is known as the 
 shunt system, and in part, by the natural gravity cir- 
 culation. The circulation in the two-pipe system is main- 
 tained by a high differential pressure between the main 
 and the return at the same point of the conduit. The force 
 producing movement of the water in the shunt system is, 
 therefore, very much less than in the two-pipe system. As a 
 consequence, the one-pipe system has a lower velocity of the 
 water in the houses and larger service pipes than the two- 
 pipe system. 
 
 ~ r =\ 
 
 POWER Hou&t 
 
 Fig. 96. 
 
 In many cases it is desired to connect central heating 
 mains to the low pressure hot water systems in private 
 plants. Such connections may easily be made with either 
 one of the two systems by installing some minor pieces 
 of apparatus for controlling the supply. 
 
 141. Amount of Water Needed Per Hour as a Heating 
 Medium: All calculations must necessarily begin with the 
 heat lost at the residence. Referring to the Standard room 
 mentioned in Art. 78, we find the heat loss to be 14000 B. t. u. 
 per hour, requiring 84 square feet of hot water heating sur- 
 face to heat the room. Let the circulating water have the 
 following temperatures: leaving the power plant 180*, enter- 
 ing the radiator 177, leaving the radiator 157, and entering 
 
202 HEATING AND VENTILATION 
 
 the power plant 155. According to these figures, which may 
 be considered fair average values, the water gives off to the 
 radiator 20 B. t. u. per pound or 166.6 B. t. u. per gallon, thus 
 requiring 14000 -r- 166.6 84 gallons of water per hour to 
 maintain the room at a temperature of 70. From this a 
 fairly safe estimate may be given, i. e., each square foot of hot 
 water radiation in the city will require approximately one gallon of 
 water per hour. It is very certain that some plants are de- 
 signed to supply less than this amount, but in such cases it 
 requires a higher temperature of the circulating water and 
 allows little chance for future expansion of the plant. A 
 drop of 20 degrees, i. e., 20 B. t. u. heat loss per pound of water 
 passing through the radiator, is probably a maximum and in- 
 dicates the minimum amount of water that should be circu- 
 lated. In practice, this heat loss would probably be nearer 
 15 B. t. u. per pound, and consequently would necessitate the 
 use of somewhat more than one gallon of water per square 
 foot of heating surface per hour. All things considered, the 
 above italicised statement will satisfy every condition. Hav- 
 ing the total number of square feet of radiation in the dis- 
 trict, the total amount of water circulated through the mains 
 per hour can be obtained, after which the size of the pumps 
 in the power plant may be estimated. 
 
 142. Radiation in the District: The amount of radia- 
 tion that may be installed in the district is problematical. In 
 an average residence or business district the following fig- 
 ures may easily be realized: business square, 9000 square feet; 
 residence square, 4500 square feet. In certain locations these fig- 
 ures may be exceeded and in others they may be reduced. 
 Where the needs of the district are thoroughly understood a 
 miore careful estimate can easily be made. It is always well 
 to make the first estimate a safe one and any possible in- 
 crease above this figure could be taken care of as in Art. 
 141. Referring to Fig. 92, an estimate of the amount of 
 radiation that may be expected in this typical case, if we 
 assume ten business squares and twenty-one residence 
 squares, is 184500 square feet. This will call for the circu- 
 lation of 184500 gallons of water per hour. 
 
 143. Future Increase in Radiation: From the tempera- 
 tures given in Art. 141, it will be seen that each pound of 
 water takes on 25 B. t. u. at the power plant and that there 
 
DISTRICT HEATING 203 
 
 is a possible increase of 212 180 = 32 B. t. u. per pound that 
 may be given to it, thus increasing the capacity of the system 
 approximately 125 per cent. It would not be safe to count 
 on such an increase in the average plant because of a defec- 
 tive layout in the piping system or because of a low ef- 
 ficiency in some of the pumps or other apparatus in the 
 plant. If, however, a plant is installed according to the above 
 figures, the capacity may be quite materially increased by 
 increasing the temperature of the outgoing water at the 
 plant to 212. 
 
 144. The Pressure of the Water In the Mains: The ele- 
 vation above the plant at which a central station can supply 
 radiation is limited. Water at 180 will weigh 60.55 pounds 
 per cubic foot, and the pressure caused by an elevation of 1 
 foot is .42 pound per square inch. From this the static pres- 
 sure at the power plant, due to a hydraulic head of 100 feet, 
 is 42 pounds per square inch. This value should not be ex- 
 ceeded, and generally, because of the influence it has on the 
 machines and pipes toward producing leaks or complete 
 ruptures, a less head than this is desirable. A static pres- 
 sure of 42 pounds may be expected to produce, in a well de- 
 signed plant, an outflow pressure of 65 to 75 pounds per 
 square inch and a return pressure of 15 to 20 pounds per 
 square inch, when working under fairly heavy service. In 
 any case where the mains are too small to supply the radia- 
 tion in the system properly, we may expect the value given 
 for the outflow to increase and that for the return to de- 
 crease. A safe set of conditions to follow is: head, in feet, 
 60; static pressure, in pounds per square inch, 25; outgoing 
 pressure at the pumps, in pounds per square inch, 60; return 
 pressure at the pumps, in pounds per square inch, 15. 
 This differential pressure of 45 pounds is caused by the 
 friction losses in the piping system, pumps and heaters. 
 Long pipe systems, as these are called, have much greater 
 friction losses in the long runs of piping than in the ells, 
 tees, valves, etc., hence, the friction head of the pipes is all 
 that is usually considered. Where the minor losses are 
 thought to be large, they may be accounted for by adding 
 to the pipe loss a certain percentage of itself. 
 
204 HEATING AND VENTILATION 
 
 The maximum pressure in the system is due to two 
 causes; first, the static head, and second, the frictional re- 
 sistances. The first is easily estimated when the static 
 head is known. To obtain the second, formula 73 is rec- 
 ommended. See Merriman's "A Treatise on Hydraulics," 
 Arts. 86 and 100, and Church's "Mechanics of Engineering", 
 Art. 519. 
 
 (frl V s 
 
 n f = x- (73) 
 
 d 2g 
 
 where lif = feet of head lost in friction, $ = friction factor 
 (synonomous with coefficient of friction. For clean cast 
 iron pipes with a velocity of 5 to 6 feet per second this 
 has been found to vary from .024 to .019, for diameters 
 between 3 and 15 inches respectively. .02 is suggested as 
 a safe average value to use), I = length of pipe in feet, 
 v = velocity of the water in feet per second, d = diameter 
 of pipe in feet and 2g = 64.4. 
 
 APPLICATION. In Fig. 96, let it be desired to find the 
 differential pressure at the pumps due to the friction losses 
 in the line A, B, C, D, E. The lengths of the various parts 
 are: power plant to A, 200 feet; A to B, 500 feet; B to C, 
 1500 feet; C to D, 1500 feet, and D to E, 500 feet. 
 Assume, for illustration, that the total radiation in square 
 feet beyond each of these points is, power plant, 125000: 
 A, 85000; B, 50000; C, 28000 and D, 12000. This requires 
 125000, 85000, 50000, 28000 and 12000 gallons of water per 
 hour, or 4.74, 3.27, 1.75, 1 and .44 cubic feet of water per 
 second, respectively, passing these points. Now, if the 
 velocities be roughly taken at 6 and 5 feet per second, 
 (pipes near the power plant may be g-iven somewhat higher 
 velocities), the pipes will be 12, 10, 8, 6 and 4 inches diam- 
 eter. In applying the formula to one part of the line we 
 show the method employed for each. Take that part from 
 the power plant to A. With v = 6 
 
 .02 X 200 X 36 
 
 Ji f = =2.2 feet 
 
 64.4 X 1 
 
 It should be noted here that formula 73 refers to pipes 
 where all the water that enters at one end passes out the other. 
 This is not true in heating mains where a part of the 
 
DISTRICT HEATING 
 
 205 
 
 water is drawn off at intermediate points. On the other 
 hand, Merriman, Art 99, explains that a water service main, 
 where the water is all taken off from intermediate tappings and 
 where tne velocity at the far end is zero, causes only one-third 
 of the friction given by the above formula. The case under 
 consideration falls somewhere between these two extremes, 
 the part next the power plant approaching the former and 
 the last part of the line exactly meeting the conditions of 
 the latter. Assuming the mean of these two conditions, 
 which is probably very close to the actual, gives two-thirds 
 of that found by the formula. Now since this is a double 
 main system, i. e., main and return of the same size, the 
 friction head for the two lines becomes 2.94 feet, from 
 the power plant to A. In a similar way the other parts 
 may be tried and the results from the entire line assembled 
 in convenient form as in Table XXVII. 
 
 TABLE XXVII. 
 
 
 P. P. 
 to A. 
 
 A toB 
 
 B to C 
 
 C to D 
 
 Dto E 
 
 .Distance between points 
 Radiation supplied 
 
 200 
 125000 
 
 500 
 85000 
 
 1500 
 50000 
 
 1500 
 28000 
 
 500 
 12000 
 
 Volume of water passing point 
 in cu. ft. per sec. 
 
 4-74 
 
 8 27 
 
 1-75 
 
 1. 
 
 44 
 
 Velocity f. p, s. 
 
 6 
 
 Q 
 
 5 
 
 5 
 
 5 
 
 Area of pipe sq. ft. 
 
 .79 
 
 545 
 
 .85 
 
 .20 
 
 .087 
 
 Diam. of pipe in ft. 
 
 1 
 
 .83 
 
 .66 
 
 5 
 
 .38 
 
 hf by (78) for flow main.. . 
 
 2.2 
 
 6.7 
 
 17.4 
 
 23 8 
 
 11.7 
 
 7.V (taking value) 
 
 1.47 
 
 4.47 
 
 11.6 
 
 15.5 
 
 7.8 
 
 hf ( val. flow and return) 
 
 2.94 
 
 8-94 
 
 28-2 
 
 81.0 
 
 15.6 
 
 From the last line of the table we obtain the total 
 friction head for both mains, not including ells, tees, valves, 
 etc., to be 81.6 feet. This is equivalent to 34.3 pounds per 
 square inch. Now if we allow about 20 per cent, of all the 
 line losses to cover the minor losses we have approximately 
 40 pounds differential pressure, which is a reasonable 
 value. 
 
 145. Velocity of the Water in the Mains and the Di- 
 ameter of the Mains: The district is first chosen and the 
 layout of the conduit system is made. This is done inde- 
 pendently of the sizes of the pipes. When this layout Is 
 finally completed, the pipe sizes are roughly calculated for 
 
206 HEATING AND VENTILATION 
 
 all the important points in the system a.nd are tabulated 
 in connection with the friction losses for these parts, as 
 in Art. 144. When this is d/>ne, formula 74, which is rec- 
 ommended to be used in connection with (73), may be 
 applied and the theoretical diameters found. (The approx- 
 imate diameters and the friction heads need not be calcu- 
 lated in (73) for use in (74) providing some estimate may 
 be made for the value hf, for the various lengths of pipe. 
 If desired, hf may be assumed without any reference to the 
 diameter, but this is a rather tedious process. For good 
 discussion of this point see Church's Hydraulic Motors, 
 Art. 121.) 
 
 $IQ 
 d = .479/% X - (74) 
 
 where d, hf, and I are the .same as in (73), and Q = cubic 
 feet of water passing through the pipe per second. This 
 formula differs from those given in the references stated, 
 in that the term % is inserted as a mean value between 
 the two extreme conditions, as stated in Art. 144. 
 
 APPLICATION. Let it be desired to find the diameter for 
 the single main between the power plant and A, Art. 144, 
 with h f = 1.47 
 
 2 X .02 X 200 X (4.74) 2 V 5 
 
 d .479 ( - : ---- \ = 1 ft. = 12 in. 
 ^ 3 X 1.47 ' 
 
 Applying to the entire line with hf as given in next to last 
 line of Table XXVII, gives power plant to A, d = 12 inches; 
 A to B, d = 10 inches; B to C, d = 8 inches; C to D, d = 6 
 inches; and D to E, d = 4 inches. 
 
 In some cases, when close estimating is not required, 
 it is satisfactory to assume a velocity of the water and find 
 the diameter without considering the friction loss. In 
 many cases, however, this would soon prove a positive loss 
 to the Company. With a .low velocity, the pipe would be 
 large, the first cost would be large and the operating cost 
 would be low. On the other hand, if the velocity were 
 high, the pipe would be small, the first cost would be 
 small and the operating cost and depreciation would be 
 large. As an illustration of how the friction head in- 
 creases in a pipe of this kind with increased velocity, 
 
DISTRICT HEATING . 207 
 
 refer to the run of mains between B and C. Assuming a 
 velocity of 10 feet per* second, which in this case would be 
 very high, the friction head, hf, for the single main, be- 
 comes 62 and the theoretical diameter is 5.5, say 6 inches. 
 The friction head, as will be seen, is 5.4 times the cor- 
 responding value when the velocity was 5 feet per second. 
 Since the pump must work continually against this head, 
 it would incur a financial loss that would soon exceed the 
 extra cost of installing larger pipes. It is found in plants 
 that are in first class operation that the velocities range 
 from 5 to 7 feet per second. 
 
 The calculations in Arts. 144 and 145 are very much 
 simplified by the use of the chart shown in the Appendix. 
 In planning a system of this kind, find the friction head 
 on the pumps and the diameters of the pipes for various 
 velocities, say 4, 6, 8 and 10 feet per second. Estimate the 
 probable first cost and the depreciation of the conduit 
 system for each velocity, and balance these figures with 
 the operating cost for a period of, say five years, to see 
 which is the most economical velocity to use in figuring 
 the system. 
 
 146. Service Connections are usually installed from 30 
 to 36 inches below the surface of the ground, and are in- 
 sulated in some form of box conduit which compares favor- 
 ably with that of the main conduit. Service branches are 
 li/4, IVa and 2 inch wrought iron pipe. These are usually 
 carried to the building from the conduit at the expense 
 of the customer. Such branch conduits are not drained 
 by tile drains. 
 
 147. Total Steam Available and B. t. u. Liberated per 
 Hour for Heating the Circulating Water: The amount of 
 steam available for heating the circulating water is that 
 given off by the generating units, plus that from the cir- 
 culating pumps, plus that from the city water supply pumps 
 if there be any, plus that from the auxiliary steaming units 
 in the plant, i. e., small pumps, engines, etc. In the typical 
 application this amounts to 23100 + 12720 + 8680 = 44500 
 pounds per hour. 
 
 This steam, of course, is not equal to good dry steam in 
 heating value because of the work it has done in the engine 
 
208 HEATING AND VENTILATION 
 
 and pump cylinders, but a good estimate of its value may 
 be approximated. In addition to the terms used in for- 
 mula 71, let q' heat in the returning condensation per 
 pound; then the heat available for heating- purposes per 
 pound of exhaust steam is 
 
 B. t. u. = xr + q q' (75) 
 
 It is probably safe to consider the quality of the steam as 
 85 per cent, of that of good dry steam at the same pressure. 
 Since the pressure of the exhaust from a non condensing 
 engine, as it enters the heater, is near that of the atmosphere, 
 and since the returning condensation is at a temperature of 
 about 180, the total amount of heat given off from a pound 
 of exhaust steam to the circulating water is 
 
 B. t. u. = .85 X 969.7 + 180.3 (180.54 32) = 856, say 850. 
 
 If Wt be the pounds of exhaust steam available, the total 
 number of B. t. u. given off from the exhaust steam per hour is 
 
 Total B. t. u. = 850 W a (76) 
 
 Applying this to the typical power plant gives 850 X 
 44500 37825000 B. t. u. per hour. This amount is probably 
 a maximum under the conditions of lighting units as stated, 
 and would be true for only 5 hours out of 24. At other times 
 the exhaust steam drops off from the lighting units and this 
 deficiency must be made good by heating the circulating 
 water directly from the coal, by passing the water through 
 heating boilers or by passing it through economizers where 
 it is heated by the waste heat from the stack gases. 
 
 148. Amount of Hot Water Radiation in the District 
 that can be Supplied by One Pound of Exhaust Steam on a 
 Zero Day: In Art. 141, each pound of water takes on 25 
 B. t. u. in passing through the reheaters at the power plant, 
 and gives off at least 20 B. t. u. in passing through the 
 radiator. The number of pounds of water heated per pound 
 of steam per hour is, W v = (Total B. t. u. available per 
 pound of exhaust steam per hour) -~ 25, and the total radi- 
 ation that can be supplied is 
 
 Total B.t.u. available per Ib. of exhaust steam per hr. 
 
 R W (77) 
 
 8.33 X 25 
 
DISTRICT HEATING 209 
 
 which for average practice reduces to 
 
 850 
 
 R w = =: 4 square feet approx. (78) 
 
 208 
 
 Applying- formula 77 for the five hour period when the 
 exhaust steam is maximum gives R w 37825000 -^ 208 = 
 181851 square feet. It is not safe to figure on the peak load 
 conditions. It is better to assume that for half the time, 
 35000 pounds of steam are available and will heat 35000 
 X 4 = 140000 square feet of radiation. 
 
 149. The Amount of Circulating; Water Passe*! through 
 the Heater Necessary to Condense One Pound of Exhaust 
 Steam is 
 
 Total B.t.u. available per Ib. of exhaust steam per hr. 
 
 Wv, (79) 
 
 25 
 
 With the value given above for the exhaust steam this 
 becomes, for 100 and 85 per cent, respectively, 
 
 1000 
 
 W w = = 40 pounds (80) 
 
 25 
 
 850 
 
 W w 34 pounds (81) 
 
 25 
 
 150. Amount of Hot Water Radiation in the District 
 tlisit can be Heated by One Horse Power of Exhaust Steara 
 from a Non Condensing Engine on a Zero Day: 
 
 R w = 4 X (pounds of steam per H. P. hour) (82) 
 
 This reduces for the various types of engines, as follows: 
 
 Simple high speed 4 X 34 = 136 square feet. 
 
 " medium " 4 X 30 = 120 " " 
 
 Corliss 4 X 26 = 104 
 
 Compound high " 4X26 = 104 
 
 " medium " 4 X 25 = 100 
 
 " Corliss 4 X 22 = 88 
 
 151. Amount of Radiation that can be Supplied by Ex- 
 haust Steam in Formulas 77 and 78 at any other Temper- 
 ature of the "Water, fw, than that stated, with the Room 
 
210 
 
 HEATING AND VENTILATION 
 
 Temperature, t', remaining the same: The amount of heat 
 passing through one square foot of the radiator to the room 
 is in proportion to t w t'. In formulas 77 and 78, t w V 
 100. Now if tw be increased x degrees, so that tw t f = 
 (100 + x), then each square foot of radiation in the building 
 
 100 + x 
 will give off 
 
 times more heat than before and 
 
 100 
 
 each pound of exhaust steam will supply only 
 
 4 X 100 
 
 square feet 
 
 (83) 
 
 100 + x 
 
 This for an increase of 30 degrees, which is probably a max- 
 imum, is 
 
 4 
 
 R w = = 3 square feet (84) 
 
 1.3 
 
 Compared with (78), formula 83 shows, with a high tem- 
 perature of the water entering the radiator, that less radi- 
 ation is necessary to heat any one room and that each 
 square foot of surface becomes more nearly the value of an 
 equal amount of steam heating surface. Calculations for 
 radiation, however, are seldom made from high temper- 
 atures of the water,' and this article should be considered 
 an exceptional case. 
 
 152. Exhaust Steam Condenser (Reheater), for Reheat- 
 ing the Circulating Water: In the layout of any plant 
 the reheaters should be located close to the circulating 
 pumps and on the high pressure side. They are usually of 
 the surface condenser type, Fig. 97, and may or may not be 
 installed in duplicate. Of the two types shown in the fig- 
 ure, the water tube type is probably the more common. The 
 same principles hold for each in design. In ordinary heaters 
 for feed water service, wrought iron tubes of iy 2 to 2 inches 
 
 WATET? TUBE TVPt 
 
 WATEP 
 
 STEAM TUBLTVPE 
 
 Fig. 97. 
 
DISTRICT HEATING 211 
 
 diameter are generally used, but for condenser work and 
 where a rapid heat transmission is desired, brass or copper 
 tubes are used, having diameters of % to 1 inch. In heating 
 the circulating water for district service, the reheater is 
 doing very much the same work as if used on the condens- 
 ing system for engines or turbines. The chief difference is in 
 the pressures carried on the steam side, the reheater con- 
 densing the steam near atmospheric pressure and the con- 
 denser carrying about .9 of a perfect vacuum. In either case 
 it should be piped on the water side for water inlet and out- 
 let, while the steam side should be connected to the exhaust 
 line from the engines and pumps, and should have proper 
 drip connections to draw the water of condensation off to a 
 condenser pump. This condenser pump usually delivers the 
 water of condensation to a storage tank for use as boiler 
 feed, or for use in making up the supply in the heating sys- 
 tem. 
 
 In determining the details of the condenser the following 
 important points should be investigated: the amount of 
 heating surface in the tubes, the size of the water inlet and 
 outlet, the size of the pipe for the steam connection, the size 
 of the pipe for the water of condensation and the length 
 and cross section of the heater. 
 
 153. Amount of Heating Surface in the Reheater Tubes: 
 
 The general formula for calculating the heating surface in 
 the tubes of a reheater (assuming all heating surface on 
 tubes only), is 
 
 Total B. t. u. given up by the exhaust steam per hr 
 
 R t = ( 85 ) 
 
 K (Temp. diff. between inside and outside of tubes) 
 
 The maximum heat given off from one pound of exhaust 
 steam in condensing at atmospheric pressure is 1000 B. t. u., 
 the average temperature difference is approximately 47 
 degrees, and K may be taken 427 B. t. u. per degree dif- 
 ference per hour. In determining K, it is not an easy mat- 
 ter to obtain a value that will be true for average practice. 
 Carpenter's H. & V. B. Art. 47 quotes the above figure for 
 tests upon clean tubes, and volumes of water less than 
 1000 pounds per square foot of heating surface per hour. 
 It is found, however, that the average heater or condenser 
 
212 HEATING AND VENTILATION 
 
 tube with its lime and mud deposit will reduce the efficiency 
 as low as 40 to 50 per cent, of the maximum transmission. 
 Assume this value to be 45 per cent.; then if W a is the 
 number of pounds of available exhaust steam, formula 85 
 becomes 
 
 1000 TF, 1000 W, 1000 W, W, 
 Rt = _ (86) 
 
 K(t, tw) 427 X .45 X 47 9031 9.1 
 
 In "Steam Engine Design," by Whitham, page 283, the 
 following formula is given for surface condensers used on 
 shipboard: 
 
 W L 
 
 S = 
 
 CK (!,. 
 
 where = tube surface, W = total pounds of exhaust steam 
 to be condensed per hour, L = latent heat of saturated steam 
 at a temperature T it K theoretical transmission of B. t. u. 
 per hour through one square foot of surface per degree dif- 
 ference of temperature = 556.8 for brass, c = efficiency of 
 the condensing surface = .323 (quoted from Isherwood), TI = 
 temperature of saturated steam in the condensers, and * 
 average temperature of the circulating water. 
 "With L = 969.7, c = .323, K = 556.8 and TI t 47, we 
 may state the formula in terms of our text as 
 
 969.7 W* W* 
 
 Rt = = = (87) 
 
 .323 X 556.8 X 47 8446 8.7 
 
 In Sutcliffe "Steam Power and Mill Work," page 512, the 
 author states that condenser tubes in good condition and set 
 in the ordinary way have a condensing power equivalent to 
 13000 B. t. u. per square foot per hour, when the condensing 
 water is supplied at 60 degrees and rises to 95 degrees at dis- 
 charge, although the author gives his opinion that a trans- 
 mission of 10000 B. t. u. per square foot per hour is all that 
 should be expected. This checks closely with formula 86, 
 which gives the rate of transmission 9031 B. t. u. per square 
 foot per hour. 
 
 The following empirical formula for the amount of heat- 
 ing surface in a heater is sometimes used: 
 
 R t = .0944 W s (88) 
 
 Where the terms are the same as before. 
 
DISTRICT HEATING 213 
 
 APPLICATION. Let the total amount of exhaust steam avail- 
 able for heating the circulating- water be 35000 pounds per 
 hour, the pressure of the steam in the condenser be atmos- 
 pheric and the water of condensation be returned at 180; 
 also, let the circulating water enter at 155 and be heated to 
 180. These values are good average conditions. The assump- 
 tion that the pressure within the condenser is atmospheric 
 might not be fulfilled in every case, but can be approached 
 very closely. From these assumptions find the square feet 
 of surface in the tubes. 
 
 35000 
 Formula 86, R t = - = 3846 sq. ft. 
 
 9.1 
 
 35000 
 Formula 87, R t = - = 4023 sq. ft. 
 
 8.7 
 Formula 88, R t = 35000 X .0944 = 3304 sq ft. 
 
 1000 X 35000 
 
 Satellite R t = -- = 3500 sq. ft. 
 10000 
 
 If 3846 square feet be the accepted value it will call for 
 three heaters having 1282 square feet of tube surface each. 
 
 154. Amount of Reheater Tube Surface per Engine Horse 
 Power: Let tc s be the pounds of steam used per I. H. P. of 
 the engine; then from formula 86 
 
 Rt (per /. H. P.) = - (89) 
 
 9.1 
 
 This reduces for the various types of engines as follows: 
 
 Simple high speed 34 -=- 9.1 = 3.74 square feet 
 
 " medium " 30 -J- 9.1 = 3.30 
 
 " Corliss 26 -T- 9.1 = 2.86 
 
 Compound high " 26 ^ 9.1 = 2.86 
 
 " medium " 25 -j- 9.1 = 2.75 
 
 " Corliss 22 -H 9. 1=2. 42 
 
 155. Amount of Hot Water Radiation in the District 
 that can he Supplied by One Square Foot of Reheater Tube 
 Surface: If the transmission through one square foot of 
 
214 HEATING AND VENTILATION 
 
 tube surface be K (t s w ) = 9031 B. t. u. per hour and 
 the amount of heat needed per square foot of radiation per 
 
 hour = 8.33 X 25 = 208, as given in formula 77, then 
 
 9031 
 R w (per sq. ft. of tube surface) = = 43 . 4 sq. ft. (90) 
 
 208 
 
 156. Some Important Reheater Details: Inlet and Outlet 
 Pipes: Having three heaters in the plant, it seems rea- 
 sonable that each heater should be prepared for at least one- 
 third of the water credited to the exhaust steam. From 
 Art. 148 this is 140000 -f- 3 = 46667 gallons = 10800000 cubic 
 inches per hour. The velocity of the water entering and 
 leaving the heater may vary a great deal, but good values 
 for calculations may be taken between 5 and 7 feet per 
 second. Assuming the first value given, we have the area 
 of the pipe = 10800000 -f- (5 X 12 X 3600) = 50 square inches, 
 and the diameter 8 inches. 
 
 The Size of the Reheater Shell. Concerning the velocity 
 of the water in the reheater itself, there may be dif- 
 ferences of opinion; 100 feet per minute will be a good value 
 to use unless this value makes the length of the tube too 
 great for its diameter. If this is the case the tube will bend 
 from expansion and from its own weight. At this velocity 
 the free cross sectional area of the tubes, assuming the water 
 to pass through the tubes as in Fig. 97, would be 150 
 square inches. If the tubes be taken % inch outside diam- 
 eter, with a thickness of 17 B. W. G., and arranged as usual 
 in such work, it will require about 475 tubes and a shell 
 diameter of approximately 30 inches. If the inner surface of 
 the tube be taken as a measurement of the heating surface 
 and the total surface be 1282 square feet, the length of the 
 reheater tubes would be approximately 16 feet. 
 
 The ratio of the length of the tube to the diameter is, 
 in this case, 256, about twice as much as the maximum ratio 
 used by some manufacturers. It would be better therefore 
 to increase the number rf tubes and decrease the length. 
 With a velocity of the water at 50 feet per minute, the 
 values will be approximately as follows; free cross sec- 
 tional area of the tubes, 300 square inches; number of tubes, 
 950; diameter of shell, 40 inches; length of tubes, 8 feet. 
 These values check fairly well and could be used. 
 
DISTRICT HEATING 215 
 
 The Size of the Exhaust Steam Connection. To calculate this, 
 use the formula 
 
 144 g, 
 - (91) 
 
 where <?. = volume of steam in cubic feet per minute, V 
 velocity in feet per minute, and A area of pipe in square 
 inches. When applied to the reheater using 35000 pounds 
 of steam per hour, at 26 cubic feet per pound and at a veloc- 
 ity through the exhaust pipe of 6000 feet per minute, it gives 
 144 X 35000 X 26 
 
 A = = 360sq. in. = 22 in. dia. 
 
 60 X 6000 
 Try also, from Carpenter's H. & V. B., page 284. 
 
 .23 (92) 
 
 Allowing 30 pounds of steam per H. P. hour for non condens- 
 ing engines we have 35000 -r- 30 = 1166 horse power; then 
 applying the above we obtain d = 16 inches. Comparing 
 the two formulas, 91 and 92, the first will probably admit of a 
 more general application. The velocity 6000 for exhaust steam 
 may be increased to 8000 for very large pipes and should be 
 reduced to 4000 for small pipes. In the above applications 
 a 20-inch pipe will suffice. 
 
 The Return Pipe for Condensation. The diameter of the 
 pipe leading to the condenser pump will naturally be 
 taken from the catalog size of the pump installed. This 
 pump would be selected from capacities as guaranteed by 
 the respective manufacturers and should easily be capable of 
 handling the amount of water that is condensed per hour. 
 
 The Value of a High Pressure Steam Connection. If desired, 
 the reheater may also be provided with a high pres- 
 sure steam connection, to be used when the exhaust steam 
 is not sufficient. This steam is then used through a pres- 
 sure-reducing valve which admits the steam at pressures 
 varying from atmospheric to 5 pounds gage. There is some 
 question concerning the advisability of doing this. Some 
 prefer to install a high pressure steam heater, as in Art. 157, 
 to be used independently of the exhaust steam heaters. This 
 removes all possibility of having excessive back pressure 
 on the engine piston, as is sometimes the case where high 
 pressure steam is admitted with the exhaust steam. 
 
216 
 
 HEATING AND VENTILATION 
 
 It has been the experience of some who have operated 
 such plants that where more heat is needed than can be 
 supplied by the exhaust steam, it is better to resort to heat- 
 ing boilers and economizers, than to use high pressure steam 
 for heating. 
 
 157. High Pressure Steam Heater: When this heater is 
 used it is located above the boiler so that all the condensa- 
 tion freely drains back to the boilers by gravity as in Fig. 
 98. In calculating the tube surface, use formula 85 with 
 the full value of the steam and the steam temperatures 
 changed to suit the increased pressure. Such a heater as 
 this gives good results. 
 
 Fig. 98. 
 
 158. Circulating Pumps: Two types of pumps are in 
 general use: centrifugal and reciprocating. Each type is 
 somewhat limited in its operation. The centrifugal pump 
 has difficulty in operating against high heads and the recip- 
 
DISTRICT HEATING 217 
 
 rocating pump is very noisy when running at a high piston 
 speed. Since each type is in successful operation in many 
 plants, no comparisons will be made between them further 
 than to say that the former, being operated by a steam en- 
 gine, may be run more economically than the latter because 
 of the possibilities of using the steam expansively. It will 
 be noted, however, that this same steam is to be used in the 
 exhaust steam heaters for warming the circulating water 
 and hence there would be little, if any, direct loss from this 
 source in the use of the reciprocating pump. 
 
 Having given the maximum amount of water to be 
 circulated per hour, consult trade catalogs and select the 
 number of pumps and the size of each pump to be installed. 
 The sizes of the pumps can easily be determined when the 
 number of them has been decided upon. This latter point 
 is one upon which a difference of opinion will probably be 
 found. No exact rule can be applied. In a plant of, say 
 not more than 150000 square feet of radiation (150000 gal- 
 lons of water per hour, or 3 million gallons for twenty-four 
 hours), some designers would put in three pumps, each 
 having 1.5 million gallons capacity; in which case one 
 pump could be cut out for repairs and the other two would 
 be able to care for the service temporarily. Other designers 
 would use four pumps at about one million gallons each. 
 The fewer the pumps installed, in any case, the greater 
 should be the capacity of each. The following values will 
 be found fairly satisfactory: 
 
 1 Pump. Cap. = (1 to 1.25) times max. requirem't of system 
 
 2 Pumps. " (each) = .75 " " " " " 
 
 3 Pumps. " " = .5 " " " " " 
 
 4 Pumps. " " = .3 " " " " " 
 
 Having given the capacity of each pump in gallons of 
 water per minute, the size, the horse power and the steam 
 consumption of each pump can be calculated. In obtaining 
 the size of the pump it will be necessary to know the speed, 
 V, of the piston in feet per minute, the strokes, N, per minute 
 and the per cent, of slip, s (100 per cent. 8, where S = hy- 
 draulic efficiency). The speed varies between 100, for small 
 pumps, and 75, for large pumps. The strokes vary between 
 200, for small pumps, and 40, for large pumps, and the slip 
 varies between 5 and 40 per cent., depending upon the fit of 
 
218 HEATING AND VENTILATION 
 
 the piston and the valves. In pumps that have been in serv- 
 ice for some time the slip will probably average 20 per cent. 
 The cross sectional area of the water cylinder in square 
 inches is 
 
 cubic inches pumped per minute 
 
 W. C. A. = (93) 
 
 8 X V X 12 
 
 from which we may obtain the diameter of the water cylinder. 
 The steam cylinder area is usually figured as a certain 
 ratio to that of the water cylinder area; as, 
 
 8. C. A. = (1.5 to 2.5) X W. C. A. (94) 
 
 from which we may obtain the diameter of the steam cylin- 
 der. 
 
 The length of the stroke, L, in incnes, will be obtained 
 from the speed and the number of strokes such that, 
 
 12 V 
 * = _ (.6) 
 
 All direct acting steam pumps are designated by diam- 
 eter of steam cylinder X diameter of water cylinder X length 
 of stroke; as, 
 
 14" X 12" X 18" 
 
 Duplex pumps have twice the capacity of single pumps 
 having the same sized cylinders. 
 
 To find the indicated horse power, /. H. P., of the pumps, 
 reduce the pressure head, p, in pounds per square inch, to 
 pressure head in feet, h; multiply this by the pounds of 
 water, W, pumped per minute and divide the product by 33000 
 times the mechanical efficiency, E. 
 
 W Ji 
 
 I. H. P. = (96) 
 
 33000 E 
 
 To reduce from pressure head in pounds to pressure 
 head in feet, divide the pressure head in pounds by weight 
 of a column of water one square inch in area and one foot 
 high. The general equation for this is 
 
 144 p 
 h = 
 
 w 
 
 where w = the weight of a cubic foot of water at the given 
 temperature and p differential pressure in pounds per 
 square inch. 
 
DISTRICT HEATING 219 
 
 In pump service of this kind the pressure head, p, against 
 which the pump is acting, is not the result of the static 
 head of water in the system but is due to the inertia of the 
 water and to the resistance to the flow of water through 
 the piping system and the heaters. This frictional resist- 
 ance may be calculated as shown in Art. 144. Read this 
 part of the work over carefully. 
 
 For an illustration of combined pressure head, p, and 
 friction head, Jif, see Art. 161 on boiler feed pumps. Having 
 found the 7. 77. P. of any pump, multiply it by the steam con- 
 sumption per /. H. P. hour and the result will be the steam 
 consumption of the pump. This exhaust steam will be con- 
 sidered a part of the general supply when figuring the size 
 of the exhaust steam heaters in the system. 
 
 The mechanical efficiency, E, of piston pumps depends 
 upon the condition of the valves and upon the speed, and 
 varies from 90 per cent., in new pumps, to 50 per cent., in 
 pumps that are badly worn. A fair average would be 70 
 per cent. 
 
 The steam consumption for reciprocating, simple and 
 duplex non condensing pumps would approximate 100 to 
 200 pounds of steam per 7. 77. P. hour the greater values re- 
 ferring to the slower speeds. 
 
 159. Centrifugal Pumps: Centrifugal pumps are of 
 two classifications, the Volute and the Turbine. The prin- 
 ciples upon which each operate are very similar. The ro- 
 tating impeller, or rotor, with curved blades draws the 
 water in at the center of the pump and delivers it from the 
 circumference. The rotor is enclosed by a cast iron case- 
 ment which is shaped more or less to fit the curvature of 
 the edges of the blades on the rotor. Centrifugal pumps 
 are used where large volumes of water are required at low 
 heads. They are used in city water supply systems, in cen- 
 tral station heating systems, in condenser service, in irri- 
 gation work and in many other places where the pressure 
 head operated against is not excessive. The efficiency of 
 the average centrifugal pump is from 65 to 80 per cent., 
 75 per cent, being nothing uncommon. In places where such 
 pumps are used the head is usually below 75 feet, although 
 some types, when direct connected to high speed motors, 
 are capable of operating against heads of several hundred 
 feet. 
 
220 HEATING AND VENTILATION 
 
 Some of the advantages of centrifugal pumps over hor- 
 izontal reciprocating pumps are: low first cost, simplicity, 
 few moving parts, compactness, uniform flow and pressure 
 of water, freedom from shock, possibilities of having them 
 direct connected to high speed motors and the ability to 
 handle dirty water without injuring the pump. 
 
 One of the advantages of piston pumps over centrifugal 
 pumps is the fact that they are more positive in their op- 
 eration and work against higher heads. 
 
 Centrifugal pumps, when connected to engine and tur- 
 bine drives, benefit by the expansion of the steam and are 
 much more economical than the direct acting piston pump, 
 which takes steam at full pressure for nearly the 'entire 
 stroke. The amount of steam used in the pumps in central 
 station work, however, is not a serious factor, since all of 
 the heat in the steam that is not used in propelling the 
 water through the mains is used in the heaters to increase 
 the temperature of the water. 
 
 The sphere of usefulness of the centrifugal pump in 
 central station heating is increasing. The direct acting 
 piston pump, when operating at fairly high speeds, causes 
 hammering and pounding in the transmission lines, and 
 these noises are sometimes conveyed to the residences and 
 become annoying to the occupants. This feature is not so 
 noticeable in the operation of the centrifugal pump. 
 
 APPLICATION. In Art. 142 assume the capacity of the plant, 
 10 business squares and 21 residence squares, to require 
 184500 gallons of water per hour; the same to be pumped 
 against a pressure head, Art. 144, of 60 15 pounds, by 
 horizontal, direct acting piston pumps. Assume, also the 
 steam consumption of the pumps to be 100 pounds per I. H. P. 
 hour, and the average temperature of the water at the 
 pumps to be (180 + 155) -r- 2 = 167.5 degrees. Apply for- 
 mula 96, where h = calculated total friction head for the 
 longest line in the system (this is designated by lit in Art. 
 144), or where p = total difference between the incoming 
 and the outgoing pressures. With the weight of a cubic 
 foot of water at 167.5 degrees = 60.87 pounds and with 
 p = 45, we have h = 106.5 feet, and the indicated horse power 
 of the pumps, assuming 65 per cent, mechanical efficiency, 
 is 
 
 184500 X 8.33 X 106.5 
 
 I. H. P. =127.2 
 
 33000 X .65 X 60 
 
DISTRICT HEATING 221 
 
 Prom this the steam consumption will probably be 12720 
 pounds per hour. 
 
 If centrifugal pumps were selected, the horse power 
 would be calculated from the same formula, but the steam 
 consumption would probably be 30 to 40 pounds of steam 
 per horse power hour because of the expansive working of 
 the steam. 
 
 160. City Water Supply Pumps: Horizontal, direct act- 
 ing duplex pumps for use on city water supply service are 
 the same as those used to circulate the water in heating 
 systems; hence, the foregoing descriptions apply here. The 
 /. H. P. of the city water supply pumps would be calculated 
 by use of formula 96. If the pumps lifted the water from 
 the wells, as would probably be the case, the suction pres- 
 sure would be negative and would be added to the force 
 pressure. 
 
 APPLICATION. In Art. 186 the pressure in the fresh water 
 mains is 60 pounds and the suction pressure is 10 pounds; 
 therefore, p = 60 ( 10) 70 pounds, and, with the water 
 at 65 degrees, h = 144 X 70 4- 62.5 = 161 feet. These pumps 
 are each rated at 1.5 million gallons in 24 hours, and deliver 
 62500 X 8.33 = 520833 pounds of water per hour, when run- 
 ning at full capacity. Assuming each pump to deliver 75 per 
 cent, of the full requirement of the system, the total amount 
 of water pumped per hour for the city water supply would 
 approximate 520833 -f- .75 = 694444 pounds, and the total 
 average horse power used in pumping the water would be 
 
 694444 X 161 
 
 I. H, P = =86.8 
 
 60 X 33000 X .65 
 
 With 100 pounds of steam per horse power hour, this will 
 amount to 8680 pounds of steam available per hour for use in 
 heating the circulating water. 
 
 161. Boiler Feed Pumps: Horizontal pumps for high 
 pressure boiler feeding are selected in a similar way to the 
 circulating pumps for the city water supply. Such units 
 are called auxiliary steam units and, because the steam re- 
 quired is small, they are sometimes piped to a feed water 
 heater for heating the boiler feed. The velocity of the water 
 through the suction pipe is about 200 feet per minute and 
 
222 HEATING AND VENTILATION 
 
 in the delivery pipe about 300 feet per minute. The piston 
 speed, the strokes per minute and the slip would be very much 
 the same as stated under circulating 1 pumps. Such pumps 
 should have a pumping- capacity about twice as great as the 
 actual boiler requirements and, in small plants where only 
 one pump is needed, the installation should be in duplicate. 
 The sizes of the cylinders and the efficiencies are about as 
 stated for the larger circulating- pumps. 
 
 In determining the horse power of a boiler feed pump, 
 four resistances must be overcome; i. e., pressure head, p, 
 or boiler pressure; suction head, 7t s ; delivery head, ha', and 
 the friction head, hf. The first three values are usually given. 
 The friction head includes the resistances in all piping, 
 ells and valves from the supply to the boiler. The friction 
 in the piping- may be taken from Table 32 or it may be 
 worked out by formula 73. The friction in the ells and 
 valves is more difficult to determine and is usually stated 
 in equivalent length of straight pipe of the same diameter. 
 A rough rule used by some in such cases is as follows: 
 "to the length of the given pipe, add 60 times the nominal 
 diameter of the pipe for each ell, and 90 times the diameter 
 for each globe valve," then find the friction head as stated 
 above. A straight flow gate or water valve could safely be 
 taken as an ell. P or simplicity of calculation, all of the 
 above resistances may be reduced to an equivalent head, 
 such that 
 
 144 p 
 
 + ha + h. + ht (97) 
 
 where w = weight of one cubic foot of water at the suc- 
 tion temperature, w may be obtained from Table 6 
 and hf may be taken from Table 32. The horse power by 
 formula 96 then becomes, if W = pounds of water pumped 
 per minute, 
 
 W X he 
 
 I. H. P. = (98) 
 
 33000 E 
 
 APPLICATION. Let p = 125 pounds gage, to = 62.5, /J d = 8 
 feet, h s = 20 feet, horizontal run of pipe from supply to 
 pump = 20 feet, horizontal run of pipe from pump to boiler 
 = 30 feet; also, let the pump supply 89000 pounds of water 
 per hour to the boiler. This is twice the capacity of the 
 boiler plant. With this amount of water at the usual veloc- 
 
DISTRICT HEATING 223- 
 
 ity it will give a suction pipe of 4.5 inches diameter, and a 
 flow pipe of 4 inches diameter. Let there be two ells and 
 one gate valve on the suction pipe, and three ells, one globe 
 valve and one check valve on the delivery pipe. We then 
 have an equivalent of 107 feet of suction pipe, and 158 feet 
 of delivery pipe. Referring to Table 32, hf is approxi- 
 mately 7 feet, and the total head is 
 
 144 X 125 
 
 he = \- 8 + 20 + 7 = 323 feet. 
 
 62.5 
 In most boiler feed pumps it is considered unnecessary 
 
 to determine lit so carefully. A very satisfactory way is to 
 obtain the total head pumped against, exclusive of the 
 friction head, and add to it 5 to 15 per cent., depending 
 upon the complications in the circuit. Substituting the 
 above in formula 98, we obtain 
 
 89000 X 323 
 
 /. H. P. = = 22.3 
 
 60 X 33000 X .65 
 
 Work out the value hf by (73) and see how nearly it 
 checks with the above. 
 
 162. Boilers: A number of boilers will necessarily be 
 installed in a plant of this kind, and a good arrangement is to 
 have them so piped with water and steam headers that any 
 number of the boilers may be used for steaming purposes 
 and the rest as water heaters. They should also be so ar- 
 ranged that any of the boilers may be thrown out of service 
 for cleaning or repairs and still carry on the work of the 
 plant. By doing this the boiler plant becomes very flexible 
 and each boiler is an independent unit. Any good water tube 
 boiler would serve the purpose, both as a steaming and as a 
 heating boiler. Where the boilers are used as heaters, the 
 water should enter at the bottom and come out at the top. 
 Where the water enters at the top and comes out at the bot- 
 tom, the excessive heating of the front row of tubes retards 
 the circulation of the water by this heat, and produces a rapid 
 circulation through the rear tubes where the heat is the 
 least. This rapid circulation in the rear tubes is not a detri- 
 ment, but it is less needed there than in the front ones. It 
 would be decidedly better if the rapid circulation were in the 
 front row, causing the heat from the fire to be carried off 
 more readily, and by this means giving less danger of burn- 
 ing the tubes. In the latter case the forced circulation from 
 the pumps will be aided by the natural circulation from the 
 
224 HEATING AND \ENTILATION 
 
 heat of the fire, and the life of all the tubes then becomes 
 more uniform. Fig. 99 shows a typical header arrangement. 
 Boilers are usually classified as fire tube and water tube. 
 Fire tube boilers are usually of the multitubular type, having 
 the flue gases passing through the tubes and water sur- 
 rounding them. Water tube boilers have the water passing 
 through the tubes and the flue gases surrounding them, 
 The heating surface of a boiler is composed of those boiler 
 plates having the heated flue gases on one side and the water 
 on the other. A toiler horse power may be taken, as follows: 
 
 Centennial Rating. 
 
 One B. H. P. = 30 pounds of water evaporated from feed 
 water at 100 F. to steam at 70 pounds gage pressure. 
 
 A. S. M. E. Rating. 
 
 One B. H. P. 34.5 pounds of water evaporated from 
 and at 212 F. 
 
 In laying out a boiler plant some good approximations 
 for the essential details are: 
 
 One B. H. P. = 11.5 square feet of heating surface 
 
 (multitubular type). 
 One B. H. P. = 10 square feet of heating surface 
 
 (water tube type). 
 One B. H. P. = .33 square feet of grate surface 
 
 (small plant, say one boiler). 
 One B. H. P. .25 square feet of grate surface 
 
 (medium sized plant, say 500 H. P.). 
 One B. H. P. .20 square feet of grate surface 
 
 (large plants). 
 
 Pounds of water evaporated per square foot of heating 
 surface per hour = 3 (approx. value). 
 
 163. Square feet of Hot \Vater Radiation that can be 
 Supplied on a Zero Day by One Boiler Horse Power when the 
 Boiler is Used as a Heater: Assuming that the coal used in 
 the plant has a heating value of 13000 B. t. u. per pound, 
 and that the efficiency of the boiler is 60 per cent., each 
 pound of coal will transmit to the water 7800 B. t. u. Since 
 each pound of water takes up 25 B. t. u. on its passage 
 through the heating boiler, one pound of coal will heat 312 
 pounds, or 37.5 gallons of water. This is equivalent to 
 supplying heat, under extreme conditions of heat loss, to 
 
DISTRICT HEATING 225 
 
 37.5 square feet of radiation for one hour. One boiler horse 
 power, according to Art. 162, is equivalent to the expendi- 
 ture of 969.7 X 34.5 = 33455 B. t. u. Now since each pound 
 of coal transfers to the water 7800 B. t. u., one boiler horse 
 power will require 33455 -^ 7800 = 4.28 pounds of coal. If, 
 then, the burning of one pound of coal will supply 37.5 square 
 feet of hot water radiation for one hour, one boiler horse 
 power will supply 4.28 X 37.5 = 160 square feet for one 
 hour, and a 100 H. P. boiler will supply 16000 square feet 
 of water radiation in the district for the same time. These 
 figures have reference to boilers under good working con- 
 ditions and probably give average results. 
 
 164. Square Feet of Hot Water Radiation in the District 
 that can be Supplied on a Zero Day by an Economizer Lo- 
 cated in the Stack Gases between the Boilers and the Chim- 
 ney: (In order to make this estimate it is necessary first to 
 know the horse power of the boilers, the amount of coal 
 burned per hour, the pounds of gases passing through the 
 furnace per hour and the heat given off from these gases 
 to the circulating water through the tubes. 
 
 APPLICATION. Let C pounds of coal burned per hour = boiler 
 .horse power X pounds of coal per boiler horse power hour, Wa 
 = pounds of air passed through the furnace per pound of fuel 
 burned, s = specific heat of the gases, U = temperature of 
 gases leaving boiler, t s = temperature of gases leaving econ- 
 omizer, t w =. temperature of water entering economizer 
 and tf = temperature of water leaving the economizer 
 Then, if 8.33 pounds of water will supply one square foot 
 of radiation for one hour we have, 
 
 8 X (C X Wa + O) X U s U) 
 
 Rw = (99) 
 
 8.33 X (t t t w ) 
 
 Prom a previous statement, 44500 pounds of steam 
 per hour is generated in the steam boiler plant at a 
 pressure of 125 pounds gage. To find the boiler horse 
 power, let the total heat of the steam, above 32 at 125 
 pounds gage, be 1191.8 B. t. u., and let the temperature 
 of the incoming feed water to the boilers be 60 degrees. 
 (In most cases the feed water will be at a higher tempera- 
 ture, but since it will occasionally be as low as 60 degrees, 
 this value will be a fair one.) The heat put into a pound 
 of steam under these conditions is 1191.8 (60 32) = 1163.8 
 B. t. u., and in 44500 pounds it will be 51789100 B. t. u. 
 
226 HEATING AND VENTILATION 
 
 Since one horse power of boiler service is equivalent to 33455 
 B. t. u., we will need 51789100 -4- 33455 = 1548 boiler horse 
 power. This horse power will take care of all the engines 
 and pumps in the plant. If the coal used contains 13000 
 B. t. u. per pound and the boilers have 60 per cent, effi- 
 ciency, then 7800 B. t. u. will be given to the water per 
 pound of fuel burned, and the amount of coal burned per 
 hour will be 51789100 -f- 7800 = 6640 pounds. This gives 
 6640 -f- 1548 = 4.3 pounds of fuel per boiler horse power 
 hour, and 6.7 pounds of water evaporated per pound of fuel. 
 If the flue gases have 12 per cent. CO 2 , there are being used 
 according to experimental data, about 21 pounds of air or 
 22 pounds of the gases of combustion, per pound of fuel 
 burned. This is equivalent to 6640 X 22 = 146080 pounds of 
 flue gases total. Suppose now that these gases leave the 
 furnace for the chimney at a temperature of 550 degrees 
 F., that the economizer drops the temperature of the gases 
 down to 350 degrees (a condition which is very reasonable) 
 and that the specific heat of the gases is about .22, we have 
 146080 X .22 X (550 350) = 6427520 B. t. u. given off from 
 the gases per hour in passing through the economizer (see 
 numerator in formula 99). This heat is taken up by the 
 circulating water in passing through the economizer to- 
 ward the outgoing main. Now if the water, as it returns 
 from the circulating system, enters the economizer at 155 
 degrees, and leaves at 180 degrees, we will have 6427520 
 -T- (180 155) = 257100 pounds of water heated per hour. 
 This is equivalent to supplying 257100 -f- 8.33 = 30864 square 
 feet of radiation per hour when the plant is running at 
 its peak load. Taking the "pounds of steam per hour" in 
 the above as the only variable quantity, we are fairly safe 
 in saying that the heat in the chimney gases from one horse 
 power of steaming boiler service will supply, through an 
 economizer, 30864 -T- 1548 = 20 square feet of radiation in the 
 district. In plants where only 7 pounds of water is allowed 
 to each square foot of radiation per hour, this becomes 23.8 
 square feet of radiation instead. 
 
 165. Square Feet of Economizer Surface Required to 
 Heat the Circulating Water In Art. 164: Let K = the coeffi- 
 cient of heat transmission through clean cast iron tubes and 
 E the efficiency of the tube surface when in average serv- 
 
DISTRICT HEATING 227 
 
 Ice, also, let the terms for the temperatures of the gases 
 and the circulating water be as given in Art. 164, then 
 
 Heat trans, per hour from gases to water 
 
 / tb + t a tf + t w \ 
 
 KXEXl ) 
 
 V 2 27 
 
 (100) 
 
 This formula assumes that the rate of heat flow through 
 the tubes is the same at all points. As a matter of fact this 
 rate changes slightly as the water becomes heated, but 
 the error is not worth mentioning in such a formula, where 
 the efficiency of the surface may be anything from 100 per 
 cent, in new tubes, to as low as 30 or 40 per cent, for old 
 ones. 
 
 APPLICATION. Let K = 1 and E = .4, then 
 
 6427520 
 .R e = - = 8125 sq. ft. 
 
 / 550 + 350 180 + 155 
 
 7X .4 X 
 
 2 2 
 
 With 12 square feet of surface per tube this gives 677 tubes. 
 
 166. Square Feet of Economizer Surface to Install when 
 the Economizer is to be Used to Heat the Feed Water for 
 the Steaming Boilers: If 30 pounds of feed water are fed 
 to the boiler per horse power hour, and if K = 7, E = .4, 
 tb = 550, t s = 350, tf = 250, and t w = 90 (about the lowest 
 temperature at which water should enter the economizer), 
 then the square feet of surface per horse power is 
 
 30 X (250 90) 
 R e = = 6.1 sq. ft. 
 
 550 + 350 250 + 90 \ 
 
 7 X .4 X 
 
 2 2 / 
 
 167. Total Capacity of the Boiler Plant and the Number 
 of Boilers Installed: The following discussion on the size 
 of the boiler plant is purely for illustrative purposes and 
 is intended to show how such problems may be analyzed. 
 In most cases the exhaust steam, and the economizer if used, 
 will fall far short of supplying the total radiation in the 
 district, especially when the electrical output is light and 
 the weather is cold. Suppose it be desired to install extra 
 boilers to be used as heaters for the radiation not supplied 
 from these two sources. To determine the amount of ex- 
 tra boilers, find the amount of radiation to be supplied by 
 
228 HEATING AND VENTILATION 
 
 the exhaust steam and the economizer and subtract this 
 from the total radiation. The difference must be supplied 
 by boilers used as heaters. It is probably not safe to esti- 
 mate too closely on the amount of exhaust steam given to 
 the heating system. The maximum amount of 44500 pounds 
 per hour was obtained, in this case, by pumping one gal- 
 lon of water per hour for each square foot of radiation and 
 by pumping city water, in addition to that obtained from 
 the engines. In heating, a less amount of water than this 
 may be circulated even on the coldest day. This is -possi- 
 ble, first, because water may be carried at a higher tem- 
 perature than that stated, and second, because there may 
 be less loss of heat in the conduit, thus giving more heat per 
 gallon of water to the radiation. Again, in estimating for 
 a city water supply, the demands are not very constant and 
 are difficult to estimate. In this one design it was thought 
 that 44500 pounds per hour was a very liberal allowance 
 and could be dropped to 35000 pounds (140000 square feet 
 of radiation), when estimating the amount of radiation 
 supplied by the exhaust steam. 
 
 By Fig. 94 it will be seen that the minimum load on the 
 steaming boilers carries through six hours out of the entire 
 twenty-four and that the exhaust steam at this time drops 
 to 22890 pounds per hour, supplying 91560 square feet of 
 radiation. This minimum load is 51 per cent, of the max- 
 imum, and 66 per cent, of the amount taken as an average 
 i. e., 35000. The work done by the economizer is fairly con- 
 stant, since the amount of economizer surface lost by the 
 steaming boilers under minimum load would be made up 
 t>y the additional heating boilers thrown into service. On 
 the basis of 35000 pounds per hour, the exhaust steam and the 
 stack gases together would heat 170960 square feet and 
 there would be left 13540 square feet (184500 20 X 1548 
 4 X 35000), to be heated by additional boilers. Under 
 minimum load this would be approximately 122500, leaving 
 62000 square feet to be heated by additional boilers. If one 
 boiler horse power will supply 160 square feet of radiation, 
 then it would require 84 and 387 boiler horse power re- 
 spectively to supply the deficiency and the total horse power 
 needed in each case would be 1632 and 1935. A more satis- 
 factory analysis, however, is the following which is worked 
 on the lasis of 44500 pounds per hour. 
 
DISTRICT HEATING 229 
 
 Let Ws = total number of pounds of steam used in the 
 plant per hour = approximate number of pounds of exhaust 
 steam available for heating the circulating water per hour; 
 We = equivalent number of pounds of steam evaporated froir> 
 and at 212; \ = total heat, above 32, in one pound of dry 
 steam at the boiler pressure; q 1 = total heat, above 32, in 
 one pound of feed water entering the boiler; then, if the 
 latent heat of steam at atmospheric pressure = 969.7 B. t. u., 
 we have 
 
 W* (A a 1 ) 
 
 We = (101) 
 
 969.7 
 
 and the corresponding boiler horse power needed as steam' 
 ing boilers will be 
 
 We 
 
 B S H. P. = (102) 
 
 34.5 
 
 Next, the radiation in the district that can be supplied 
 by the exhaust steam is Rw = 4 W s , and the amount sup- 
 plied by the economizer is Re = 20 X B. H. P. From which 
 we may obtain the capacity of the heating boilers as, 
 
 Total Radiation 4 W s 20 B. H. P. 
 
 Bw H. P. = (103) 
 
 160 
 
 The total boiler horse power of the plant is, therefore, the 
 sum of B s H. P. and B w H. P. To obtain formula 103 for any 
 specific case one must consider the maximum and minimum 
 conditions of the steaming boiler plant. Let W s (max) 
 maximum exhaust steam, and W s (min) = minimum exhaust 
 steam. Then for the two following conditions we will have, 
 Case 1, where the steaming and heating boilers are independent of 
 each other, the total boiler horse power installed == B s H. P. 
 + [total radiation 4 W s (min) 20 X 7?. H. P. in use] + 
 160; Also, Case 2, where a part or all of the steaming boilers are 
 piped for loth steaming and water service, the total boiler horse 
 power installed = B s H. P. + [total radiation 4 W s (max) 
 20 X B. H. P. in use] -j- 160. It will be noticed that the last 
 term representing the economizer service is simply stated 
 as boiler horse power and no distinction is made between 
 steaming or heating service. This term will be difficult to 
 estimate to an exact figure because it should be the total 
 horse power in use at any one time, both steaming and heat- 
 ing, and this can only be obtained by approximation. It 
 makes no difference what service the boiler may be used for, 
 the work of the economizer would be practically the same. 
 
230 HEATING AND VENTILATION 
 
 Probably the most satisfactory way is to substitute the value 
 B a H. P. for B. H. P. in the economizer and get the approxi- 
 mate total horse power, then if this approximate total horse 
 power differs very much from that actually needed, other 
 trials may be made and new values for the total horse power 
 obtained until the equation is satisfied. 
 
 Application. Let W s = pounds of exhaust steam, ^ = 
 1191.8 (125 pounds gage pressure), and q' = 28 (feed water 
 at 60); then when W B = 44500 
 
 W e = 53400 
 
 B s H. P. = 1548 
 
 184500 4 X 22890 20 X 1548 
 
 B w H. P. Case 1 = = 387 
 
 160 
 184500 4 X 44500 20 X 1548 
 
 B w H. P. Case 2 = = 153 
 
 160 
 
 This shows that there is an excess of waste heat in Case 2, 
 making a total boiler horse power, Case 1, = 1935 and Case 
 2, = 1548. Investigating Case 1 to see what error was intro- 
 duced by using 1548 in the economizer, we find approximately 
 800 horse power of steam boilers in use, and the total horse 
 power to be 1187, which is about 360 horse power on the 
 unsafe side. Substitute again and check results. Case 2 is 
 reasonably close. In any case the most economical size of 
 boiler plant to install in a plant requiring both steaming and 
 heating boilers is one where at least a part, if not all, of the 
 boilers are piped so as to be easily changed from one system 
 to the other. By such an arrangement the capacity may be 
 made the smallest possible. After obtaining the theoretical 
 size of the plant, it would be well to allow a small margin 
 in excess so that one or two boilers may be thrown out of 
 commission for repairs and cleaning without interfering 
 with the working of the plant. Case 2 seems to be the better 
 arrangement. Assuming 1800 total boiler horse power we 
 might very well put in six 300 H. P. boilers arranged in three 
 batteries. 
 
 168. Cost of Heating from a Central Station (Direct Fir- 
 ing) : It will be 'Of interest in this connection to estimate 
 approximately the cost in supplying heat by direct firing to 
 one square foot of hot water radiation per year from the 
 average central station. In doing this make the boiler as- 
 sumptions to be the same as Art. 163. Take coal at 13000 
 
DISTRICT HEATING 
 
 231 
 
 Fig. 
 Power Plant Layout. 
 
232 HEATIXG AXD VEXTILATIOX 
 
 R. t. u- per pound, 2000 pounds per ton, and a boiler effi- 
 
 ciency of per cent. "Water enters the boiler at 155 degrees 
 from the returns, and is delivered to the mains at 180 de- 
 grees. From the value of the coal as stated, we would have 
 15*0000 B. t. u. per ton given off to the water. This is 
 
 equivalent to h eating- 24000 pounds, or 74&10 gallons, of 
 water. If one ton of coal costs $2.00 at the plant, we have 
 
 200 -j- 74S10 = .0027 cents 
 
 This represents the amount paid to reheat one" gallon of 
 water, or to supply one s-quare foot of heading surface one 
 tour at an outside temperature of zero degrees. Take the 
 average temperature for the seven cold months at 32 de- 
 grees. This is the average for the coldest year in the twenty 
 years preceding 1&10. as recorded at the U. S. Exp. Station, 
 LaFayette. Indiana. "We then have an average difference 
 between the inside and the outside temperatures in any 
 residence of 7t 32 = 2S. This makes the formula for 
 the heat loss. Art. 2*, reduce to 3S -E- 70 = .54 of its 
 former value. Now, if it takes one gallon of water per 
 square foot of radiation per hour under maximum conditions, 
 we have for the seven months .54 X ! X Zb S. 24 = 2722 gal- 
 lons of water needed for each square foot of radiation per 
 each healing year. This is equivalent to 2722 y .0027 = 7.35 
 cents per square foot of radiation for the heating year of 
 seren months. 
 
 When the plant is working under the best conditions 
 this figure should be reduced. It tian be done with boilers 
 of a higher eJideaey than that stated, and it can be done 
 by using a cheaper coal, both of which are possible in many 
 
 1C*. Cwrt of Hratfms from a Oatral Station, 
 f Tests: The following tests were conducted upon the 
 Merchants R^atfng and Lighting Plant, LaFayette, Ind.; one 
 in 19M and the other in 1M8. The plant was changed slight- 
 ly between the two tests and the radiation carried upon the 
 liaes was much increased, although tm all essential features 
 the pHsit was the Miar. The circulating water was heated 
 by rmhsast steam beaters and by heating boilers. 
 
 The plant had the following important pieces of appara- 
 tus employed hi grarisliag or absorbing the heat supply: 
 
DISTRICT HEATING 233 
 
 BOILERS (Steaming and Heating). 
 
 Two 125 11. P. Stirling boilers. Total heating surface 
 2524 sq. ft. 
 
 Three 250 H. P. Stirling boilers. Total heating surface 
 7572 sq. ft. 
 
 Pressure on steaming boilers (gage), 150 Ibs. 
 
 Pressure on heating boilers (approx.), 60 Ibs. 
 
 ENGINES. 
 
 One 450 H. P. Hamilton Corliss comp. engine, direct con- 
 nected to a 300 K. W. Western Electric 72-pole alternating 
 current generator 120 R. P. If. This engine carried the load 
 of the plant when it was above 50 K. W., which was generally 
 from 5:30 A. M. to 11:30 P. M. When this unit was run, direct 
 current was obtained by passing the alternating current 
 through a motor generator set. 
 
 One 125 H. P. Westinghouse comp. engine, belted to one 
 75 K. W. 3-phase alternating and two direct current genera- 
 tors, and run at 312 R. P. M, This unit was generally run 
 between 11:30 P. M. and 5:30 A. ivi. 
 
 One 250 H. P. Westinghouse comp. engine, belt connected 
 to a 200 K. W. generator and two smaller machines. 
 
 PUMPS. 
 
 One centrifugal, two-stage pump, Dayton Hydraulic Co., 
 direct connected to a Bates vertical high speed engine at 300 
 R. P. M. 
 
 Two Smith-Vaile horizontal recip. duplex pumps 14 in. 
 X 12 in. X 18 in. Each of the three pumps connected to the 
 return main in such a way as to be able to use any combina- 
 tion at any one time to circulate the water. The centrifugal 
 pump had been in service only one season. It had a capacity 
 about equal to the two reciprocating pumps and under the 
 heaviest service this pump and one of the duplex pumps 
 were run in parallel. 
 
 One Smith-Vaile horizontal reciprocating tank pump 
 6 in. X 4 in. X 6 in. to lift the water of condensation from 
 the exhaust heater to the tank. 
 
 One Smith-Vaile horizontal reciprocating make-up pump 
 6 in. X 4 in. X 6 in. to replace the water that was lost from 
 the system. 
 
234 
 
 HEATING AND VENTILATION 
 
 Two National horizontal reciprocating boiler feed pumps. 
 
 One 9% in. Westinghouse air pump, to keep up the supply 
 of air through the conduits to the regulator system in the 
 heated buildings. 
 
 One Deane vertical deep well pump, to deliver fresh 
 water to the supply tank. 
 
 One Baragwanath exhaust steam heater or condenser, 
 having 1000 sq. ft. of heating surface. 
 
 PARTIAL SUMMARY OF RESULTS. 
 
 1906 
 
 1. Square feet of radiation 118000 
 
 2. Temperature of circulating water in 
 degrees F.-, flow main 158.36 
 
 3. Temperature of circulating water in 
 degrees P., return main 139.9 
 
 4. Temperature of circulating water in 
 degrees F., after leaving heater 145.6 
 
 5. Temperature of outside air in de- 
 grees F 32.6 
 
 6. Temperature of stack gases in de- 
 grees F., steaming boiler 
 
 7. Temperature of stack gases in de- 
 grees F., heating boiler 562. 
 
 8. Draft in stacks (all boilers averaged) 
 
 in inches of water . 68 
 
 9. Heating value of coal in B. t. u. 
 
 per pound 12800 
 
 10. B. t. u. delivered to steaming boiler 
 
 per hour by coal .18187000 
 
 11. B. t. u. delivered to heating boilers 
 
 per hour by coal 19226000 
 
 12. B. t. u. delivered to circulating water 
 
 by heating boilers per hour 11800000 
 
 13. B. t. u. to be charged to heating boil- 
 ers (Item 12 Item 15) 7650000 
 
 14. B. t. u. delivered to circulating water 
 by exhaust steam from tne gener- 
 ating engines per hour 3600000 
 
 1908 
 150000 
 
DISTRICT HEATING 
 
 235 
 
 15. B. t. u. thrown away during test 
 from pump exhausts and available 
 
 for heating- circulating water 4150000 8471000 
 
 16. B. t. u. available for heating- circu- 
 lating water from all exhaust steam 
 as in normal running (Item 14 + 
 
 Item 15) 7750000 15073000 
 
 17. Total B. t. u. given to circulating 
 
 water per hour (Item 13 + Item 16) . .15400000 22007000 
 
 18. Gallons of water pumped per hour 
 
 [Item 17 (8.33 X Items 2-3)] 100000 108000 
 
 19. Gallons of water pumped per square 
 foot of radiation per hour (Item 18 
 
 -^ Item 1) .85 .70 
 
 20. Efficiency of heating boilers (Item 
 
 12 -~ Item 11) approx .60 .55 
 
 21. Value of the coal in cents per ton of 
 
 2000 pounds at the plant 200. 175. 
 
 22. Average electrical horse power 68 141 
 
 Note. The above values are averages and were taken 
 for each entire test. The B. t. u. values were considered sat- 
 isfactory when approximated to the nearest thousand. 
 
 170. Regulation: The regulation of the heat within the 
 residences is best controlled from the power plant. In most 
 heating plants a schedule is posted at the power house which 
 tells the engineer the necessary temperature of the circu- 
 lating water to keep the interior of the residences at 70 
 degrees with any given outside temperature. In other heat- 
 ing plants the regulation is by means of air carried from the 
 compressor at the power house through a main running 
 parallel with the water mains in the conduits and branching 
 to each building where it is used under a pressure of 15 
 pounds to operate thermostats, which in turn control the 
 water inlets to the radiators. A closer regulation is ob- 
 tained in the latter system than in the former, but it is 
 needless to say that the thermostats require careful adjust- 
 ments and frequent inspections. 
 
236 HEATING AND VENTILATION 
 
 STEAM SYSTEMS. 
 
 171. Heating by steam from a central station, compared 
 with hot water heating, is a very simple process. The power 
 plant equipment is composed of a few inexpensive parts, the 
 operation of which is very simple and easily explained. 
 These parts have but few points that require rational de- 
 sign. Because of the simplicity and because of the similarity 
 to the preceding discussion on hot water systems, the work 
 on steam systems will be very brief. All questions referring 
 to the construction of the conduit, the supporting of the 
 pipes, the provision for contraction and expansion, the drain- 
 ing of the pipes and the draining of the conduits, are com- 
 mon to both hot water and steam systems and are discussed 
 in Arts. 135 and 136. A large part of the work referring 
 directly to district hot water heating applies with almost 
 equal force to steam heating. This part of the work, there- 
 fore, will deal with such parts of the power plant equipment 
 as differ from those of the hot water system. 
 
 'Steam heating may be classified under two general heads, 
 high pressure and low pressure. A very small part, only, of 
 the heating in this country is now done by what may be 
 strictly called high pressure service, i. e., where radiators or 
 coils are under pressures from 30 to 60 pounds gage, and 
 this small amount is gradually decreasing. Ordinarily, steam 
 is generated at high pressure at the boiler, 60 pounds to 150 
 pounds gage, and reduced for line service to pressures vary- 
 ing from to 30 pounds gage, with a still further reduction 
 at the building to pressures varying from to 10 pounds 
 gage, for use in radiators and coils. Where exhaust steam 
 is used in the main, the pressure is not permitted to go higher 
 than 10 pounds gage, because of the back pressure on the 
 engine piston. Where exhaust steam is not used, the pres- 
 sures may go, as high as 30 pounds gage, thus allowing for a 
 greater pressure drop in the line and a corresponding re- 
 duction in pipe sizes. 
 
 The principles involved in the power plant end of 
 a steam heating system may be represented by Fig. 100. It 
 will be seen that the exhaust steam from the engines or tur- 
 bines has four possible outlets. Passing through the oil : 
 separator, which removes a large part of the entrained oil, i 
 part of the exhaust steam is turned into the heater for use in i 
 
DISTRICT HEATING 
 
 237 
 
 heating the boiler feed water. The rest of the steam passes 
 on into the heating system. If there be more exhaust steam 
 than is necessary to supply the heating system, the balance 
 may go to the atmosphere through the back pressure valve. 
 When the heating system is not in use, as would be the case 
 in the four warm months of the year, the exhaust steam may 
 be passed into the condenser. 
 
 Fig. 100. 
 
 It is very evident, from what has been said before, that 
 it would not be economical to condense the steam in a con- 
 denser as long as there is a possibility of using it in the 
 heating system. The increased gain in efficiency, when con- 
 densing the exhaust steam under vacuum, is very small com- 
 pared to the gain when this same steam is used for heating 
 purposes. It would also be very poor economy to use any live 
 steam for heating when there were any exhaust steam 
 wasted. When the amount of exhaust steam is insufficient, 
 live steam is admitted through a pressure reducing valve. 
 
 172. Drop in Pressure and the Diameter of the Mains: 
 
 The flow of steam in a pipe follows the same general laws as 
 the flow of water. The loss of head may be represented 
 by the well known formula 
 
 Ji f = (104) 
 
 9d 
 
 where hf = loss of head in feet, < = coefficient of friction, 
 v = velocity in feet per second, I length of pipe in feet, 
 
238 HEATING AND VENTILATION 
 
 d = diameter of the pipe in feet and g = 32.2. Substitute, hi = 
 144 p -+- D, where p = drop in pressure in pounds and D = den- 
 sity of the steam, and find 
 
 2 </> lv 2 
 
 P = (105) 
 
 144 gd 
 
 The coefficient of friction is found to vary with the velocity of 
 the steam and with the diameter of the pipe. Prof. Unwin 
 found, that for velocities of 100 feet per second (good prac- 
 tice for transmission lines), it could be expressed as follows, 
 where c is a constant to be found by experiment, 
 
 -\ ) 
 
 10 d ) 
 which, when substituted in (105), gives 
 
 lv 2 Dc 
 
 72 gd 
 
 Let TF = pounds of steam passing per minute and efi = diam- 
 eter of pipe in inches, then 
 
 , = -_( + i ace, 
 
 1 / 3.6 \ W 2 lc 
 
 P = ( 1 H ) (107) 
 
 20.663 \ di / d^D 
 
 From this formula we may obtain any one of the three terms, 
 W, d^ or p, if the other two are known. Table 31, Appendix, 
 was compiled from (107) with c = .0027. For discussion, see 
 Trans. A. S. M. E., Vol. XX, page 342, by Prof. R. C. Carpen- 
 ter. Also Encyclopedia Britannica, Vol. XII, page 491. See 
 also, Kent, page 670, and Carpenter's H. & V. B., page 51. 
 
 It will be seen that Table 31 is compiled upon the basis 
 of one pound pressure drop, at an average pressure of 100 
 pounds absolute in the pipe. Since, in any case, the drop 
 In pressure is proportional to the square of the pounds of 
 steam delivered per minute (other terms remaining constant), 
 the amount delivered at any other pressure drop than that 
 given (one pound) would be found by multiplying the amount 
 given in the table by the square root of the desired pressure 
 drop in pounds. Also, since the weight of steam moved at 
 the same velocity, under any other absolute pressure, is ap- 
 proximately proportional to the absolute pressures (other 
 terms remaining constant), we have the amount of steam 
 moved under the given pressure, found by multiplying the 
 amount given in the table by the square root of the ratio of 
 the absolute pressures. To illustrate the use of the table 
 
DISTRICT HEATING 239 
 
 suppose the pressure drop in a 1000 foot run of 6 inch pipe 
 is 8 ounces, when the average pressure within the pipe is 10 
 pounds gage. The amount of steam carried per minute is 
 93.7 X V^5 -r V100 -T- 25 = 133 pounds. Or, if the drop is 4 
 pounds, at an average inside pressure of 50 pounds gage, 
 the amount carried would be 150 pounds per minute. Con- 
 versely find the diameter of a pipe, 1000 feet long, to carry 
 150 pounds of steam pe.r minute, at an average pressure 
 of 10 pounds gage and a pressure drop of 8 ounces. 
 
 150 JfTHT" 
 
 W (table) = X J = 264 poun ds 
 
 V.5 ^ 65 
 
 which, according to the table, gives a 9 inch pipe. 
 
 173. Dripping: the Condensation from the Mains: The 
 
 condensation of the steam, which takes place in the con- 
 duit mains, should be dripped to the sewer or the return 
 at certain specified points, through some form of steam 
 trap. These traps should be kept in first class condition. 
 They should be inspected every seven or ten days. No pipe 
 should be drilled and tapped for this water drip. The only 
 satisfactory way is to cut the pipe and insert a tee with 
 the branch looking downward and leading to the trap. The 
 sizes of the traps and the distances between them can only be 
 determined when the pounds of condensation per running 
 foot of pipe can be estimated. 
 
 174. Adaptation to Private Plants: District steam heat- 
 ing systems may be adapted to private hot water plants by 
 the use of a "transformer." This in principle is a hot water 
 tube heater which takes the place of the hot water heater 
 of the system. It may also be adapted to warm air systems 
 by putting the steam through indirect coils and taking the 
 air supply from over the coils. 
 
 175. General Application to the Typical Design: The 
 
 following brief applications are meant to be suggestive of the 
 method only and the discussions of the various points are 
 omitted. 
 
 Square feet of radiation in the district. 
 
 R 8 = 184500 X 170 4- 255 = 123000 square feet. 
 
 Amount of heat needed in the district to supply the radiation for 
 one hour in zero weather. 
 
 Total heat per hour = 123000 X 255 = 31365000 B. t. u. 
 
240 HEATING AND VENTILATION 
 
 Amount of heat necessary at the power plant to supply the radiation 
 for one hour in zero weather. Assuming 15 per cent, heat loss in 
 the conduit (this is slightly less than that allowed for the 
 hot water two-pipe system, 20 per cent.), we have, 
 31365000 -=- .85 = 36900000 B. t. u. per hour. 
 
 Total exhaust steam available for heating purposes. 
 1F S (max) = (23100 + 8680) X 1.15 36547 pounds per hour. 
 W s (min) = ( 1490 -f 8680) X 1.15 = 11696 pounds per hour. 
 
 Total B. t. u. available from exhaust steam per hour for heating. 
 Let the average pressure in the line be 5 pounds gage and 
 let the water of condensation leave the indirect coils in the 
 residences at 140 degrees. We then have from one pound of 
 exhaust steam, by formula 75, 
 
 B. t. u. = .85 X 960 + 195.6 (140 32) 903.7 
 Assuming this to be 900 B. t. u. per pound, the total available 
 heat from the exhaust steam for use in the heating system is, 
 maximum total = 32892300 B. t. u. and the minimum total 
 10526iOn B. t. u. 
 
 Square feet of steam radiation that can be supplied by one pound 
 of exhaust steam at 5 pounds gage. 
 
 tf s = 900 -r- (255 -f- .85) = 3. 
 
 Total B. t. u. to be supplied by live steam. 
 
 B. t. u. (max load) = 36900000 32892300 = 4007700 B. t. u. 
 B. t. u. (min. load) = 36900000 10526400 = 26373600 B. t. u. 
 
 Total pounds of live steam necessary to supplement the exhaust 
 steam. Let the steam be generated in the boiler at 125 
 pounds gage. With feed water at 60 degrees 
 
 Max. load = 4007700 -j- 1163.8 = 3444 pounds. 
 Min. load = 26373600 -j- 1163.8 = 22661 pounds. 
 
 Boiler horse power needed for the steam power units. As in 
 Arts. 164 and 167, 
 
 B s H. P. (max.) = 36547 X 1.2 -=- 34.5 = 1271. 
 B s H. P. (min.) = 11696 X 1.2 -r- 34.5 = 407. 
 
 Total "boiler horse power needed in the plant. Maximum load. 
 B. H. P. (total) 1271 + (3444 X 1.2 4- 34.5) = 1391. 
 
 It will be noticed that this total horse power is 157 horse 
 power less than the corresponding Case 2 in Art. 167. This 
 is accounted for by the fact that no steam is used up in work 
 in the circulating pumps, also that the conditions of steam 
 generation and circulation are slightly different. 1500 boiler 
 horse power would probably be installed in this case. 
 
DISTRICT HEATING 
 
 241 
 
 Size of Conduit Mains. Let it be required to find the 
 diameters of the mains system in Jig. 96 at the important 
 points shown. Art. 144 gives the length of the mains in each 
 part. Allow .3 pound of steam for each square foot of steam 
 radiation per hour (this will no doubt be sufficient to supply 
 the radiation and conduit losses). Try, first, that part of the 
 line between the power plant and A, with an average steam 
 pressure in the lines of about 5 pounds gage and a drop in 
 pressure of iy 2 ounce per each 100 feet of run (approximately 
 5 pounds per mile). 25200 pounds per hour gives TF = 420. 
 The length of this part of the line is 200 feet and the drop 
 is 3 ounces, or .19 pound. 
 
 TF (table) = 
 
 420 / 
 
 /J9- X V 
 
 100 
 
 V . 
 
 = 2158 pounds 
 
 which gives a 15 inch pipe. 
 
 Following out the same 
 line, we have 
 
 TABLE XXVIII. 
 
 reasoning for all parts of the 
 
 
 PPtoA 
 
 AtoB 
 
 BtoC 
 
 CtoD 
 
 DtoE 
 
 Distance between points _ 
 
 200 
 
 500 
 
 1500 
 
 1500 
 
 500 
 
 Radiation supplied, sq. ft - 
 
 84000 
 
 57000 
 
 34000 
 
 19000 
 
 8000 
 
 Pressure-drop in pounds = p 
 
 .19 
 
 .47 
 
 1.4 
 
 1.4 
 
 .47 
 
 Diameter of pipe in inches, by table 
 
 15 
 
 13 
 
 11 
 
 9 
 
 5 
 
 In general practice, these values would probably be taken 
 16, 14, 12, 10 and 6 inches respectively. Look up Table 30, 
 Appendix, and check the above figures. 
 
242 HEATING AND VENTILATION 
 
 REFERENCES. 
 
 References on District Heating. 
 
 TECHNICAL BOOKS. 
 
 Allen, Notes on Heating and Ventilation, p. 131. 
 TECHNICAL PERIODICALS. 
 
 Engineering Netcs. Comparison of Costs of Forced-Circula- 
 tion Hot Water and Vacuum-Steam Systems, J. T. Maguire, 
 Dec. 23, 1909, p. 692. Design of Hot-Water System with 
 Forced-Circulation, J. T. Maguire, fc>ept. 2, 1909, p. 247. En- 
 gineering Review. Determining Depreciation of Underground 
 Heating Pipes, W. A. Knight, Jan. 1910, p. 85. Some Remarks 
 on District Steam Heating, W. J. Kline, April 1910, p. 61. 
 Toledo Yaryan System, A. C. Rogers, May 1910, p. 58. Some 
 of the Factors that Affect the Cost of Generating and Dis- 
 tributing Steam for Heating. C. R. Bishop, Aug. 1910, p. 56. 
 Central Station Heating Plant at Crawf ordsville, Ind., B. T. 
 Gifford, Dec. 1909, p. 42. Wilkesbarre Heat, Light and Motor 
 Co., A Live Steam Heating Plant, J. A. White, July 1908, p. 32. 
 The Heating and Ventilating Magazine. Schott Systems of Central 
 Station Heating, J. C. Hornung, Nov. 1908, p. 19. Data on 
 Central Heating Stations, Nov. 1909, p. 7. Cost of Heat from 
 Central Plants, March 1909, p. 31. Steam Heating in Con- 
 nection with Central Stations, Paul Mueller, Oct. 1909, p. 24; 
 Nov. 1909, p. 1. A Modern Central Hot Water Heating Sta- 
 tion, W. A. Wolls, July 1910, p. 15. Central Station Heating, 
 F. H. Stevens, June 1910, p. 5. Domestic Engineering. Report 
 of Second Annual Convention of the National District Heating 
 Association at Toledo, O., June 1, 1910. Vol. 51, No. 11, June 
 11, 1910, p. 255. 
 
CHAPTER XIV. 
 
 TEMPERATURE CONTROL IN HEATING SYSTEMS. 
 
 176. From tests that have been conducted on heating 
 systems, it has been conclusively proven that there is less 
 loss of heat from buildings supplied by automatic tempera- 
 ture control, than from buildings where there is no such con- 
 trol. A uniform temperature within the building is desir- 
 able from all view-points. Where heating systems are oper- 
 ated, even under the best of conditions, without such control, 
 the efficiency of the system would be increased by its appli- 
 cation. No definite statement can be made for the amount of 
 heat saved, but it is safe to say that it is between 5 and 20 
 per cent. A building uniformly heated during the entire 
 time, requires less heat than if a certain part or all of the 
 building were occasionally allowed to cool off. When a 
 building falls below normal temperature it requires an extra 
 amount of heat to bring it up to normal, and when the inside 
 temperature rises above the normal, it is usually lowered by 
 opening windows and doors to enable the heat to leave rap- 
 idly. High inside temperatures also cause a correspondingly 
 increased radiation loss. E luctuations of temperature, there- 
 fore, are not only undesirable for the occupants, but they 
 are very expensive as well. 
 
 177. Principles of the System: Temperature control may 
 be divided into two general classifications, small plants 
 and large plants. The control for small plants, i. e., such plants 
 as contain very few heating units, is accomplished by regu- 
 lating the drafts by special dampers at the combustion cham- 
 ber. This method controls merely the process of combustion 
 and has no especial connection with individual registers or 
 radiators, it being assumed that a rise or fall of temperature 
 in one room is followed by a corresponding effect in all 
 the other rooms. This method assumes that all the heating 
 units are very accurately proportioned to the respective 
 rooms. The dampers are operated through a system of 
 levers, which system in turn is controlled by a thermostat. 
 Fig. 101 shows a typical application of such regulation. 
 
244 
 
 HEATING AND VENTILATION 
 
 Fig. 101. 
 
 This may be applied to 
 any system of heat. In 
 addition to the ther- 
 mostatic control from 
 the room to the damper, 
 as has just been men- 
 tioned, closed hot water 
 systems and steam and 
 vapor systems should 
 have regulation from the 
 pressure within the 
 boiler to the draft. Oc- 
 casionally in the morn- 
 ing the pressure in 
 either system may be- 
 come excessive before 
 the house is heated 
 enough for the thermo- 
 stat to act. With such 
 
 additional regulation no hot water heater or steam boiler 
 would te forced to a dangerous pressure. I ig. 102 shows a 
 thermostat manufactured by the Andrews Heating Co., Minne- 
 apolis. The complete regulator has in addition 
 to this, two cells of open circuit battery and a 
 motor box, all of which illustrate very well the 
 thermostatic damper control. 
 
 The thermostat operates by a differential 
 expansion of the two different metals com- 
 posing the spring at the top. Any change in 
 temperature causes one of the metals to ex- 
 pand or contract more rapidly than the other 
 and gives a vibrating movement to the project- 
 ing arm. This is connected with the batteries 
 and with the motor in such a way that when 
 the pointer closes the contact with either one 
 of the contact posts, a pair of magnets in the 
 motor causes a crank arm to rotate through 
 180 degrees. A flexible connection between this 
 crank and the damper causes the damper to 
 open or close. A change in temperature in 
 the opposite direction makes contact with the other post 
 and reverses the movement of the crank and damper. The 
 movement of the arm between the contacts is very small thus 
 
TEMPERATURE CONTROL 
 
 245 
 
 making the thermostat very sensitive. No work is required 
 of the battery except that necessary to release the motor. 
 
 Occasionally it is desir- 
 able to connect small heat- 
 ing plants having only one 
 thermostat in control, to a 
 central station system. Fig. 
 103 shows how the supply 
 of heat may be controlled 
 by the above method. 
 
 Fig. 104 shows the Syl 
 phon Damper Regulator 
 made by The American 
 Radiator Co., and applies 
 to steam pressure control. 
 The longitudinal expansion 
 of a corrugated brass or 
 copper cylinder operates 
 the damper through a sys- 
 tem of levers. The longitu- 
 dinal movement of the cyl- 
 inder is small and hence 
 the bending of the metal 
 in the walls of the cylinder 
 is very slight. This small 
 movement is multiplied 
 
 Fig. 104. 
 
246 
 
 HEATING AND VENTILATION 
 
 through the system of levers to the full amount necessary to 
 operate the damper. A similar device is made by the same 
 Company for application to hot water heaters. 
 
 Temperature control in large plants, i. e., those plants having 
 a large number of heating units, is much more complicated. 
 In furnace systems this is very much the same as described 
 under small plants, with additional dampers placed in the 
 air lines. The following discussions, therefore, will apply 
 to hot water and steam systems, and will be additional to the 
 control at the heater and boiler as discussed under small 
 plants. Fig. 105 shows a typical layout of such a system. 
 Compressed air at 15 pounds per square inch gage is main- 
 tained in cylinder, $, which is located in some convenient 
 
 Fig. 105. 
 
 place for the attendant. This air is car- 
 ried to the thermostat, T*, on one of the 
 protected walls in the room. Here it 
 passes through a controlling valve and 
 is then led to the regulating valve on the 
 radiator. T-his air acts on the top of a 
 rubber diaphragm as shown in Fig. 106 to 
 close the valve and to cut off the sup- 
 ply. When the room cools off, the con- 
 Fig. 106. trolling valve at Tn cuts off the supply 
 and opens the air line to the radiator. This removes the air 
 pressure above the diaphragm and permits the stem of the 
 
TEMPERATURE CONTROL 247 
 
 valve to lift. On the opening of the valve the steam or water 
 again enters the radiator and the cycle is completed. 
 
 Fig-. 66 shows the application of the thermostatic control 
 to the blower work. This shows the thermostat B and the 
 mixing dampers, located at the plenum chamber, in the 
 single duct system. The same general arrangement could 
 be applied to the double duct system, with the dampers in 
 the wall at the base of the vertical duct leading to the 
 room. 
 
 178. Some of the Important Points in the Installation of 
 such work are as follows. Each radiator has its own regu- 
 lating valve. All rooms having three radiators or less are 
 provided with one thermostat. Large rooms having four or 
 more radiators have two or more thermostats with not more 
 tuan three radiators to the thermostat. Where other mo- 
 tive power is not available for the air supply, a hydraulic 
 compressor is used. This compressor automatically main- 
 tains the air pressure at 15 pounds gage in the steel supply 
 tank. The main air trunk lines are galvanized iron, % and 
 % inch in diameter, and are tested under a pressure of 25 
 pounds gage. All branch pipes are J /4 and % inch galvanized 
 iron. All fittings on the % inch pipes are usually brass. Where 
 flexible connections are made, this is sometimes done by 
 armoured lead piping. Thermostats are usually provided 
 with metallic covers, and are finished to correspond with the 
 hardware of the respective rooms. Each thermostat is pro- 
 vided with a thermometer and a scale for making adjust- 
 ments. Each radiator is provided with a union diaphragm 
 valve having a specially prepared rubber diaphragm with felt 
 protection. This valve replaces the ordinary radiator valve. 
 One of these valves is used on the end of each hot water 
 radiator, one on each one-pipe steam radiator and two 
 on each two-pipe low pressure steam radiator. This last 
 condition does not hold for two-pipe steam radiators with 
 mechanical vacuum returns, in which case patented special- 
 ties are applied by the vacuum company. In such cases the 
 supply to the radiator only is controlled. In any first class 
 system of control, the temperature of the room may easily 
 be kept within a maximum fluctuation of three degrees. 
 
 179. Some Special Designs of Apparatus: All temperature 
 control work is solicited by Specialty Companies, each having 
 a patented system. In the essential features these systems 
 all agree with the foregoing general statements. The chief 
 
248 
 
 HEATING AND VENTILATION 
 
 difference is in the principle upon which the thermostat, 
 TK, operates. 
 
 Pig. 107 shows a section through the thermostat manu- 
 factured by The Johnson Service Co., Milwaukee. The air 
 comes from the supply tank through the pipe C and enters 
 
 Fig. 107 
 
 the thermostat through the cut off valve E. D leads to the 
 regulating valve at the radiator or damper. From the valve 
 E the air is led up to F. F is attached to the stem G which 
 passes up through the outlet H and carries the grooved 
 head I. If F be moved up to the inside opening of H, it 
 will close the opening and will open C to D. It is evident, 
 since F is against H, this air cannot escape to the atmosphere, 
 but passes to pipe D, thence to the regulating valve and 
 closes the hot water or steam valve or damper. Should the 
 valve F be again pushed to the right hand seat, the supply 
 of compressed air will again be closed off, the opening H will 
 be uncovered, the air that has been stored in the regulating 
 valve escapes, and the valves that have been shut are thereby 
 opened. From this it will be seen that as the air valve F is 
 either to the right or left, the main valve will be opened or 
 shut. The valve F is moved by the thermostat. When valve F 
 
TEMPERATURE CONTROL 249 
 
 is open the lead seat N is off the port M and a small amount 
 of air from the line C leaks through. This leakage is slight 
 and continues until N closes the port again. The real thermo- 
 stat is the spring P Q. These are steel and brass strips 
 brazed together in one piece. Because of a higher coefficient 
 of expansion in the one than in the other, a change in room 
 temperature causes N to move toward, or away from, the 
 seat. As soon as the temperature of the room drops sufficient- 
 ly, Q contracts more rapidly than P, and the port closes. The 
 leakage air is then confined under the diaphragm K and its 
 pressure increases until the lever W is forced out and 
 valve F is closed. By the closing of valve F, as stated above, 
 the air is exhausted from above the diaphragm in the regu- 
 lating valve and the radiator opens. The saddle R can be 
 adjusted so as to make the thermostat more or less sensi- 
 tive. To set the thermostat for any desired temperature 
 turn the adjusting post U until the pointer Y indicates the 
 proper temperature on the diaphragm ring. 
 
 The thermostat as here shown gives full movement to 
 the valve, i. e., full open and full closed. Other forms for 
 control are designed for graduated movement of dampers 
 where used in blower systems. 
 
 Fig. 108 shows a section through the pattern K thermo- 
 stat, manufactured by the Powers Regulator Co., Chicago. 
 This thermostat consists of a frame carrying two corrugated 
 disks, brazed together at the circumference and containing a 
 volatile liquid having a boiling point at about 50 degrees F. 
 At a temperature of about 70 degrees, the vapor within 
 the disks has a pressure of about 6 pounds to the square inch. 
 This pressure varies with every change of temperature and 
 produces variations in the total thickness at the center of 
 the disks. 
 
 The compressed air enters at H and passes into chamber 
 N through the controlling valve J, which is normally held to 
 its seat by a coil spring under cap P. Within the flange M 
 is located an escape valve L upon which the point of the 
 supply valve J rests. Valve L tends to remain open when 
 permitted by reason of the spring underneath the cap. When 
 the temperature rises sufficiently to cause the disks to in- 
 crease in thickness and move the flange M, the first action 
 is to seat the escape valve L, its spring being weaker than 
 that above J. If the expansive motion is continued after 
 
250 
 
 HEATING AND VENTILATION 
 
 valve L is seated, the valve J is then lifted from its seat 
 and compressed air flows into the chamber N. As the 
 air accumulates in chamber N, it exerts a pressure upon the 
 elastic diaphragm K in opposition to the expansive force of 
 the disk. So, whenever there is sufficient pressure in N to 
 balance the power exerted by the disks, the valve J returns 
 
 Fig. 108. 
 
 to its seat and no more air is permitted to pass through. 
 If the temperature falls, the pressure within the disks be- 
 comes less, the disks draw together and the over-balancing 
 air pressure in N reverses the movement of the flange M and 
 permits the escape valve L under the influence of its spring 
 to raise from its seat, whereupon a portion of the air in N 
 is discharged until the pressure in N becomes equal to the 
 diminished pressure from the disks. Thus the pressure of the 
 air in N is maintained always in direct proportion to the 
 expansive power (temperature) of the disks. Port J connects 
 with chamber N and leads to the diaphragm valve. 
 
 This thermostatic valve controls the- regulator valve by 
 a graduated movement and is used on the dampers for 
 
TEMPERATURE CONTROL, 
 
 251 
 
 blower work. Another form with maximum movement only 
 is designed for steam systems. 
 
 Fig. 109 shows sections through the positive movement 
 and the graduated movement thermostats, as manufactured 
 by The National Regulator Co., Chicago. In the left diagram 
 air enters the thermostat through the tube C, passes up 
 through the filter P to the port G, and from thence through 
 to a similar tube D to the regulating valve at the radiator. 
 G may be opened or closed according as the stem K controls 
 
 Fig. 109. 
 
 the lever O. The movement of lever is caused by the ex- 
 pansion and contraction of the vulcanized rubber tube A. 
 The adjusting screw J at the top is set to permit G to open 
 and close at any desired temperature. When the temperature 
 of the room rises above the normal temperature, tube A 
 expands, the pressure from K is released, tube G opens and 
 compressed air from the supply tank passes through to the 
 regulating valve and shuts off the heat. Upon lowering the 
 temperature in the room, tube A contracts, the pressure of 
 K on block M becomes greater, the port G closes, the con- 
 fined air in the tube D leading to the regulating valve is ex- 
 
252 HEATING AND VENTILATION 
 
 hausted to the atmosphere, and the heat is turned on. The 
 screw S is set so as to allow the air to pass through it in 
 very small quantities. 
 
 When a graduated movement is desired on the regulating 
 valve for use in air currents, the same thermostat with 
 slight modifications is used. In this case a single pipe only 
 leads to the thermostat. When the tube A expands from the 
 heat in the room, the pressure from the rod K is reduced and 
 the port G is closed. The air is now confined in the single 
 pipe, the pressure rises and the regulating valve is moved 
 in such a position as to cut off a part or all of the warm air 
 and admit tempered air. When the temperature in the room 
 falls, because of the admission of this cooler air, the tube A 
 contracts, and the port O is opened permitting the air to 
 escape and operate the damper in the reverse direction. The 
 amount of air admitted to the thermostat is controlled by a 
 needle valve, hence its sensitiveness can be controlled. 
 
CHAPTER XV. 
 
 ELECTRICAL, HEATING. 
 
 In the present state of the heating business it seems 
 almost unnecessary to discuss electrical heating, in any 
 serious way, in connection with steam power plants. The 
 reasons will be seen in the following brief discussion. 
 Electrical heating can appeal to the public only from the 
 standpoint of convenience, since a comparison of economies 
 between steam, hot water or warm air heating on one hand, 
 and electrical heating on the other, is wholly against the 
 latter. Its application to the processes of heating will find its 
 greatest economy in connection with water power plant 
 where the combustion of fuel is eliminated from the prop- 
 osition. This discussion will not bear in any way upon the 
 water power generator. 
 
 ISO. Equations Employed in Electrical Heating Design: 
 
 1 H. P. 746 watts. 
 
 1 H. P. = 33000 ft. Ibs. per min. 1980000 ft. Ibs. per hr. 
 
 1 B. t. u. = 778 ft. Ibs. 
 
 1 H. P. hr. = 1980000 -r- 778 = 2545 B. t. u. per hr. 
 
 1 H. P. hr. = 746 watt hrs. = 2545 B. t. u. per hr. 
 
 1 watt hr. = 3.412 B. t. u. per hr. 
 
 1 watt hr. 3.412 -f- 170 .02 sq. ft. of hot water rad. 
 
 1 watt hr. = 3.412 -^ 255 = .0134 sq. ft. of steam rad. 
 
 1 kilo-watt hr. = 20.1 sq. ft. of hot water rad. (108) 
 
 1 kilo-watt hr. = 13.4 sq. ft. of steam rad. (109) 
 
 181. Comparison between Electrical Heating and Hot 
 Water and Steam Heating: The loss in transmitting electric- 
 ity from the generators through the switchboard to the radi- 
 ators may be small or large, depending upon the conditions 
 of wiring, the current transmitted and the pressure on the 
 line. In all probability it would equal or exceed the trans- 
 mission losses in hot water or steam lines. Assuming these 
 losses to be the same, then a fair comparison may be made 
 in the cost of heating by the various methods. The operating 
 efficiency of an electric heater is 100 per cent., since all the 
 current that is passed into the heater is dissipated in the 
 form of heat and no other losses are experienced. This is 
 
254 HEATING AND VENTILATION 
 
 not true of steam systems where the water of condensation 
 is thrown away at fairly high temperatures. Where elec- 
 tricity or steam is generated and distributed all in the same 
 building, there is no line loss to be accounted for, since all 
 of this heat goes to heating the building and counts as 
 additional radiation. 
 
 Equations 108 and 109 show the theoretical relation 
 existing between electrical heating and hot water and steam 
 heating compared at the power plant. The following dis- 
 cussion is based, therefore, upon the assumption that 1 
 kilo-watt hour, in an electric radiator, will give off the same 
 amount of heat as 20.1 and 13.4 square feet of hot water and 
 steam radiation respectively. With coal having 13000 B. t. u. 
 per pound and a furnace efficiency of 60 per cent., it will 
 require 3412 -7- 7800 = .44 pounds of coal per hour. If coal 
 co,sts $2.00 per ton of 2000 pounds, there will be an actual 
 fuel expense of .044 cent. On the other hand, assuming the 
 combined mechanical efficiency of an engine or turbo-gener- 
 ator set to be 90 per cent., the heat from the steam that is 
 turned into electrical energy per hour is 1000 ~ .90 = 1111 
 watts, for each kilo-watt delivered. Now, if this unit has 
 15 per cent thermal efficiency, we have the initial heat in 
 the steam equivalent to 1111 -r- .15 = 7400 watt hours. From 
 this obtain 7400 X 3.412 = 25249 B. t. u. per hour; or, 25249 
 -^ 7800 = 3.2 pounds of coal per hour. This, at the same 
 rate as .shown above, would be worth .32 cent. Comparing, 
 the electrical generation actually costs 7.2 times as much as 
 the other. This comparison has dealt with the fuel costs at 
 the plant and has not taken into account the depreciation, 
 labor costs, etc., the object being to show relative efficiencies 
 only. 
 
 Another way of looking at this subject is as follows. 
 A fairly large turbo-generator set (say 500 K. W.) will 
 deliver 1 kilo-watt hour to the switchboard on 20 pounds 
 of steam. With 10 per cent, additional steam for auxiliary 
 units, this amounts to 22 pounds of steam per kilo-watt hour 
 at the switchboard. One pound of steam generated in a 
 plant of this kind with the above efficiencies and value of coal, 
 also with a ,steam pressure of 150 pounds and a good feed 
 water heater, will give to each pound of steam approximately 
 1000 B. t. u. This makes 22000 B. t. u. or 2.8 pounds of coal 
 required to each kilo-watt output. This is about 10 per cent, 
 less than the above figures. 
 
ELECTRICAL HEATING 255 
 
 The ratio of 7 to 1, as shown in the above efficiencies, 
 does not seem to hold good in the selling price to the con- 
 sumer. In round numbers, district steam and hot water heat- 
 ing systems supply 25000 B. t. u. to the consumer for one 
 cent. The cost for electrical energy to the consumer is be- 
 tween 6 and 7 cents per kilo-watt. This gives 3412 -r- 6.5 
 525 B. t. u. for one cent. Comparing with the above, gives 
 a ratio of 48 to 1. 
 
 182. The Probable Future of Electrical Heating: Be- 
 cause of the low efficiency of electrical heating as compared 
 to other methods of heating, it is very probable that it will 
 not replace the other methods except in so far as the con- 
 veniences of the user is the principal thing sought for, and 
 the expense of operating a minor consideration. In some 
 forms of domestic service, however, electrical heating is 
 sure to find considerable usefulness. The temperatures of 
 low pressure steam and hot water* together with the incon- 
 venience of use, are such as to eliminate them from many 
 of the household economies. They will probably continue 
 to be used for house heating, water heating and laundry 
 work. Occupations, however, that require temperatures 
 above 250 degrees, such as broiling, frying, ironing, etc., the 
 electrical supply will be in demand. 
 
 REFERENCES. 
 
 References on Electrical Heating. 
 
 TECHNICAL PERIODICALS. 
 
 The Heating and Ventilating Magazine. Electrical Heating, 
 5 eb. 1907, p. 28. Electric Heating, W. S. Hadaway, Jr., Nov. 
 1908, p. 28; Dec. 1908, p. 26. The Electrical World, Vol. 52, pages 
 450, 903, 1112 and 1358, and Vol. 53, pages 5, 274 and 921. 
 
CHAPTER XVI. 
 
 SUGGESTIONS FOR A COURSE OF INSTRUCTION. 
 
 183. Preparation for the Course: In adapting this sub- 
 ject to a college course, it should, if possible, be taken up 
 during the last year of college work, when the ^student can 
 have the benefit of a large part of the training in Heat, 
 Thermodynamics, Engineering Design, and Steam Engines 
 and Boilers, all of which subjects are of great value in 
 heating and ventilating work. The subjects of Heat and 
 Thermodynamics prepare for analytical and experimental 
 investigation in heat transference, while a knowledge of 
 engines, boilers and general machinery gives information 
 of a more practical turn, the application of which is neces- 
 sary in heating design. A course of study, as outlined here, 
 is primarily theoretical but it should not stop there. To 
 be of service in fitting a man for active participation in the 
 work after leaving school, it must emphasize such points 
 as relate to the layout of the drawings and to the mate- 
 rials used in the construction as well. A course fitted to 
 practical needs should not only require a full set of cal- 
 culations for each design, but it should require a complete 
 layout of each system. 
 
 184. Administration of the Work: The course should be 
 administered, part in the class room, as lectures and reci- 
 tations, and part (a set of designs) should be left to the 
 student to work up largely upon his own responsibility and 
 submit the same for approval. 
 
 The work in the class room should be at least two 
 hours per week, and may be divided between lectures and 
 recitations in whatever manner is thought best. In the lec- 
 tures, references should be made to the various authorities 
 on heating and ventilating with suggestions that these 
 authorities be looked up. The lectures should also include 
 very full details concerning the laying out of such work, 
 with suggestions concerning the proper selection of ma- 
 terials. The recitations should be made as practical as 
 possible to serve in bringing out the points that would 
 probably be confusing in developing the designs. All class 
 
OUTLINE OB A COURSE 257 
 
 room work should be timed to suit the design under con- 
 sideration, otherwise the design work and the class room 
 work will be independent rather than mutually helpful. 
 
 185. Outline of the Work of Design: After two or three 
 weeks devoted to the subjects of ventilation, radiating sur- 
 faces, etc., the work of design should be taken up and 
 might very properly cover the following systems of heat- 
 ing: 
 
 1. Furnace heating, as applied to residences. Time al- 
 lowed, three weeks. 
 
 2. Hot water heating, as applied to residences. Time 
 allowed, three weeks. 
 
 3. Steam heating, as applied to residences. Time al- 
 lowed, two weeks. 
 
 4. Plenum system of warm air heating, as applied to 
 schools and low office buildings. Time allowed, 
 four weeks. 
 
 5. District heating from a Central Station. Time al- 
 lowed, four weeks. 
 
 The above will be found to cover the work very thor- 
 oughly and should be administered in such a way as to 
 remove as much of the purely routine work as ppssible, 
 otherwise the course which is planned for one-half year's 
 work would be too long for the time allowed to the aver- 
 age student by the school curriculum. As an illustration, 
 the student prepared for this work is fairly well qualified 
 to make mechanical drawings, and any relief which can be 
 given from drawing work will permit the equivalent time 
 being put to other and more important parts of the design. 
 This relief can take the form of prepared building plans 
 stamped off on standard sized paper, thus permitting the 
 insertion of heating drawings on the same pages without 
 the routine labor of reproducing an entirely new set of 
 drawings. These plans may be made the same size as the 
 blanks upon which the calculations are submitted, say, 8% 
 x 11 inches and should always be different from any pre- 
 viously given. The final report will then include every 
 thing under one cover and can be filed away without dif- 
 ficulty. For sample set of building plans, see Figs. 13, 14 
 and 15, with the furnace, pipes and registers removed. 
 
 186. Specifications: It is desirable that each man have 
 experience in writing specifications for his own plans. This is 
 
258 HEATING AND VENTILATION 
 
 difficult for a beginner and requires considerable time to d<t 
 properly. It is thought best, therefore, to present a brief 
 set of specifications (see Chapter XVII) to show how such 
 work is done and let this set be used to g'ive suggestions 
 for the more complete set. Originality in form and sim- 
 plicity and accuracy of statement are the principal points 
 to be observed. The instructor should use his own dis- 
 cretion in deciding how comprehensive these specifications 
 shall be. 
 
 INSTRUCTIONS FOR DESIGN REPORTS. 
 
 Nos. 1, 2 and 3. 
 Furnace, Hot Water and Steam Systems. 
 
 The first three design reports in heating and ventila- 
 tion cover three lines of residence heating, i. e., furnact-, 
 hot water and steam. Three complete sets of plants of the 
 same house are supplied to each member of the class, upon 
 which the heating designs may be made. With these duplicate 
 plans, the heat loss need be calculated once only for the 
 three designs. Upon submitting report No. \, a copy of the 
 heat loss should be made to use on Nos. 2 and 3. 
 
 Each man shall submit designs which he has himself 
 worked up. No objection will be raised to two or more 
 students working simultaneously, checking each other's 
 figures and in a general way profiting by good suggestions. 
 It is objectionable, however, to divide the work so that each 
 man does only a part. Designs that, in the opinion of the 
 instructor, have been copied, will be rejected and marked 
 zero. 
 
 Each design will be submitted in a manilla cover 
 properly filled out with the name of the designer, the name 
 of the design and the date. If the design was worked up 
 in conjunction with any other person or persons, these 
 names should be given. 
 
 For the convenience of the instructor, each report will 
 be arranged as follows: 
 
 1. Blank sheet for instructor's corrections. 
 
 2. Title page with statement of the design. 
 
 3. Specification sheets. 
 
 4. Plans; basement, first floor and second floor. 
 
 5. Summary table, after the pattern of Table IX. 
 
 6. Calculations and notes. 
 
OUTLINE OP A COURSE 259 
 
 The reports are returned after correction. 
 
 The calculations in the furnace design will include, for 
 each room, the heat loss, the cubic feet of air needed 
 each room as a heat carrier (this should be checked for 
 ventilation), the heat loss (by formula), the cubic feet of air 
 needed per hour and the areas of the net registers, gross 
 registers, stacks and leaders; also, for the entire plant, the 
 air supply ducts and the grate. Specify the type and size 
 of the furnace installed. 
 
 The calculations in the hot water design will include 
 the heat loss, the radiation in square feet per room, the 
 radiator pipe sizes, the riser pipe sizes, the sizes of the 
 general mains (show on plans), the gallons of water heat- 
 ed per hour, the size of the expansion tank (locate on 
 pla'ns) and -the type and size of the heater installed. 
 
 The calculations in the steam design will include the 
 heat loss, the radiation in square feet per room, the radiator 
 pipe sizes, the riser pipe sizes, the sizes of the general mains 
 (show on plans), the pounds of steam condensed per hour 
 total and the type and size of the boiler installed. 
 
 In drawing the mains on the plans, it is suggested to 
 use red ink for the supply mains and black ink for the re- 
 turn mains 'to avoid confusion. It is also suggested to use 
 arrows to denote the direction of flow within the pipes. 
 
 The reports will be submitted as follows: 
 
 No. 1 19 
 
 No. 2 , 19 
 
 No. 3 19 
 
 INSTRUCTIONS FOR DESIGN REPORT. 
 
 No. 4. 
 Plenum Warm Air System. 
 
 These instructions, together with the three building 
 plans (not shown here but same as Figs. 74, 75 and 76 
 with the heating plants removed), will form the basis upon 
 which to design a plenum system of warm air heating for 
 the building shown. Each room is numbered and should 
 be referred to in the report by that number. The heat loss 
 for each floor will be estimated from some acceptable 
 formula. If Carpenter's formula is used, take 
 
260 HEATING AND VENTILATION 
 
 Basement, (walls only two-thirds exposed,) n = 1. 
 
 First floor, (walls fully exposed) n = iy z . 
 
 Second floor, (same as first floor). 
 
 Corridors, n = 2. 
 
 In the calculations the following points should be 
 worked up for each room: the heat loss, the cubic feet of 
 air per hour as a heat carrier (this should then be checked 
 for ventilation), the net area of the register in square 
 inches, the catalog size of the register (as 12 x 14 inches) 
 and the size of the wall duct (as 8 x 10 inches). Bind also 
 the following: the size of the fresh air entrance; the size 
 of the main leader at the plenum chamber and the sizes 
 of the principal branches; the square feet of heating surface; 
 the lineal feet of coils; the net wind area at the coils; the 
 gross area at the coils and the arrangement of the coils 
 in sections; the horse power and the revolutions per min- 
 ute of the fan, including the sizes of the inlet and the 
 outlet of the fan; and the horse power of the engine in- 
 stalled, including the diameter and the length of the stroke. 
 In addition to the above, select one of the most important 
 rooms and find the temperature of the air at the registers 
 when excess air is required for ventilation. 
 
 The principal work on the plans will be to lay out the 
 basement equipment. The engine and fan will be placed in 
 room .... and should contain all the necessary pieces of 
 apparatus which go to make up the complete blower sys- 
 tem. Show on the plans the location of the tempering and 
 heating coils, how the air is taken from the outside of the 
 building, is passed through the blower into the plenum 
 chamber and thence through a system of ducts to the 
 various parts of the building. 
 
 It is understood that the steam is to be received at 
 the building under a maximum gage pressure of, say, 30 
 pounds per square inch, and is to be used in the coils under 
 a pressure of not over 5 pounds gage. This reduction will 
 be accomplished by the use of a pressure reducing valve. 
 Arrange the coils and piping so either exhaust steam or 
 live steam may be used in all the coils. Generally the ex- 
 haust steam from the fan engine is used in the tempering 
 coils and live steam in the main heating coils. After esti- 
 mating the total amount of heating surface, divide this into 
 tempering and heating coils. 
 
OUTLINE OE A COURSE 261 
 
 A back pressure valve should be placed on the exhaust 
 line opening to the air at the roof to relieve excessive back 
 pressure on the engine. Oil and steam separators should 
 also be installed. 
 
 It is suggested that a separate plate be made of the 
 heater room to avoid complications in drawing. This plate 
 should contain a plan and elevation with all piping connec- 
 tions and necessary valves clearly shown. 
 
 Design No. 4 will be submitted 19 
 
 INSTRUCTIONS FOR DESIGN REPORT. 
 No. 5. 
 
 Centralized Hot Water or Steam System. 
 
 These instructions together with the plan of the city, 
 Fig. 92, showing the portion of the city to be heated, will 
 
 form the basis upon which to design a centralized 
 
 heating system for the said locality. The plant will be 
 installed in connection with the municipal lighting and 
 
 pumping stations located at and 
 
 streets. In reconstructing the present plant the building 
 will not be used. The equipment, which may be considered 
 as new, is as follows. (Italics indicate variable terms.) 
 
 1, 250 K. W. direct current generator, direct driven from a 
 cross compound non condensing slow speed, Corliss engine. 
 
 1, 150 K. W. direct current generator, direct driven from a 
 simple non condensing high sp^ed engine. 
 
 1, 7J K. W. alternating current generator, direct driven 
 from a simple non condensing high speed engine. 
 
 2, 1^ million gallon, horizontal reciprocating duplex, city 
 water supply pumps, size 14 and 20x12x10 inch. When the pump 
 is in action, the pressure head against the pump is 60 
 pounds and the suction head is 10 pounds per square inch. 
 
 The small apparatus in the plant requiring steam (boil- 
 er feed pumps, etc.) may be assumed at 15 per cent, of the 
 total steam consumption of the large units. 
 
 3, 250 H. P. water tube boilers are at present supplying 
 the plant with steam. 
 
 If a hot water system is used, pumps will be installed 
 to circulate the hot water in the heating system. This 
 will necessitate an enlargement of the present steaming 
 boiler plant. In addition to this, extra boiler service may 
 be necessary to be used as heaters or steamers for the heat- 
 
262 HEATING AND VENTILATION 
 
 ing system to make up for the deficiency of exhaust steam. 
 The heating capacity of the system should be limited to, 
 say 125000 square feet of steam radiation, or 187500 square 
 feet of hot water radiation. 
 
 Only that part of the city shown between the dotted 
 lines will be considered desirable heating territory. 
 Allow, say 9000 square feet of hot water radiation or 
 6000 square feet of steam radiation to the four sides of a 
 business square, and about half of this to the four sides of a 
 residence square. 
 
 In working up this design, investigate and plan for the 
 following points: the probable number of square feet of 
 heating surface in the district; the layout of the street 
 mains with a section of the conduit; the sizes of the mains 
 at the plant and at several distant points in the system, 
 the number and sizes of the circulating pumps; the load 
 curve of the plant and the amount of exhaust steam per 
 hour available; the size of and the square feet of heating 
 surface in the .exhaust steam heaters for the circulating 
 system, if used; the boiler horse power total and how it is 
 divided into units; the economizer surface total and how it 
 is divided into units; the chimney diameter and height, and 
 the complete layout of the plant including the arrangement 
 of the engines, boilers, pumps, heaters, pipes, etc. 
 
 Design No. 5 will be submitted 19... 
 
CHAPTER XVII. 
 
 PLANS AND SPECIFICATIONS FOR HEATING SYSTEMS. 
 
 O wiiei- 
 cr 
 Purchaser 
 
 187. In Planning: for and Executing Engineering Con- 
 irnctM, the responsibilities assumed by the various interested 
 parties should be thoroughly studied. The following outline 
 shows the relationship between these parties and the order of 
 the responsibility. 
 
 Engineer. 
 
 Superintendent and Inspector. 
 
 General contractor, Subcontractors, Foremen and 
 Workmen. 
 
 The engineer, the superintendent and the general con- 
 tractor occupy positions of like responsibility with relation 
 to the purchaser. The first two work for the interest of the 
 purchaser to obtain the best possible results for the least 
 money, and the last endeavors to fulfill the contract to the 
 'satisfaction of the superintendent, at the least possible 
 expense to himself. These view-points are quite different 
 and sometimes are antagonistic, but both are right and just. 
 Of the three parties, the engineer has the greatest respon- 
 sibility. It is his duty to draw up the plans and to write 
 the specifications in such a way, that every point is made 
 clear and that no question of dispute may arise between the 
 superintendent and the contractor. His plans should detail 
 every part of the design with full notes. His specifications 
 should explain all points that are difficult to delineate on the 
 plans. They should give the purchaser's views covering all 
 preferences, and should definitely state where and what ma- 
 terials may be substituted. Where any point is not definitely 
 settled and left to the judgement of the contractor, he may 
 be expected to interpret this point in his favor and use the 
 cheapest material that in his judgment will give good re- 
 sults. This opinion may differ from that held by the pur- 
 chaser. All parts should be made so plain that no two opin- 
 ions could be had on any important point. The engineer 
 should also be careful that the plans and specifications agree 
 in every part. The inspector is the superintendent's repre- 
 sentative on the grounds and is supposed to inspect and 
 
264 HEATING AND VENTILATION 
 
 pass upon all materials delivered on the grounds, and the 
 quality of workmanship in installing. For such information 
 see Byrne's "Inspector's Pocket-Book". The general con- 
 tractor generally sublets parts of the contract to subcon- 
 tractors who work through the foreman and workmen to 
 finish the work upon the same basis as the general con- 
 tractor. 
 
 The following brief set of specifications are not con- 
 sidered complete but are merely inserted to suggest how 
 such work is done. 
 
 Typical Specifications. 
 
 TITLE PAGE: 
 
 SPECIFICATIONS 
 
 for the 
 
 MATERIALS AND WORKMANSHIP 
 Required to Install 
 
 (Type of system) 
 HEATING AND VENTILATING SYSTEM 
 
 in the 
 (Building) 
 
 (Location) 
 by 
 
 (Name of desig-ner) 
 
 INDEX PAGE: 
 
 (To be compiled after the specifications are written.) 
 
 General Remarks to Contractor. In the following- specifi- 
 cations, all references to the Owner or Purchaser will mean 
 
 or any person or persons delegated by 
 
 to serve as the representative. The Super- 
 intendent of Buildings will be the purchaser's representative at 
 
TYPICAL SPECIFICATIONS 265 
 
 all times, unless otherwise definitely stated. The contractor 
 will, therefore, refer all doubtful questions or misunder- 
 standings, if any, to the Superintendent, whose decision will 
 be final. In case of any doubt concerning 1 the meaning of 
 any part of the plans or specifications, the contractor shall 
 obtain definite interpretation from the superintendent be- 
 fore proceeding with the work. 
 
 These specifications with the accompanying plans and 
 details (Sheets .... to .... inclusive) cover the purchase of 
 all the materials as specified later (the same materials to 
 be new in every case), and the installation of the same in a 
 first class manner within the above named building, located 
 at (street) (city) (state). 
 
 It will be understood that the successful bidder, herein- 
 after called the contractor, shall work in conformity with 
 these plans and specifications and shall, to the best of his 
 ability, carry out their true intent and meaning. He shall 
 purchase and erect all materials and apparatus required to 
 make the above system complete in all its parts, supplying 
 only such quality of materials and workmanship as will har- 
 monize with a first class system and develop satisfactory 
 results when working under the heaviest service to which 
 such plants are subjected. 
 
 The contractor shall lay out his own work and be re- 
 sponsible for its fitting to place. He shall keep a competent 
 foreman on the grounds and shall properly protect his work 
 at all times, making good any damage that may come to it, 
 or to the building, or to the work of other contractors from 
 any source whatsoever, which may be chargeable to himself 
 or to his employees in the course of their operations. 
 
 Any defects in materials or workmanship, other than 
 as stated under (state exceptions if any) that may develop 
 within one year, shall be made good by the contractor upon 
 written notification from the purchaser without additional 
 cost to the purchaser. 
 
 The contractor shall, wherever it is found necessary, 
 make all excavations and back-fill to the satisfaction of the 
 superintendent. 
 
 The contractor shall be responsible for all cuttings of 
 wood work, brick work or cement work, found necessary 
 in fitting his materials to place, either within or without the 
 building; the cutting to be done to the satisfaction of the 
 superintendent. The contractor shall be required to connect 
 
266 HEATING AND VENTILATION 
 
 and supply water and gas for building purposes, and shall 
 assume all responsibility for the same. 
 
 The contractor shall be required to protect the purchaser 
 from damage suits, originating from personal injuries re- 
 ceived during the progress of the work; also, from actions 
 at law because of the use of patented articles furnished by 
 the contractor; also, from any lien or liens arising because 
 of any materials or labor furnished. 
 
 The purchaser reserves the right to reject any or all 
 bids. 
 
 No changes in these plans and specifications will be 
 allowed except upon written agreement, signed by both the 
 contractor and the purchaser's representative. 
 
 System. Specify the system of heating in a general way. 
 High pressure, low pressure or vacuum. Direct, direct- 
 indirect or indirect radiation. Basement or attic mains. 
 One or two-pipe connections to radiators. If ventilation is 
 provided, state the movement of the air and the general 
 arrangement of fans, coils or other heating surfaces. Single 
 or double duct air lines, etc. 
 
 Boilers. 'Specify type, number, size and capacity, steam, 
 pressure, approximate horse power, heating surface, grate 
 surface and kind of coal to be used. Locate on plan and ele- 
 vation. Explain method of setting, portable or brick. Specify 
 also, flue connection, heating and water pipe connections, 
 kind of grate, thermometers, gages, automatic damper con- 
 nection, firing tools and conditions of final tests. 
 
 Conduits and Conduit Mains. (In this it is assumed that the 
 boilers are not within the building). In addition to the lay- 
 out, give sections of the conduit on plans showing method 
 of construction, supporting and insulating pipes, and drain- 
 age of pipes and conduits. Specify quality and size of mate- 
 rials, pitch and drainage of pipes and all other points not 
 specially provided for in the plans. 
 
 Anchors. Locate and draw on plans and specify for the 
 installation regarding quality of materials. 
 
 Expansion Joints or Take-ups. Locate and draw on plans. 
 Select type of joint and specify for amount of safe take-up 
 and for quality of material. 
 
 Mains and Returns. Trace the steam from the point where 
 it enters the main, through all the special fittings of the 
 
 system. Show where the condensation is dripped 
 
 to the returns through traps or separating devices. Specify 
 
TYPICAL SPECIFICATIONS 267 
 
 amount and direction of pitch, kind of fittings (flanged or 
 screwed, cast iron or malleable iron), kind of corners (long 
 or short), method of taking up expansion and contraction. 
 Trace returns and specify dry or wet. 
 
 Branches to Risers. Take branches from top of mains by 
 tees, short nipples and ells, and enter the bottom of the 
 risers by sufficient inclination to give good drainage. 
 
 Risers. Locate risers according to plan. They shall be 
 straight and plumb and shall conform to the sizes given on 
 the plans. No riser shall overlap the casing around win- 
 dows. State how branches are to be taken off leading to 
 radiators, relative to the ceiling or floor. 
 
 Radiator Connections. Specify, one-pipe or two-pipe, num- 
 ber and kind of valves, sizes of connections and hand or 
 automatic control. All connections shall allow for good 
 drainage and expansion. Distinguish between wall radiator 
 and floor radiator connections. If automatic control is used, 
 hand valves are usually omitted. 
 
 Radiators. Specify floor or wall radiators, with type, 
 height, number of columns and number of sections. If other 
 radiators are substituted for the ones that are referred to 
 as acceptable, they must be of equal amount of surface and 
 acceptable to the Superintendent. Specify brackets for wall 
 radiators, also, air valves for all radiators, stating type 
 and location on the radiator. Require all radiators to be 
 cleaned with water or steam at the factory and plugged at 
 inlet and outlet for shipment. 
 
 Piping. Define quality, weight and material in all mains, 
 branches and risers. All sizes above one and one-half inch 
 are usually lap welded. Piping should be stood on end and 
 pounded to remove all scale before going into the system. 
 All pipes 1 inch and smaller should be reamed out full size 
 after cutting. 
 
 Fittings. Specify quality of fittings, whether light, stan- 
 dard or heavy, malleable or cast iron. P ittings with imper- 
 fect threads should be rejected. 
 
 Valves. Specify type (globe, gate or check), whether 
 flanged or screwed, rough or smooth body, cast iron or 
 brass, and give pressure to be carried. All valves should 
 be located on the plans. 
 
 Expansion Tank. 'Specify capacity of tank in gallons, kind 
 of tank (square or round, wood or steel), method of connect- 
 ing up with fittings and valves, and locate definitely on plan 
 
268 HEATING AND VENTILATION 
 
 and elevation. Connect also to fresh water supply and to 
 overflow. 
 
 Hangers and Ceiling Plates. Wall radiators and horizontal 
 runs of pipe shall be supported on suitable expansion hang- 
 ers or wall supports that will permit of absolute freedom of 
 expansion. Supports shall be placed .... feet centers. Pipe 
 holes in concrete floors shall be thimbled. Holes through 
 wooden walls and floors shall have suitable air space around 
 the pipe, and all openings shall be covered with ornamental 
 floor, ceiling or wall plates. 
 
 Traps. Specify type, size, capacity and location. State 
 whether flanged or screwed fittings are used and whether 
 by-pass connection will be put in. Refer to plans. 
 
 Pressure Regulating Valve. Specify type, size and location, 
 also, maximum and minimum steam pressure, with guaran- 
 tee to operate under slight change of pressure. State if 
 by-pass should be used and explain with plans. 
 
 separators. Specify type (horizontal or vertical), also 
 size and location. 
 
 Automatic Control. The contractor will be held responsible 
 for the installation of all thermostats, regulator valves, air 
 compressor, piping and fittings required to equip all rooms 
 and halls with an automatic .... temperature control sys- 
 tem. Specify ^approximate location and number of thermo- 
 stats with the desired finish. Specify in a general way, reg- 
 ulator valves on radiators, quality of pipe, maximum test 
 pressure for pipe, power for air supply (hydraulic, pneu- 
 matic, etc.), and supply tank. All the materials in the tem- 
 perature control system shall be guaranteed first class by 
 the manufacturer through the contractor, and the system 
 shall be guaranteed to give perfect control for a period of 
 (two) years. 
 
 Fans. Specify for direct connected or belt driven, right 
 or left hand, capacity, size, housing, direction of discharge, 
 horse power, R. P. M. and pressure. State in a general way 
 the requirements of the fan wheel, steel plate housing, shaft, 
 bearings and the method of lubrication. 
 
 Engine. Specify type, horse power, steam pressure, 
 approximate cut-off, speed and kind of control. 
 
 Electric Motors. Specify type, horse power, voltage, 
 cycles, phases and R. P. M. 
 
 Indirect Heating Surface. Specify the kind of surface to 
 be put in and then state the total number of square feet 
 
TYPICAL SPECIFICATIONS 269 
 
 of surface, with the width, height and depth of the heater. 
 State definitely how the heaters will be assembled, giving 
 free height of heater above the floor. Describe damper con- 
 trol, steam piping to and from heater, housing around heater, 
 connection from cold air inlet to heater and connection from 
 heater to fan. See plans. The contractor will usually follow 
 installation instructions given by the manufacturers for the 
 erection of the heater and engine, consequently the speci- 
 fications should only bear heavily upon those points which 
 may be varied to suit any condition. All valves, piping and 
 fittings in this work should be controlled by the general 
 specifications referring to these parts. 
 
 Foundations. Specify materials and sizes. 
 
 Air Ducts, Stacks and Galvanized Iron Work. The drawings 
 should give the layout of all the air lines, giving connections 
 between the air lines and the fan and the air lines and the 
 registers. Where these air lines are below the floor, the 
 conduit construction should be carefully noted. All gal- 
 vanized iron work should be shown on the plans and the 
 quality and weight should be specified. Air lines should 
 have long radius turns at the corners. 
 
 Registers. Specify height above floor, nominal size of 
 register, method of fitting in wall, the finish of the regis- 
 ter and whether fitted with shutters or not. 
 
 Protection and Covering. Specify kind and quality of pipe 
 covering and the finish of the surface of the covering. State 
 the amount of space between heating pipes and unprotected 
 woodwork. Distinguish between pipes that are to be covered 
 and those that are to be painted. All radiators and piping 
 not covered should be painted with two coats of .... bronze 
 or other finish acceptable to the superintendent. 
 
 Completion. Require all rubbish removed from the build- 
 ing and immediate grounds and deposited at a definite place. 
 
APPENDIX 
 
TABLE 1. 
 Squares, Cubes, Sq. Roots, Cube Roots, Circles. 
 
 No. 
 Diain. 
 
 Square 
 
 Cube 
 
 Sq. 
 Root 
 
 Cube 
 Root 
 
 Circle 
 
 Oircumf Area 
 
 .1 
 
 .010 
 
 .001 
 
 .310 
 
 .464 
 
 .314 
 
 .00785 
 
 .2 
 
 .040 
 
 .008 
 
 .447 
 
 .585 
 
 .628 
 
 .03146 
 
 .3 
 
 .090 
 
 .027 
 
 .548 
 
 .669 
 
 ,.942 
 
 .07008 
 
 .4 
 
 .160 
 
 .064 
 
 .633 
 
 .737 
 
 1.257 
 
 .12566 
 
 .5 
 
 .250 
 
 .125 
 
 .707 
 
 ..794 
 
 1.57CT 
 
 .19635 
 
 .6 
 
 .360 
 
 .216 
 
 .775 
 
 .843 
 
 1.885 
 
 .28274 
 
 .7 
 
 .490 
 
 .343 
 
 .837 
 
 .888 
 
 2.200 
 
 .38485 
 
 .8 
 
 .640 
 
 .512 
 
 .894 
 
 .928 
 
 2.513 
 
 .50260 
 
 .9 
 
 .810 
 
 .729 
 
 .949 
 
 (.965 
 
 2.830 
 
 .63620 
 
 1.0 
 
 1.000 
 
 1.000 
 
 .000 
 
 1.000 
 
 3.1416 
 
 .7854 
 
 1.1 
 
 1.210 
 
 1.331 
 
 .0488 
 
 1.0323 
 
 3.456 
 
 .9503 
 
 1.2 
 
 1.440 
 
 1.730 
 
 .0955 
 
 1.0627 
 
 3.770 
 
 1.1310 
 
 1.3 
 
 1.690 
 
 2.197 
 
 .1402 
 
 1.0914 
 
 4.084 
 
 1.3273 
 
 1.4 
 
 1.960 
 
 2.744 
 
 .1832 
 
 1.1187 
 
 4.398 
 
 1.5394 
 
 1.5 
 
 2.250 
 
 3.375 
 
 1.2247 
 
 1.1447 
 
 4.712 
 
 1.7672 
 
 1.8 
 
 2.560 
 
 4.096 
 
 1.2649 
 
 1.1696 
 
 5.027 
 
 2.0106 
 
 1.7 
 
 2.890 
 
 4.913 
 
 1.3038 
 
 1.1935 
 
 5.341 
 
 2.2698 
 
 1.8 
 
 3.240 
 
 5.832 
 
 1.3416 
 
 1.2164 
 
 5.655 
 
 2.5447 
 
 1.9 
 
 3.610 
 
 6.859 
 
 1.3784 
 
 1.2386 
 
 5.969 
 
 2.8353 
 
 2.0 
 
 4.000 
 
 8.000 
 
 1.4142 
 
 1.2599 
 
 6.283 
 
 3.1416 
 
 2.1 
 
 4.410 
 
 9.261 
 
 1.4491 
 
 1.2806 
 
 6.597 
 
 3.4630 
 
 2.2 
 
 4.840 
 
 10.648 
 
 1.483$ 
 
 1.3006 
 
 6.912 
 
 3.8013 
 
 2.3 
 
 5.290 
 
 12.167 
 
 1.5166 
 
 1.3200 
 
 7.226 
 
 4.1548 
 
 2.4 
 
 5.760 
 
 13.824 
 
 1.5493 
 
 1.3389 
 
 7.540 
 
 4.5239 
 
 2.5 
 
 6.250 
 
 15.625 
 
 1.5811 
 
 1.3572 
 
 7.854 
 
 4.9087 
 
 2.6 
 
 6.760 
 
 17.579 
 
 1.6125 
 
 1.3751 
 
 8.168 
 
 5.3093 
 
 2.7 
 
 7.290 
 
 19.683 
 
 1.6432 
 
 1.3925 
 
 8.482 
 
 5.7250 
 
 2.8 
 
 7.840 
 
 21.952 
 
 1.6733 
 
 1.4095 
 
 8.797 
 
 6.1575 
 
 2.9 
 
 8.410 
 
 24.389 
 
 1.7029 
 
 1.4260 
 
 9.111 
 
 6.6052 
 
 3.0 
 
 9.000 
 
 27.000 
 
 1.7321 
 
 .4422 
 
 9.425 
 
 7.0688 
 
 3.1 
 
 9.610 
 
 29.791 
 
 1.7607 
 
 .4581 
 
 9.739 
 
 7.5477 
 
 3.2 
 
 10.240 
 
 32.768 
 
 1.7889 
 
 .4736 
 
 10.053 
 
 8.0425 
 
 3.3 
 
 10.890 
 
 35.937 
 
 1.8166 
 
 .4888 
 
 10.367 
 
 8.5530 
 
 3.4 
 
 11.560 
 
 39.304 
 
 1.8439 
 
 .5037 
 
 10.681 
 
 9.0792 
 
 3.5 
 
 12.250 
 
 42.875 
 
 1.8708 
 
 1.5183 
 
 10.996 
 
 9.6211 
 
 3.6 
 
 12.960 
 
 46.656 
 
 1.8974 
 
 1.5326 
 
 11.310 
 
 10.179 
 
 3.7 
 
 13.690 
 
 50.653 
 
 1.9235 
 
 1.5467 
 
 11.624 
 
 10.752 
 
 3.8 
 
 14.440 
 
 54.872 
 
 1.9494 
 
 1.5605 
 
 11.938 
 
 11.341 
 
 3.9 
 
 15.210 
 
 59.319 
 
 1.9748 
 
 1.5741 
 
 12.262 
 
 11.946 
 
 4.0 
 
 16.000 
 
 64.000 
 
 2.0000 
 
 1.5870 
 
 12.566 
 
 12.566 
 
 4.1 
 
 16.810 
 
 68.921 
 
 2.0249 
 
 1.6005 
 
 12.881 
 
 13.203 
 
 4.2 
 
 17.640 
 
 74.088 
 
 2.0494 
 
 1.6134 
 
 13.195 
 
 13.854 
 
 4.3 
 
 18.490 
 
 79.507 
 
 2.0736 
 
 1.6261 
 
 13.500 
 
 14.522 
 
 4.4 
 
 19.360 
 
 85.184 ) 
 
 2.0976 . 
 
 1.6380 
 
 13.823 
 
 15.205 
 
 272 
 
Xo. 
 
 Diam 
 
 Square 
 
 Cube 
 
 Sq. 
 Boot 
 
 Cube 
 Root 
 
 Circle 
 
 Oircumf 
 
 Area 
 
 4.5 
 
 20.250 
 
 91.125 
 
 2.1213 
 
 1.6510 
 
 14.137 
 
 15.904 
 
 4.6 
 
 21.160 
 
 97.336 
 
 2.1448 
 
 1.6631 
 
 14.451 
 
 16.619 
 
 4.7 
 
 22.090 
 
 103.823 
 
 2.1680 
 
 1.6751 
 
 14.765 
 
 17.349 
 
 4.8 
 
 23.040 
 
 110.592 
 
 2.1909 
 
 1.6869 
 
 15.080 
 
 18.096 
 
 4.9 
 
 24.010 
 
 117.649 
 
 2.2136 
 
 1.6983 
 
 15.394 
 
 18.859 
 
 5.0 
 
 25.000 
 
 125.000 
 
 2.2361 
 
 1.7100 
 
 15.708 
 
 19.635 
 
 5.1 
 
 26.010 
 
 132.651 
 
 2.2583 
 
 1.7213 
 
 16.022 
 
 20.428 
 
 5.2 
 
 27.040 
 
 140.608 
 
 2.2804 
 
 1.7325 
 
 16.336 
 
 21.237 
 
 5.3 
 
 28.090 
 
 148.877 
 
 2.3022 
 
 1.7435 
 
 16.650 
 
 22.062 
 
 5.4 
 
 29.160 
 
 157.464 
 
 2.3238 
 
 1.7544 
 
 16.965 
 
 22.902 
 
 5.5 
 
 30.250 
 
 16S.375 
 
 2.3452 
 
 1.7653 
 
 17.279 
 
 23.758 
 
 5.6 
 
 31.360 
 
 175.616 
 
 2.3664 
 
 1.7760 
 
 17.593 
 
 24.630 
 
 5.7 
 
 32.490 
 
 185.193 
 
 2.3875 
 
 1.7863 
 
 17.907 
 
 25.518 
 
 5.8 
 
 33.640 
 
 195.112 
 
 2.4083 
 
 1.7967 
 
 18.221 
 
 26.421 
 
 5.9 
 
 34.810 
 
 205.379 
 
 2.4290 
 
 1.8070 
 
 18.536 
 
 27.340 
 
 6.0 
 
 36.000 
 
 216.000 
 
 2.4495 
 
 1.8171 
 
 18.850 
 
 28.274 
 
 6.1 
 
 37.210 
 
 226.981 
 
 2.4698 
 
 1.8272 
 
 19.164 
 
 29.225 
 
 6.3 
 
 38.440 
 
 238.328 
 
 2.4900 
 
 1.8371 
 
 19.478 
 
 30.191 
 
 6.3 
 
 39.690 
 
 250.047 
 
 2.5100 
 
 1.8469 
 
 19.792 
 
 31.173 
 
 6.4 
 
 40.960 
 
 262.144 
 
 2.5298 
 
 1.8566 
 
 20.106 
 
 32.170 
 
 6.5 
 
 42.250 
 
 274.625 
 
 2.5495 
 
 1.8663 
 
 20.420 
 
 33.183 
 
 6.6 
 
 43.560 
 
 287.496 
 
 2.5691 
 
 1.8758 
 
 20.735 
 
 34.212 
 
 - 6.7 
 
 44.890 
 
 300.763 
 
 2.5884 
 
 1.8852 
 
 21.049 
 
 35.257 
 
 6.8 
 
 46.240 
 
 314.432 
 
 2.6077 
 
 1.8945 
 
 21.363 
 
 36.317 
 
 6.9 
 
 47.610 
 
 328.509 
 
 2.6268 
 
 1.9088 
 
 21.677 
 
 37.393 
 
 7.0 
 
 49.000 
 
 343.000 
 
 2.6458 
 
 1.9129 
 
 21.931 
 
 38.485 
 
 7.1 
 
 50.410 
 
 357.911 
 
 2.6646 
 
 1.9220 
 
 22.305 
 
 39.592 
 
 7.2 
 
 51.840 
 
 373.248 
 
 2.6833 
 
 1.9310 
 
 22.619 
 
 40.715 
 
 7.3 
 
 53.290 
 
 389.017 
 
 2.7019 
 
 1.9399 
 
 22.934 
 
 41.854 
 
 7.4 
 
 54.760 
 
 405.224 
 
 2.7203 
 
 1.9487 
 
 23.248 
 
 43.008 
 
 7.5 
 
 56.250 
 
 421.875 
 
 2.7386 
 
 1.9574 
 
 23.562 
 
 44.179 
 
 7.6 
 
 57.760 
 
 438.976 
 
 2.7568 
 
 1.9661 
 
 23.876 
 
 45.365 
 
 7.7 
 
 59.290 
 
 456.533 
 
 2.7749 
 
 1.9747 
 
 24.190 
 
 46.566 
 
 7.8 
 
 60.840 
 
 474.552 
 
 2.7929 
 
 1.9832 
 
 24.504 
 
 47.784 
 
 7.9 
 
 62.410 
 
 493.039 
 
 2.8107 
 
 1.9916 
 
 24.819 
 
 49.017 
 
 8.0 
 
 64.000 
 
 512.000 
 
 2.8284 
 
 2.0000 
 
 25.133 
 
 50.266 
 
 8.1 
 
 65.610 
 
 531.441 
 
 2.8461 
 
 2.CC83 
 
 25.447 
 
 51.530 
 
 8.2 
 
 67.240 
 
 551.468 
 
 2.8636 
 
 2.0165 
 
 25.761 
 
 53.810 
 
 8.3 
 
 68.890 
 
 571.787 
 
 2.8810 
 
 2.0247 
 
 26.075 
 
 54.103 
 
 8.4 
 
 70.560 
 
 592.704 
 
 2.8983 
 
 2.0328 
 
 26.389 
 
 55.418 
 
 8.5 
 
 72.250 
 
 614.125 
 
 2.9155 
 
 2.0408 
 
 26.704 
 
 58.745 
 
 8.6 
 
 73.960 
 
 636.056 
 
 2.9326' 
 
 2.0488 
 
 27.018 
 
 58.083 
 
 8.7 
 
 75.690 
 
 658.503 
 
 2.9496 
 
 2.0567 
 
 27.332 
 
 59.447 
 
 8.8 
 
 77.440 
 
 681.473 
 
 2.9665 
 
 2.0646 
 
 27.646 
 
 60.821 
 
 8.9 
 
 79.210 
 
 704.969 
 
 2.9833 
 
 2.0724 
 
 27.960 
 
 62.211 
 
 273 
 

 
 
 
 
 Circle 
 
 No. 
 
 Diam. 
 
 Square 
 
 Cube 
 
 Sq. 
 Root 
 
 Cube 
 Root 
 
 
 Oircumf 
 
 Area 
 
 9.0 
 
 81.000 
 
 729.000 
 
 3.0000 
 
 2.0801 
 
 28.274 
 
 63.617 
 
 9.1 
 
 82.810 
 
 753.571 
 
 3.0166 
 
 2.0878 
 
 28.588 
 
 65.039 
 
 9.3 
 
 84.640 
 
 778.685 
 
 3.0332 
 
 2.0954 
 
 28.903 
 
 66.476 
 
 9.3 
 
 86.490 
 
 804.357 
 
 3.0496 
 
 2.1029 
 
 29.217 
 
 67.929 
 
 9.4 
 
 88.360 
 
 830.584 
 
 3.0659 
 
 2.1105 
 
 29.531 
 
 69.398 
 
 9.5 
 
 90.250 
 
 857.375 
 
 3.0822 
 
 2.1179 
 
 29.845 
 
 70.882 
 
 9.6 
 
 92.160 
 
 884.736 
 
 3.0984 
 
 2.1253 
 
 30.159 
 
 72.383 
 
 9.7 
 
 94.090 
 
 912.673 
 
 3.1145 
 
 2.1327 
 
 30.473 
 
 73.898 
 
 9.8 
 
 96.040 
 
 941.198 
 
 3.1305 
 
 2.1400 
 
 30.788 
 
 75.430 
 
 9.9 
 
 98.010 
 
 970.299 
 
 3.1464 
 
 2.1472 
 
 31.102 
 
 76.977 
 
 10 
 
 100.000 
 
 1000.000 
 
 3.1623 
 
 2.1544 
 
 31.416 
 
 78.540 
 
 11 
 
 121.000 
 
 1331.000 
 
 3.3166 
 
 2.2239 
 
 34.558 
 
 95.033 
 
 12 
 
 144. COO 
 
 1728.000 
 
 3.4641 
 
 2.2894 
 
 37.699 
 
 113.097 
 
 IS 
 
 169.000 
 
 2197.000 
 
 3.6056 
 
 2.3513 
 
 40.841 
 
 132.732 
 
 14 
 
 196.000 
 
 2744.000 
 
 3.7417 
 
 2.4101 
 
 43.983 
 
 153.938 
 
 15 
 
 225.000 
 
 3375.000 
 
 3.8730 
 
 2.4662 
 
 47.124 
 
 176.715 
 
 16 
 
 256.000 
 
 4096.000 
 
 4.0000 
 
 2.5198 
 
 50.265 
 
 201.062 
 
 17 
 
 289. 000 
 
 4913.000 
 
 4.1231 
 
 2.5713 
 
 53.407 
 
 226.980 
 
 18 
 
 324.000 
 
 5832.000 
 
 4.2426 
 
 2.6207 
 
 56.549 
 
 254.469 
 
 19 
 
 361.000 
 
 6859.000 
 
 4.3589 
 
 2.6684 
 
 59.690 
 
 283.529 
 
 20 
 
 400.000 
 
 8000.000 
 
 4.4721 
 
 2.7144 
 
 62.832 
 
 314.159 
 
 21 
 
 441.000 
 
 9261.000 
 
 4.5826 
 
 2.7589 
 
 65.973 
 
 346.361 
 
 23 
 
 484.000 
 
 10648.000 
 
 4.6904 
 
 2.8021 
 
 69.115 
 
 380.133 
 
 23 
 
 529.000 
 
 12167.000 
 
 4.7958 
 
 2.8439 
 
 72.257 
 
 415.476 
 
 24 
 
 576.000 
 
 13824.000 
 
 4.8990 
 
 2.8845 
 
 75.398 
 
 452.389 
 
 25 
 
 625.000 
 
 15625.000 
 
 5.0000 
 
 2.9241 
 
 78.540 
 
 490.874 
 
 38 
 
 676.000 
 
 17576.000 
 
 5.0990 
 
 2.9625 
 
 81.681 
 
 530.929 
 
 27 
 
 729.000 
 
 19683.000 
 
 5.1962 
 
 3.0000 
 
 84.823 
 
 572.555 
 
 28 
 
 784.000 
 
 21952.000 
 
 5.2915 
 
 3.0366 
 
 87.966 
 
 615.752 
 
 29 
 
 841.000 
 
 24389.000 
 
 5.3852 
 
 3.0723 
 
 91.106 
 
 660.520 
 
 30 
 
 900.000 
 
 27000.000 
 
 5.4772 
 
 3.1072 
 
 94.248 
 
 706.858 
 
 31 
 
 961.000 
 
 29791.000 
 
 5.5678 
 
 3.1414 
 
 97.389 
 
 754.763 
 
 33 
 
 1024.000 
 
 32768.000 
 
 5.6569 
 
 3.1748 
 
 100.531 
 
 804.248 
 
 33 
 
 1089.000 
 
 35937.000 
 
 5.7446 
 
 3.2075 
 
 103.673 
 
 855.299 
 
 34 
 
 1156.000 
 
 39304.000 
 
 5.8310 
 
 3.2396 
 
 106.841 
 
 907.920 
 
 35 
 
 1225.000 
 
 42875.000 
 
 5.9161 
 
 3.2710 
 
 109.956 
 
 962.113 
 
 36 
 
 1296.000 
 
 46656.000 
 
 6.0000 
 
 3.3019 
 
 113.097 
 
 1017.88 
 
 37 
 
 1369.000 
 
 50653.000 
 
 6.0827 
 
 3.3322 
 
 116.239 
 
 1075-31 
 
 38 
 
 1444.000 
 
 54872.000 
 
 6.1644 
 
 3.3620 
 
 119.381 
 
 1134.11 
 
 39 
 
 1521.000 
 
 59319.000 
 
 6.2450 
 
 3.3912 
 
 122.522 
 
 1194.59 
 
 40 
 
 1600.000 
 
 640CO.OOO 
 
 6.3246 
 
 3.4200 
 
 125.66 
 
 1256.64 
 
 41 
 
 1681.000 
 
 68921.0001 
 
 6.4031 
 
 3.4482 
 
 128.81 
 
 1320.25 
 
 42 
 
 1764.000 
 
 74088. OOO 1 
 
 6.4807 
 
 3.4760 
 
 131.95 
 
 1385.44 
 
 43 
 
 1849.000 
 
 79507.000 
 
 6.5574 
 
 3.5084 
 
 135.09 
 
 1452.20 
 
 44 
 
 1936.000 
 
 85184.000 
 
 6.6333 
 
 3.5303 
 
 138.23 
 
 1520.58 
 
 274 
 
No. 
 Diam. 
 
 Square 
 
 Cube 
 
 Sq. 
 Root 
 
 Cube 
 Root 
 
 Circle 
 
 Dircumf 
 
 Area 
 
 45 
 
 2025.000 
 
 91125.000 
 
 6.7082 
 
 3.5569 
 
 141.37 
 
 1590.43 
 
 46 
 
 2116.000 
 
 97336.000 
 
 6.7823 
 
 3.5830 
 
 144.51 
 
 1661.90 
 
 47 
 
 2209.000 
 
 103823.000 
 
 6.8557 
 
 3.6088 
 
 147.65 
 
 1734.94 
 
 48 
 
 2304.000 
 
 110592.000 
 
 6.9282 
 
 3.6342 
 
 150.80 
 
 18C9.56 
 
 49 
 
 2401.000 
 
 117649.000 
 
 7.0000 
 
 3.6593 
 
 153.94 
 
 1885.74 
 
 60 
 
 2500.000 
 
 125000.000 
 
 7.0711 
 
 3.6840 
 
 157.08 
 
 1963-50 
 
 51 
 
 2601.000 
 
 132651.000 
 
 7.1414 
 
 3.7084 
 
 160.22 
 
 2042.82 
 
 53 
 
 2704.000 
 
 140608.000 
 
 7.2111 
 
 3.7325 
 
 163.36 
 
 2123.72 
 
 53 
 
 2809.000 
 
 148877.000 
 
 7.2801 
 
 3.7563 
 
 166.50 
 
 2206.18 
 
 54 
 
 2916.000 
 
 157464.000 
 
 7.3485 
 
 3.7798 
 
 169.65 
 
 2290.22 
 
 55 
 
 3025.000 
 
 166375.000 
 
 7.4162 
 
 3.8030 
 
 172.79 
 
 2375.83 
 
 56 
 
 3136.000 
 
 175616.000 
 
 7.4833 
 
 3.8259 
 
 175.93 
 
 2463.01 
 
 57 
 
 3249.000 
 
 185193.000 
 
 7.5498 
 
 3.8485 
 
 179.07 
 
 2551.76 
 
 58 
 
 S364.000 
 
 195112.000 
 
 7.6158 
 
 3.8709 
 
 182.21 
 
 2642.08 
 
 59 
 
 3481.000 
 
 205379.000 
 
 7.6811 
 
 3.8930 
 
 185.35 
 
 2733.97 
 
 60 
 
 3600.000 
 
 216000.000 
 
 7.7460 
 
 3.9149 
 
 188.50 
 
 2827.43 
 
 61 
 
 3721.000 
 
 226981.000 
 
 7.8102 
 
 3.9365 
 
 191.64 
 
 2922.47 
 
 62 
 
 844.000 
 
 238328.000 
 
 7.8740 
 
 3.9579 
 
 194.78 
 
 3019.07 
 
 63 
 
 3969.000 
 
 250047.000 
 
 7.9373 
 
 3.9791 
 
 197.92 
 
 3117.25 
 
 64 
 
 4096.000 
 
 262144.000 
 
 8.0000 
 
 4.0000 
 
 201.06 
 
 3216.99 
 
 65 
 
 4225.000 
 
 274625.000 
 
 8.0623 
 
 4.0207 
 
 204.20 
 
 3318.31 
 
 66 
 
 4356.000 
 
 287496.000 
 
 8.1240 
 
 4.0412 
 
 207.34 
 
 3421.19 
 
 67 
 
 4489.000 
 
 300763.000 
 
 8.1854 
 
 4.0615 
 
 210.49 
 
 3525.65 
 
 68 
 
 4624.000 
 
 314432.000 
 
 8.2462 
 
 4.0817 
 
 213.63 
 
 3631.68 
 
 69 
 
 4761.000 
 
 328509.000 
 
 8.3086 
 
 4.1016 
 
 216.77 
 
 3739.28 
 
 70 
 
 4900.000 
 
 343000.000 
 
 8.3666 
 
 4.1213 
 
 219.91 
 
 3848.45 
 
 71 
 
 5041.000 
 
 357911.000 
 
 8.4261 
 
 4.1408 
 
 223.05 
 
 3959.19 
 
 72 
 
 5184.000 
 
 373248.000 
 
 8.4853 
 
 4.1602 
 
 226.19 
 
 4071.50 
 
 73 
 
 5329.000 
 
 389017.000 
 
 8.5440 
 
 4.1793 
 
 229.34 
 
 4185.39 
 
 74 
 
 5476.000 
 
 405224.000 
 
 8.6023 
 
 4.1983 
 
 232.48 
 
 4300.84 
 
 75 
 
 5625.000 
 
 421875.000 
 
 8.6603 
 
 4.2172 
 
 235.62 
 
 4417.86 
 
 76 
 
 5776.000 
 
 438976.000 
 
 8.7178 
 
 4.2358 
 
 238.76 
 
 4536.46 
 
 77 
 
 5929.000 
 
 456533.000 
 
 8.7750 
 
 4.2543 
 
 241.90 
 
 4656.63 
 
 78 
 
 6084.000 
 
 474552.000 
 
 8.8318 
 
 4.2727 
 
 245.04 
 
 4778.36 
 
 79 
 
 6241.000 
 
 493039.000 
 
 8.8882 
 
 4.2908 
 
 248.19 
 
 4901.67 
 
 80 
 
 6400.000 
 
 512000.000 
 
 8.9443 
 
 4.3089 
 
 251.33 
 
 5026.55 
 
 81 
 
 6561.000 
 
 531441.000 
 
 9.0000 
 
 4.3267 
 
 254.47 
 
 5153.00 
 
 82 
 
 6724.000 
 
 551368.000 
 
 9.0554 
 
 4.3445 
 
 257.61 
 
 5281.03 
 
 83 
 
 6889.000 
 
 571787.000 
 
 9.1104 
 
 4.3621 
 
 260.75 
 
 5410.61 
 
 84 
 
 7056.000 
 
 592704.000 
 
 9.1652 
 
 4.3795 
 
 263.89 
 
 5541.77 
 
 85 
 
 7225.000 
 
 614125.000 
 
 9.2195 
 
 4.3968 
 
 267.04 
 
 5674.50 
 
 86 
 
 7396.000 
 
 636056.000 
 
 9.2736 
 
 4.4140 
 
 270.18 
 
 5808.80 
 
 87 
 
 7569.000 
 
 658503.000 
 
 9.3274 
 
 4.4310 
 
 273.32 
 
 6944.68 
 
 88 
 
 7744.000 
 
 681472.000 
 
 9.3808 
 
 4.4480 
 
 276.46 
 
 6082.12 
 
 89 
 
 7921.000 
 
 704969.000 
 
 9.4340 
 
 4.4647 
 
 279.60 
 
 6221.14 
 
 275 
 
No. 
 Diam. 
 
 Square 
 
 Cube 
 
 Sq. 
 Root 
 
 Cube 
 Root 
 
 Circle 
 
 Oircumf Area 
 
 90 
 
 8100.000 
 
 729000.000 
 
 9.4868 
 
 4.4814 
 
 282.74 
 
 6361.73 
 
 91 
 
 8281.000 
 
 753571.000 
 
 9.5394 
 
 4.4979 
 
 285.88 
 
 6503.88 
 
 92 
 
 8464.000 
 
 778688.000 
 
 9.5917 
 
 4.5144 
 
 289.03 
 
 6647.61 
 
 93 
 
 8649.000 
 
 804357.000 
 
 9.6437 
 
 4.5307 
 
 292.17 
 
 6792.91 
 
 94 
 
 8836.000 
 
 830584.000 
 
 9.6954 
 
 4.5468 
 
 295.31 
 
 6939.78 
 
 95 
 
 9025.000 
 
 857375.000 
 
 9.7468 
 
 4.5629 
 
 298.45 
 
 7088.22 
 
 99 
 
 9216.000 
 
 884736.000 
 
 9.7980 
 
 4.5789 
 
 301.59 
 
 7238.23 
 
 97 
 
 9409.000 
 
 912673.000 
 
 9.8489 
 
 4.5947 
 
 30i.73 
 
 - 7389.81 
 
 98 
 
 9604.000 
 
 941192.000 
 
 9.8995 
 
 4.6104 
 
 307.88 
 
 7542.96 
 
 99 
 
 9801.000 
 
 970299.000 
 
 9.9499 
 
 4.6261 
 
 311.02 
 
 7697.69 
 
 100 
 
 10000.000 
 
 1000000. 000 
 
 10.0000 
 
 4.6416 
 
 314.16 
 
 7853.98 
 
 105 
 
 11025.000 
 
 1157625.000 
 
 10.2470 
 
 4.7177 
 
 329.87 
 
 8659.01 
 
 110 
 
 12100.000 
 
 1331000.000 
 
 10.4881 
 
 4.7914 
 
 345.58 
 
 9503.32 
 
 115 
 
 13225.000 
 
 1520875.000 
 
 10.7238 
 
 4.8629 
 
 361.28 
 
 10388.89 
 
 120 
 
 14400.000 
 
 1728COO.OOO 
 
 10.9545 
 
 4.9324 
 
 376.99 
 
 11309.73 
 
 125 
 
 15625.000 
 
 1953125.000 
 
 11.1803 
 
 5.0000 
 
 392.70 
 
 12271.85 
 
 130 
 
 16900.000 
 
 2197000.000 
 
 11.4018 
 
 5.0658 
 
 408.41 
 
 13273.23 
 
 135 
 
 18225.000 
 
 2460375.000 
 
 11.6190 
 
 5.1299 
 
 424.12 
 
 14313.88 
 
 140 
 
 19600.000 
 
 2744000.000 
 
 11.8322 
 
 5.1925 
 
 439.82 
 
 15393.80 
 
 145> 
 
 2102-5.000 
 
 3048625.000 
 
 12.0416 
 
 5.2536 
 
 455.53 
 
 16513.00 
 
 150 
 
 22500.000 
 
 3375000.000 
 
 12.2474 
 
 5.3133 
 
 471.24 
 
 17671.46 
 
 155 
 
 24025.000 
 
 3723875.000 
 
 12.4499 
 
 5.3717 
 
 486.95 
 
 18869.19 
 
 160 
 
 25600.000 
 
 4096000.000 
 
 12.6491 
 
 5.4288 
 
 502.65 
 
 20106.19 
 
 165 
 
 27225.000 
 
 4493125.000 
 
 12.8452 
 
 5.4848 
 
 518.36 
 
 21382.46 
 
 170 
 
 28900.000 
 
 4913000.000 
 
 13.0384 
 
 5.5397 
 
 534.07 
 
 22698.01 
 
 175 
 
 30625.000 
 
 359375.000 
 
 13.2288 
 
 5.5934 
 
 549.78 
 
 24052.82 
 
 180 
 
 32400.000 
 
 5832000.000 
 
 13.4164 
 
 5.6462 
 
 565.49 
 
 25446.90 
 
 185 
 
 3-1225.000 
 
 6331625.000 
 
 13.6015 
 
 5.6980 
 
 581.19 
 
 26880.25 
 
 190 
 
 36100.000 
 
 6859000.000 
 
 13.7840 
 
 5.7489 
 
 596.90 
 
 28352.87 
 
 195 
 
 38025.000 
 
 7414875.000 
 
 13.9642 
 
 5.7989 
 
 612.61 
 
 29864.77 
 
 200 
 
 40000.000 
 
 8000000.000 
 
 14.1421 
 
 5.8480 
 
 628.32 
 
 31415.93 
 
 205 
 
 42025.000 
 
 8615125.000 
 
 14.3178 
 
 5.8964 
 
 644.03 
 
 33006.36 
 
 210 
 
 44100.000 
 
 9261000.000 
 
 14.4914 
 
 5.9439 
 
 659.73 
 
 34636.06 
 
 215 
 
 46225.000 
 
 9938375.000 
 
 14.6629 
 
 5.9907 
 
 675.44 
 
 36305.03 
 
 230 
 
 48400.000 
 
 10648000.000 
 
 14.8324 
 
 6.0368 
 
 691.15 
 
 38013.27 
 
 225 
 
 50625.000 
 
 11390625.000 
 
 15.0000 
 
 6.0822 
 
 706.86 
 
 39760.78 
 
 230 
 
 52900.000 
 
 12167000.000 
 
 15.1658 
 
 6.1269 
 
 722.57 
 
 41547.56 
 
 235 
 
 55225.000 
 
 12977875.000 
 
 15.3297 
 
 6.1710 
 
 738.27 
 
 43373.61 
 
 240 
 
 57600.000 
 
 13824000.000 
 
 15.4919 
 
 6.2145 
 
 753.98 
 
 45238.93 
 
 245 
 
 60025.000 
 
 14706125.000 
 
 15.6525 
 
 6.2573 
 
 769.69 
 
 47143.52 
 
 350 
 
 62500.000 
 
 15625000.000 
 
 15.8114 
 
 6.2996 
 
 785.40 
 
 49087.39 
 
 255 
 
 65025.000 
 
 16581375.000 
 
 15.9687 
 
 6.3413 
 
 801.11 
 
 51070.52 
 
 260 
 
 67600.000 
 
 17576000.000 
 
 16.1245 
 
 6.3825 
 
 816.81 
 
 53092.92 
 
 265 
 
 70225.000 
 
 18609625.000 
 
 16.2788 
 
 6.4232 
 
 832.52 
 
 55154.59 
 
 270 
 
 72900.000 
 
 19683000.000 
 
 16.4317 
 
 6.4633 
 
 848.23 
 
 67255.63 
 
 276 
 
No, 
 Diam. 
 
 Square 
 
 Cube 
 
 Sq. 
 Boot 
 
 Cube 
 Root 
 
 Circle 
 
 Oircumf 
 
 Area 
 
 275 
 
 75625.000 
 
 20796875.000 
 
 16.5831 
 
 6.5030 
 
 863.94 
 
 59395.74 
 
 280 
 
 78400.000 
 
 21952000.000 
 
 16.7332 
 
 6.5421 
 
 879.65 
 
 01575.28 
 
 285 
 
 81225.000 
 
 23149125.000 
 
 16.8819 
 
 6.5808 
 
 895.35 
 
 63793.97 
 
 290 
 
 84100.000 
 
 24389000.000 
 
 17.0294 
 
 6.6191 
 
 911.00 
 
 66051.99 
 
 295 
 
 87025.000 
 
 25672375.000 
 
 17.1756 
 
 0.6569 
 
 926.77 
 
 08349.28 
 
 800 
 
 90000.000 
 
 27000000.000 
 
 17.3205 
 
 6.6943 
 
 942.48 
 
 70085.83 
 
 305 
 
 93025.000 
 
 28372625.000 
 
 17.4642 
 
 6.7313 
 
 958.19 
 
 73061.66 
 
 310 
 
 96100.000 
 
 29791000.000 
 
 17.6068 
 
 6.7679 
 
 973.89 
 
 75476.76 
 
 315 
 
 99225.000 
 
 31255875.000 
 
 17.74821 
 
 6.8041 
 
 989.60 
 
 77931.13 
 
 320 
 
 102400.000 
 
 32768000.000 
 
 17.8885 
 
 6.8399 
 
 1005.31 
 
 80424.77 
 
 325 
 
 105625.000 
 
 34328125.000 
 
 18.0278 
 
 6.8753 
 
 1021.021 
 
 82957.68 
 
 330 
 
 108900.000 
 
 35937000.000 
 
 18.1659 
 
 6.9104 
 
 1036.73 
 
 85529.86 
 
 335 
 
 112225.000 
 
 37595375.000 
 
 18.3030 
 
 6.9451 
 
 1052.43 
 
 88141.31 
 
 340 
 
 115600.000 
 
 39304000.000 
 
 18.4391 
 
 6.9795 
 
 1068.14 
 
 90792.03 
 
 345 
 
 119025.000 
 
 41063625.000 
 
 18.5742 
 
 7.0130 
 
 1083.85 
 
 93482.00 
 
 350 
 
 122500.000 
 
 42875000.000 
 
 18.7063 
 
 7.0473 
 
 1099.50 
 
 96211.28 
 
 355 
 
 126025.000 
 
 44738875.000 
 
 18.8414 
 
 7.0807 
 
 1115.27 
 
 98979.80 
 
 360 
 
 129600.000 
 
 46656000.000 
 
 18.9737 
 
 7.1138 
 
 1130.97 
 
 101787.60 
 
 365 
 
 133225.000 
 
 48627125.000 
 
 19.1050 
 
 7.1460 
 
 1140.68 
 
 104034.67 
 
 370 
 
 136900.000 
 
 50653000.000 
 
 19.2354 
 
 7.1791 
 
 1162.39 
 
 107521.01 
 
 375 
 
 140625.000 
 
 52734375.000 
 
 19.3649 
 
 7.2112 
 
 1178.10 
 
 110440.62 
 
 380 
 
 144400.000 
 
 54872000.000 
 
 19.4936 
 
 7.2432 
 
 1193.81 
 
 113411.49 
 
 385 
 
 148225.000 
 
 57066625.000 
 
 19.6214 
 
 7.2748 
 
 1209.51 
 
 116415.64 
 
 390 
 
 152100.000 
 
 59319000.000 
 
 19.7484 
 
 7.3061 
 
 1225.22 
 
 119459.06 
 
 395 
 
 156025.000 
 
 61629875.000 
 
 19.8746 
 
 7.3372 
 
 1240.93 
 
 122541.75 
 
 400 
 
 160000.000 
 
 64000000.000 
 
 20.0000 
 
 7.3681 
 
 1256.64 
 
 125663.71 
 
 405 
 
 164025.000 
 
 66430125.000 
 
 20.1246 
 
 7.3980 
 
 1272.35 
 
 123824.93 
 
 410 
 
 168100.000 
 
 68921000.000 
 
 20.2485 
 
 7.4290 
 
 1288.05 
 
 132025.43 
 
 415 
 
 172225.000 
 
 71473375.000 
 
 20.3715 
 
 7.4590 
 
 1303.76 
 
 135205.20 
 
 420 
 
 176400.000 
 
 74088000.000 
 
 20.4939 
 
 7.4889 
 
 1319.47 
 
 138544.24 
 
 425 
 
 180625.000 
 
 76765625.000 
 
 20.6155 
 
 7.5185 
 
 1335.18 
 
 141802.54 
 
 430 
 
 184900.000 
 
 79507000.000 
 
 20.7364 
 
 7.5478 
 
 1350.88 
 
 145220.12 
 
 435 
 
 189225.000 
 
 82312875.000 
 
 20.8567 
 
 7.5770 
 
 1306.59 
 
 148616.97 
 
 440 
 
 193600.000 
 
 85184000.000 
 
 20.9762 
 
 7.6059 
 
 1382.30 
 
 152053.08 
 
 445 
 
 198025.000 
 
 88121125.000 
 
 21.0950 
 
 7.6346 
 
 1398.01 
 
 155528.47 
 
 450 
 
 202500.000 
 
 91125000.000 
 
 21.2132 
 
 7.6631 
 
 1413.72 
 
 159043.13 
 
 455 
 
 207025.000 
 
 94196375.000 
 
 21.3307 
 
 7.6914 
 
 1429.42 
 
 162597.05 
 
 460 
 
 211600.000 
 
 97336000.000 
 
 21.4476 
 
 7.7194 
 
 1445.13 
 
 106190.25 
 
 465 
 
 216225.000 
 
 100544625.000 
 
 21.5639 
 
 7.7473 
 
 1400.84 
 
 169822.72 
 
 470 
 
 220900.000 
 
 103823000.000 
 
 21.6795 
 
 7.7750 
 
 1476.55 
 
 173494.45 
 
 475 
 
 225625.000 
 
 107171875.000 
 
 21.7945 
 
 7.o025 
 
 1492.20 
 
 177205.46 
 
 480 
 
 230400.000 
 
 110592000.000 
 
 21.9089 
 
 7.8297 
 
 1507.90 
 
 180955.74 
 
 485 
 
 235225.000 
 
 114084125.000 
 
 22.0227 
 
 7.8508 
 
 1523.67 
 
 184745.28 
 
 490 
 
 240100.000 
 
 117649000.000 
 
 22.1359 
 
 7.8837 
 
 1539.38 
 
 183574.10 
 
 495 
 
 245025.000 
 
 121287375.000 
 
 22.2486 
 
 7.9105 
 
 1555.09 
 
 192442.18 
 
 500 
 
 250000.000 
 
 125000000.000 
 
 22.3607 
 
 7.9370 
 
 1570.80 
 
 196349.54 
 
 277 
 
TABLE 2. 
 Properties of Saturated Steam.* 
 
 Absolute 
 press 're Ibs. 
 per sq. in. 
 
 Tempera- 
 ture 
 Degrees F. 
 
 Heat 
 of the 
 Liquid 
 
 Heat of the 
 Vaporiza- 
 tion 
 
 Total 
 Heat 
 Above 32 
 
 1 
 
 101.84 
 
 69.8 
 
 1034.7 
 
 1104.5 
 
 3 
 
 126.15 
 
 94.2 
 
 1021.9 
 
 1116.1 
 
 3 
 
 141.52 
 
 109.6 
 
 1012.2 
 
 1121.8 
 
 4 
 
 153.00 
 
 121.0 
 
 1005.5 
 
 1126.5 
 
 5 
 
 162.26 
 
 130.3 
 
 1000.0 
 
 1130.3 
 
 G 
 
 170.07 
 
 138.1 
 
 995.5 
 
 1133.6 
 
 7 
 
 176.84 
 
 144.9 
 
 991.4 
 
 - 1136.3 
 
 8 
 
 182.86 
 
 150.9 
 
 987.8 
 
 1138.7 
 
 9 
 
 188.27 
 
 156.4 
 
 984.5 
 
 1140.9 
 
 10 
 
 193.21 
 
 161.3 
 
 981.4 
 
 1142.7 
 
 11 
 
 197.74 
 
 165.9 
 
 978.6 
 
 1144.6 
 
 12 
 
 201.95 
 
 170.1 
 
 976.0 
 
 1146.1 
 
 13 
 
 205.87 
 
 174.1 
 
 973.6 
 
 1147.7 
 
 14 
 
 209.55 
 
 177.8 
 
 971.2 
 
 1149.0 
 
 14.7 
 
 212.00 
 
 180.3 
 
 969.7 
 
 1150.0 
 
 15 
 
 213.03 
 
 181.3 
 
 969.1 
 
 1150.4 
 
 16 
 
 216.31 
 
 184.6 
 
 967.0 
 
 1151.6 
 
 17 
 
 219.43 
 
 187.8 
 
 965.0 
 
 1152.8 
 
 18 
 
 222.40 
 
 190.8 
 
 963.1 
 
 1153.9 
 
 19 
 
 225.24 
 
 193.7 
 
 981.2 
 
 1154.9 
 
 20 
 
 227.95 
 
 196.4 
 
 059.4 
 
 1155.8 
 
 21 
 
 230.56 
 
 199.1 
 
 957.7 
 
 1156.8 
 
 22 
 
 233.07 
 
 201.6 
 
 956.0 
 
 1157.6 
 
 23 
 
 235.50 
 
 204.1 
 
 954.4 
 
 1158.5 
 
 84 
 
 237.82 
 
 206.4 
 
 952.9 
 
 1159.3 
 
 25 
 
 240.07 
 
 208.7 
 
 951.4 
 
 1160.1 
 
 26 
 
 242.26 
 
 210.9 
 
 949.9 
 
 1160.8 
 
 27 
 
 244.36 
 
 213.0 
 
 948.5 
 
 1161.5 
 
 28 
 
 246.41 
 
 215.1 
 
 947.1 
 
 1162.2 
 
 29 
 
 248.41 
 
 217.2 
 
 945.8 
 
 1163.0 
 
 60 
 
 250.34 
 
 219.1 
 
 944.4 
 
 1163.5 
 
 81 
 
 252.22 
 
 221.0 
 
 943.1 
 
 1164.1 
 
 82 
 
 254.05 
 
 222.9 
 
 941.8 
 
 1164.7 
 
 S3 
 
 255.84 
 
 224.7 
 
 940.6 
 
 1165.3 
 
 84 
 
 257.59 
 
 226.5 
 
 939.4 
 
 1165.9 
 
 35 
 
 259.29 
 
 228.2 
 
 938.3 
 
 1166.4 
 
 86 
 
 260.96 
 
 229.9 
 
 937.1 
 
 1167.0 
 
 87 
 
 262. 5K 
 
 231.6' 
 
 935.9 
 
 1167.5 
 
 38 
 
 264.17 
 
 233.2 
 
 934.8 
 
 1168.0 
 
 89 
 
 265.73 
 
 234.8 
 
 933.7 
 
 1168.6 
 
 40 
 
 267.20 
 
 236.4 
 
 932.6 
 
 1169.0 
 
 41 
 
 268.76 
 
 237.9 
 
 931.6 
 
 1169.6 
 
 42 
 
 270.23 
 
 239.4 
 
 930.6 
 
 1170.0 
 
 43 
 
 271.66 
 
 240.8 
 
 929.5 
 
 1170.3 
 
 44 
 
 273.07 
 
 242.3 
 
 928.5 
 
 1170.8 
 
 'Condensed from Peabody's Steam Tables. 
 278 
 
Absolute 
 press're Ibs. 
 per sq. in. 
 
 Tempera- 
 ture 
 Degrees F. 
 
 Heat 
 of the 
 Liquid 
 
 Heat of the 
 Vaporiza- 
 tion 
 
 Total 
 Heat 
 Above 32 
 
 45 
 
 274.46 
 
 243.7 
 
 927.5 
 
 1171.2 
 
 46 
 
 275.83 
 
 245.1 
 
 926.6 
 
 1171.7 
 
 47 
 
 277.16 246.4 
 
 925.6 1172.0 
 
 48 
 
 278.47 
 
 247.8 
 
 924.7 
 
 1172.5 
 
 49 
 
 279.76 
 
 249.1 
 
 923.8 
 
 1172.9 
 
 50 
 
 281.03 
 
 250.4 
 
 922.8 
 
 1173.2 
 
 51 
 
 282.28 
 
 251.7 
 
 921.9 
 
 1173.6 
 
 52 
 
 283.52 
 
 253.0 
 
 921.0 
 
 1174.0 
 
 53 
 
 284.74 
 
 254.2 
 
 920.1 
 
 1174.3 
 
 54 
 
 285.93 
 
 255.4 
 
 919.3 
 
 1174.7 
 
 55 
 
 287.09 
 
 256.6 
 
 918.4 
 
 1175.0 
 
 66 
 
 288.25 
 
 257.8 
 
 917.6 
 
 1175.4 
 
 57 
 
 289.40 
 
 259.0 
 
 916.7 
 
 1175.7 
 
 58 
 
 290.53 
 
 260.1 
 
 915.9 
 
 1176.0 
 
 59 
 
 291.64 
 
 261.3 
 
 915.1 
 
 1176.4 
 
 60 
 
 292.74 
 
 262.4 
 
 914.3 
 
 1176.7 
 
 61 
 
 293.82 
 
 263.5 
 
 913.5 
 
 1177.0 
 
 62 
 
 294.88 
 
 264.6 
 
 912.7 
 
 1177.3 
 
 63 
 
 295.93 
 
 265.7 
 
 911.9 
 
 1177.6 
 
 64 
 
 296.97 
 
 266.7 
 
 911.1 
 
 1177.8 
 
 65 
 
 298.00 
 
 267.8 
 
 910.4 
 
 1178.3 
 
 66 
 
 299.02 
 
 268.8 
 
 909.6 
 
 1178.4 
 
 67 
 
 300.02 
 
 269.8 
 
 908.9 
 
 1178.7 
 
 68 
 
 301.01 
 
 270.9 
 
 908.1 
 
 1179.0 
 
 69 
 
 301.99 
 
 271.9 
 
 907.4 
 
 1179.3 
 
 70 
 
 302.96 
 
 272.9 
 
 906.6 
 
 1179.5 
 
 71 
 
 S03.91 
 
 273.8 
 
 905.9 
 
 1179.7 
 
 72 
 
 304.86 
 
 274.8 
 
 905.3 
 
 1180.0 
 
 73 
 
 305.79 
 
 275.8 
 
 904.5 
 
 1180.3 
 
 74 
 
 306.72 
 
 270.7 
 
 903.8 
 
 1180.5 
 
 75 
 
 307.64 
 
 277.7 
 
 903.1 
 
 1180.8 
 
 76 
 
 308.54 
 
 278.6 
 
 902.4 
 
 1181.0 
 
 77 
 
 309.44 
 
 279.5 
 
 901.8 
 
 1181.3 
 
 78 
 
 310.33 
 
 280.4 
 
 901.1 
 
 1181.5 
 
 79 
 
 311.21 
 
 281.3 
 
 900.4 
 
 1181.7 
 
 80 
 
 312.08 
 
 282.2 
 
 899.8 
 
 1182.0 
 
 81 
 
 312.94 
 
 283.1 
 
 899.1 
 
 1182.2 
 
 82 
 
 313.79 
 
 283.9 
 
 898.5 
 
 1182.4 
 
 83 
 
 314.63 
 
 284.8 
 
 897.8 
 
 1182.6 
 
 84 
 
 315.47 
 
 285.7 
 
 897.2 
 
 1182.9 
 
 85 
 
 316.30 
 
 286.5 
 
 896.6 
 
 1183.1 
 
 86 
 
 317.12 
 
 287.4 
 
 895.9 
 
 1183.3 
 
 87 
 
 317.93 
 
 288.2 
 
 895.3 
 
 1183.5 
 
 88 
 
 318.73 
 
 289.0 
 
 894.7 
 
 1183.7 
 
 89 
 
 319.53 
 
 289.9 
 
 894.1 
 
 1184.0 
 
 90 
 
 320.32 
 
 290.7 
 
 893.5 
 
 1184.2 
 
 91 
 
 321.10 
 
 291.5 
 
 892.9 
 
 1184.4 
 
 92 
 
 321.88 
 
 292.3 
 
 892.3 
 
 1184.6 
 
 93 
 
 322.65 
 
 293.1 
 
 891.7 
 
 1184.8 
 
 94 
 
 323.41 
 
 293.9 
 
 891.1 
 
 1185.0 
 
 279 
 
Absolute 
 press 're Ibs. 
 per sq. in. 
 
 Tempera- 
 ture 
 Degrees P. 
 
 Heat 
 of the 
 Liquid 
 
 Heat of the 
 Vaporiza- 
 tion 
 
 Total 
 Heat 
 Above 32 
 
 95 
 
 324.16 
 
 294.6 
 
 890.5 
 
 1185.1 
 
 96 
 
 324.91 
 
 295.4 
 
 889.9 
 
 1185.3 
 
 97 
 
 325.66 
 
 296.2 
 
 889.3 
 
 1185.5 
 
 98 
 
 326.40 
 
 296.9 
 
 888.7 
 
 1185.6 
 
 99 
 
 327.13 
 
 297.7 
 
 888.2 
 
 1185.9 
 
 100 
 
 327.86 
 
 298.5 
 
 887.6 
 
 1186.1 
 
 101 
 
 328.58 
 
 299.2 
 
 887.0 
 
 1186.2 
 
 102 
 
 329.30 
 
 299.9 886.5 
 
 1186.4 
 
 103 
 
 330.01 
 
 300.6 885.9 
 
 1186.5 
 
 104 
 
 330.72 
 
 301.4 
 
 885.3 
 
 1186.7 
 
 105 
 
 331.42 
 
 302.1 
 
 884.8 
 
 1186.9 
 
 106 
 
 332.11 
 
 302.8 
 
 884.3 
 
 1187.1 
 
 107 
 
 332.79 
 
 303.5 
 
 883.7 
 
 1187.2 
 
 108 
 
 333.48 
 
 304.2 
 
 883.2 
 
 1187.4 
 
 109 
 
 334.16 
 
 304.9 
 
 882.6 
 
 1187.5 
 
 110 
 
 334.83 
 
 305.6 
 
 882.1 
 
 1187.7 
 
 111 
 
 335.50 
 
 306.3 
 
 881.6 
 
 1187.9 
 
 112 
 
 336.17 
 
 307.0 
 
 881.0 
 
 1188.0 
 
 113 
 
 336.83 
 
 307.7 
 
 880.5 
 
 1188.2 
 
 114 
 
 337.48 
 
 308.3 
 
 880.0 
 
 1188.3 
 
 115 
 
 338.14 
 
 309.0 
 
 879.5 
 
 1188.5 
 
 116 
 
 338.78 
 
 309.7 
 
 879.0 
 
 1188.7 
 
 117 
 
 339.42 
 
 310.3 
 
 878.5 
 
 1188.8 
 
 118 
 
 340.06 
 
 311.0 878.0 
 
 1189.0 
 
 119 
 
 340.69 
 
 311.7 
 
 877.4 
 
 1189.1 
 
 120 
 
 341.31 
 
 312.3 
 
 876.9 
 
 1189.2 
 
 121 
 
 341.94 
 
 312.9 
 
 876.4 
 
 1189.3 
 
 123 
 
 342.56 
 
 313.6 
 
 875.9 
 
 1189.5 
 
 123 
 
 343.18 
 
 314.2 
 
 875.4 
 
 1189.6 
 
 124 
 
 343.79 
 
 314.8 
 
 875.0 
 
 1189.8 
 
 125 
 
 344.39 
 
 315.5 
 
 874.5 
 
 1190.0 
 
 126 
 
 345.00 
 
 316.1 
 
 874.0 
 
 1190.1 
 
 127 
 
 345.60 
 
 316.7 
 
 873.5 
 
 1190.2 
 
 128 
 
 346.20 
 
 317.3 
 
 873.0 
 
 1190.3 
 
 129 
 
 346.79 
 
 317.9 
 
 872.6 
 
 1190.5 
 
 130 
 
 347.38 
 
 318.6 
 
 872.1 
 
 1190.7 
 
 131 
 
 347.96 
 
 319.2 
 
 871.6 
 
 1190.8 
 
 132 
 
 348.55 
 
 319.8 
 
 871.1 
 
 1190.9 
 
 133 
 
 349.13 
 
 320.4 
 
 870.7 
 
 1191.1 
 
 134 
 
 349.70 
 
 320.9 
 
 870.2 
 
 1191.1 
 
 135 
 
 350.27 
 
 321.5 
 
 869.8 
 
 1191.3 
 
 136 
 
 350.84 
 
 322.1 
 
 869.3 
 
 1191.4 
 
 137 
 
 351.41 
 
 322.7 
 
 868.8 
 
 1191.6 
 
 138 
 
 351.98 
 
 323.3 
 
 868.3 
 
 1191.6 
 
 139 
 
 352.54 
 
 323.9 
 
 867.9 
 
 1191.8 
 
 140 
 
 353.09 
 
 324.4 
 
 867.4 
 
 1191.8 
 
 141 
 
 353.65 
 
 325.0 
 
 867.0 
 
 1192.0 
 
 142 
 
 354.20 
 
 325.6 
 
 866.5 
 
 1192.1 
 
 143 
 
 354.75 
 
 326.2 
 
 866.1 
 
 1192.3 
 
 144 
 
 355.29 
 
 326.7 
 
 865.6 
 
 1192.3 
 
 280 
 
Absolute 
 press 're Ibs. 
 per sq. in. 
 
 Tempera- 
 ture 
 Degrees F. 
 
 Heat 
 of the 
 Liquid 
 
 Heat of the 
 Vaporiza- 
 tion 
 
 Total 
 Heat 
 Above 32 
 
 
 
 1 
 
 
 145 
 
 355.83 
 
 327.3 
 
 865.2 
 
 1193.5 
 
 140 
 
 356.37 
 
 337.8 
 
 864.8 
 
 1192.6 
 
 147 
 
 356.91 
 
 328.4 
 
 864.3 
 
 1192.7 
 
 148 
 
 357.44 
 
 328.9 
 
 863.9 
 
 1192.8 
 
 149 
 
 357.97 
 
 329.5 
 
 863.5 
 
 1193.0 
 
 150 
 
 358.50 
 
 330.0 
 
 863.0 
 
 1193.0 
 
 151 
 
 359.03 
 
 330.6 
 
 863.6 
 
 1193.2 
 
 153 
 
 359.54 
 
 331.1 
 
 862.2 
 
 1193.3 
 
 153 
 
 360.06 
 
 331.6 
 
 861.8 
 
 1193.4 
 
 154 
 
 360.57 
 
 332.2 
 
 861.3 
 
 1193.5 
 
 155 
 
 361.09 
 
 332.7 
 
 860.9 
 
 1193.6 
 
 156 
 
 361.60 
 
 333.2 
 
 860.5 
 
 1193.7 
 
 157 
 
 363.11 
 
 333.8 
 
 860.1 
 
 1193.9 
 
 158 
 
 363.62 
 
 334.3 
 
 859.6 
 
 1193.9 
 
 159 
 
 363.13 
 
 334.8 
 
 859.3 
 
 1194.0 
 
 160 
 
 363.63 
 
 335.3 
 
 858.8 
 
 1194.1 
 
 161 
 
 364.12 
 
 335.9 
 
 858.4 
 
 1194.3 
 
 162 
 
 364.62 
 
 336.4 
 
 858.0 
 
 1194.4 
 
 163 
 
 365.11 
 
 336.9 
 
 857.6 
 
 1194.5 
 
 164 
 
 365.60 
 
 337.4 
 
 857.2 
 
 1194.6 
 
 165 
 
 366.09 
 
 337.9 
 
 856.8 
 
 1194.7 
 
 166 
 
 366.58 
 
 338.4 
 
 856.4 
 
 1194.8 
 
 167 
 
 367.06 
 
 338.9 
 
 856.0 
 
 1194.9 
 
 168 
 
 367.54 
 
 339.4 
 
 855.6 
 
 1195.0 
 
 169 
 
 368.03 
 
 339.9 
 
 855.3 
 
 1195.1 
 
 170 
 
 368.50 
 
 340.4 
 
 854.8 
 
 1196.2 
 
 171 
 
 368.97 
 
 340.9 
 
 854.4 
 
 1195.3 
 
 173 
 
 369.45 
 
 341.4 
 
 854.0 
 
 1195.4 
 
 173 
 
 369.93 
 
 341.8 
 
 853.6 
 
 1195.4 
 
 174 
 
 370.39 
 
 342.3 
 
 853.3 
 
 1195.5 
 
 175 
 
 370.86 
 
 342.8 
 
 852.8 
 
 1195.6 
 
 176 
 
 371.33 
 
 343.3 
 
 852.4 
 
 1195.7 
 
 177 
 
 371.78 
 
 343.8 
 
 853.0 
 
 1195.8 
 
 178 
 
 373.24 
 
 344.2 
 
 851.6 
 
 1195.8 
 
 179 
 
 373.70 
 
 344.7 
 
 851.3 
 
 1196.0 
 
 180 
 
 373.16 
 
 345.2 
 
 850.9 
 
 1196.1 
 
 181 
 
 373.61 
 
 345.7 
 
 850.5 
 
 1196.2 
 
 183 
 
 374.07 
 
 346.2 
 
 850.1 
 
 1196.3 
 
 183 
 
 374.53 
 
 346.6 
 
 849.7 
 
 1196.3 
 
 184 
 
 374.98 
 
 347.1 
 
 849.4 
 
 1196.5 
 
 185 
 
 375.41 
 
 347.5 
 
 849.0 
 
 1196.5 
 
 186 
 
 375.86 
 
 348.0 
 
 848.6 
 
 1196.6 
 
 187 
 
 376.30 
 
 348.5 
 
 848.3 
 
 1196.7 
 
 188 
 
 376.74 
 
 348.9 
 
 847.8 
 
 1198.7 
 
 189 
 
 377.18 
 
 349.4 
 
 847.5 
 
 1196.9 
 
 190 
 
 377.61 
 
 349.8 
 
 847.1 
 
 1196.9 
 
 191 
 
 378.05 
 
 350.3 
 
 846.8 
 
 1197.1 
 
 192 
 
 378.49 
 
 350.7 
 
 846.4 
 
 1197.1 
 
 193 
 
 378.92 
 
 351.3 
 
 846.0 
 
 1197.2 
 
 194 
 
 379.35 
 
 351.6 
 
 845.7 
 
 1197.3 
 
 281 
 
Absolute 
 press're Ibs. 
 per sq. in. 
 
 Tempera- 
 ture 
 Degrees F. 
 
 Heat 
 of the 
 Liquid 
 
 Heat of the 
 Vaporiza- 
 tion 
 
 Total 
 Heat 
 Above 32 
 
 195 
 
 379.78 
 
 352.1 
 
 845.3 
 
 1197.4 
 
 196 
 
 380.20 
 
 352.5 
 
 844.9 
 
 1197.4 
 
 197 
 
 380.63 
 
 353.0 
 
 844.6 
 
 1197.6 
 
 198 381.05 
 
 353.4 
 
 844.2 
 
 1197.6 
 
 19 
 
 381.47 
 
 353.8 
 
 843.9 
 
 1197.7 
 
 200 
 
 381.89 
 
 354.3 
 
 843.5 
 
 1197.8 
 
 201 
 
 382.31 
 
 354. '< 
 
 843.1 
 
 1197.8 
 
 202 
 
 S82.73 
 
 355.1 
 
 842.8 
 
 1197.9 
 
 203 
 
 383.15 
 
 355.6 
 
 842.4 
 
 1198.0 
 
 204 
 
 383.56 
 
 356.0 
 
 842.1 
 
 1198.1 
 
 5-05 
 
 383.98 
 
 356.4 
 
 841.7 
 
 1198.1 
 
 06 
 
 384.39 
 
 356.9 
 
 841.3 
 
 1198.2 
 
 2O7 
 
 384.80 
 
 357.3 
 
 841.0 
 
 1198.3 
 
 208 
 
 385.21 
 
 357.7 
 
 840.7 
 
 1198.4 
 
 209 
 
 385.61 
 
 358.1 
 
 840.3 
 
 1198.4 
 
 310 
 
 386.02 
 
 358.6 
 
 840.0 
 
 1198.6 
 
 211 
 
 386.42 
 
 359.0 
 
 839.6 
 
 1198.6 
 
 212 
 
 386.82 
 
 359.4 
 
 839.3 
 
 1198.7 
 
 213 
 
 387.22 
 
 359.8 
 
 839.0 
 
 1198.8 
 
 214 
 
 387.62 
 
 360.2 
 
 838.6 
 
 1198.8 
 
 215 
 
 388.02 
 
 360.6 
 
 838.3 
 
 1198.9 
 
 216 
 
 388.41 
 
 361.0 
 
 837.9 
 
 1198.9 
 
 217 
 
 388.80 
 
 361.4 
 
 837.6 
 
 1199.0 
 
 218 
 
 389.20 
 
 361.9 
 
 837.2 
 
 1199.1 
 
 219 
 
 389.59 
 
 362.3 
 
 836.9 
 
 1199.2 
 
 230 
 
 389.98 
 
 362.7 
 
 836.6 
 
 1199.3 
 
 221 
 
 390.37 
 
 363.1 
 
 836.2 
 
 1199.3 
 
 222 
 
 390.76 
 
 363.5 
 
 835.9 
 
 1199.4 
 
 223 
 
 391.14 
 
 363.9 
 
 835.6 
 
 1199.5 
 
 224 
 
 391.53 
 
 364.3 
 
 835.2 
 
 1199.5 
 
 225 
 
 391.91 
 
 364.7 
 
 834.9 
 
 1199.8 
 
 226 
 
 392.29 
 
 365.1 
 
 834.6 
 
 1199.7 
 
 227 
 
 392.67 
 
 365.5 
 
 834.3 
 
 1199.8 
 
 228 
 
 393.04 
 
 365.9 
 
 833.9 
 
 1199.8 
 
 229 
 
 393.42 
 
 366.2 
 
 833.6 
 
 1199.8 
 
 230 
 
 393.80 
 
 366.6 
 
 833.3 
 
 1199.9 
 
 231 
 
 394.18 
 
 367.0 
 
 832.9 
 
 1199.9 
 
 232 
 
 394.56 
 
 367.4 
 
 832.6 
 
 1200.0 
 
 233 
 
 394.93 
 
 367.8 
 
 832.3 
 
 1200.1 
 
 234 
 
 395.30 
 
 368.2 
 
 832.0 
 
 1200.2 
 
 235 
 
 395.67 
 
 368.6 
 
 831.7 
 
 1200.3 
 
 236 
 
 396.04 
 
 369.0 
 
 831.3 
 
 1200.3 
 
 237 
 
 396.41 
 
 369.4 
 
 831.0 
 
 1200.4 
 
 238 
 
 c96.78 
 
 369.7 
 
 830.7 
 
 1200.4 
 
 239 
 
 397.14 
 
 370.1 
 
 830.4 
 
 1200.5 
 
 240 
 
 397.50 
 
 370.5 
 
 830.1 
 
 1200.6 
 
 241 
 
 397.86 
 
 370.9 
 
 829.8 
 
 1200.7 
 
 242 
 
 398.22 
 
 371.2 
 
 829.5 
 
 1200.7 
 
 243 
 
 398.59 
 
 371.6 
 
 829.1 
 
 1200.7 
 
 244 
 
 398.96 
 
 372.0 
 
 828.8 
 
 1200.8 
 
 282 
 
Absolute 
 press're Ibs. 
 per sq. in. 
 
 Tempera- 
 ture 
 Degrees F. 
 
 Heat 
 of the 
 Liquid 
 
 Heat of the 
 Vaporiza- 
 tion 
 
 Total 
 Heat 
 Above 32 
 
 245 
 
 399.32 
 
 372.4 
 
 828.5 
 
 1200.9 
 
 246 
 
 399.68 
 
 372.8 
 
 828.2 
 
 1201.0 
 
 247 
 
 400.04 
 
 373.2 
 
 827.8 
 
 1201.0 
 
 248 
 
 400.39 
 
 373.5 
 
 827.5 
 
 1201.0 
 
 249 
 
 400.75 
 
 373.9 
 
 827.2 
 
 1201.1 
 
 250 
 
 401.10 
 
 374.2 
 
 826.9 
 
 1201.1 
 
 251 
 
 401.45 
 
 374.6 
 
 826.6 
 
 1201.2 
 
 262 
 
 401.79 
 
 375.0 
 
 826.3 
 
 1201.3 
 
 253 
 
 402.14 
 
 375.3 
 
 826.0 
 
 1201.3 
 
 254 
 
 402.48 
 
 375.7 
 
 825.7 
 
 1201.4 
 
 255 
 
 402.83 
 
 376.0 
 
 825.4 
 
 1201.4 
 
 256 
 
 403.17 
 
 376.4 
 
 825.1 
 
 1201.6 
 
 257 
 
 403.52 
 
 376.8 
 
 824.8 
 
 1201.6 
 
 258 
 
 403.86 
 
 377.1 
 
 824.5 
 
 1201.6 
 
 259 
 
 404.21 
 
 377.5 
 
 824.2 
 
 1201.7 
 
 260 
 
 404.55 
 
 377.8 
 
 823.9 
 
 1201.7 
 
 261 
 
 404.89 
 
 378.2 
 
 823.6 
 
 1201.8 
 
 262 
 
 405.23 
 
 378.5 
 
 823.3 
 
 1201.8 
 
 263 
 
 405.57 
 
 378.9 
 
 823.0 
 
 1201.9 
 
 264 
 
 405.90 
 
 379.2 
 
 822.7 
 
 1201.9 
 
 265 
 
 406.23 
 
 379.6 
 
 822.4 
 
 1202.0 
 
 268 
 
 406.57 
 
 379.9 
 
 822.1 
 
 1202.0 
 
 267 
 
 406.90 
 
 380.3 
 
 821.8 
 
 1202.1 
 
 268 
 
 407.23 
 
 380.6 
 
 821.5 
 
 1202.1 
 
 . 269 
 
 407.57 
 
 381.0 
 
 821.2 
 
 1202.2 
 
 270 
 
 407.90 
 
 381.3 
 
 820.9 
 
 1202.2 
 
 271 
 
 408.23 
 
 381.7 
 
 820.6 
 
 1202.3 
 
 272 
 
 408.57 
 
 382.0 
 
 820.3 
 
 1202.3 
 
 273 
 
 408.90 
 
 382.4 
 
 820.1 
 
 1202.5 
 
 274 
 
 409.23 
 
 382.7 
 
 819.8 
 
 1202.5 
 
 275 
 
 409.57 
 
 383.1 
 
 819.5 
 
 1202.6 
 
 276 
 
 409.90 
 
 383.4 
 
 819.2 
 
 1202.6 
 
 277 
 
 410.23 
 
 383.8 
 
 818.9 
 
 1202.7 
 
 278 
 
 410.55 
 
 384.1 
 
 818.6 
 
 1202.7 
 
 279 
 
 410.87 
 
 384.4 
 
 818.3 
 
 1202.7 
 
 280 
 
 411.19 
 
 384.8 
 
 818.0 
 
 1202.8 
 
 281 
 
 411.52 
 
 385.1 
 
 817.7 
 
 1202.8 
 
 
 411.84 
 
 385.4 
 
 817.4 
 
 1202.8 
 
 283 
 
 412.16 
 
 385.8 
 
 817.2 
 
 1203.0 
 
 284 
 
 412.47 
 
 386.1 
 
 816.9 
 
 1203.0 
 
 285 
 
 412.78 
 
 386.4 
 
 816.6 
 
 1203.0 
 
 286 
 
 413.09 
 
 386.7 
 
 816.3 
 
 1203.0 
 
 287 
 
 413.41 
 
 387.1 
 
 8i6.0 
 
 1203.1 
 
 288 
 
 413.72 
 
 387.4 
 
 815.8 
 
 1203.2 
 
 289 
 
 414.03 
 
 387.7 
 
 815.5 
 
 1203.2 
 
 290 
 
 414.35 
 
 388.1 
 
 815.2 
 
 1203.3 
 
 291 
 
 414.68 
 
 388.4 
 
 814.9 
 
 1203.3 
 
 293 
 
 415.00 
 
 388.7 
 
 814.0 
 
 1203.3 
 
 293 
 
 415.31 
 
 389.1 
 
 814.3 
 
 1203.4- 
 
 294 
 
 415.63 
 
 389.4 
 
 814.1 
 
 1203.5 
 
 283 
 
Absolute 
 Pressure 
 Pounds Per 
 Square Inch 
 
 Temperature 
 Degrees 
 Fahrenheit 
 
 Heat of the 
 Liquid 
 
 Heat of the 
 Vaporization 
 
 Total Heat 
 Above 32 
 
 295 
 
 415.95 
 
 389.7 
 
 813.8 
 
 1203.5 
 
 293 
 
 416.24 
 
 390.0 
 
 813.5 
 
 1203.5 
 
 297 
 
 416.55 
 
 390.4 
 
 813.2 
 
 1203.6 
 
 298 
 
 416.85 
 
 390.7 
 
 813.0 
 
 1203.7 
 
 299 
 
 417.15 
 
 391.0 
 
 812.7 
 
 1203.7 
 
 300 
 
 417.45 
 
 391.3 
 
 812.4 
 
 1203.7 
 
 301 
 
 417.76 
 
 391.6 
 
 812.1 
 
 1203.7 
 
 303 
 
 418.06 
 
 391.9 
 
 811.9 
 
 1203.8 
 
 303 
 
 418.36 
 
 392.3 
 
 811.6 
 
 1203.9 
 
 804 
 
 418.67 
 
 392.6 
 
 811.3 
 
 1203.9 
 
 SOS 
 
 418.97 
 
 392.9 
 
 811.1 
 
 1204.0 
 
 306 
 
 419.26 
 
 393.2 
 
 810.8 
 
 1204.0 
 
 807 
 
 419.56 
 
 393.5 
 
 810.5 
 
 1204.0 
 
 808 
 
 419.85 
 
 393.8 
 
 810.3 
 
 1204.1 
 
 309 
 
 420.15 
 
 394.1 
 
 810.0 
 
 1204.1 
 
 310 
 
 420.45 
 
 394.4 
 
 809.7 
 
 1204.1 
 
 311 
 
 420.76 
 
 394.8 
 
 809.5 
 
 1204.3 
 
 812 
 
 421.06 
 
 395.1 
 
 809.2 
 
 1204.3 
 
 313 
 
 421.35 
 
 395.4 
 
 808.9 
 
 1204.3 
 
 314 
 
 421.65 
 
 395.7 
 
 808.7 
 
 JEZ04.4 
 
 315 
 
 421.94 
 
 396.0 
 
 808.4 
 
 1204.4 
 
 316 
 
 422.24 
 
 396.3 
 
 808.1 
 
 1204.4 
 
 317 
 
 422.53 
 
 396.6 
 
 807.9 
 
 1204.5 
 
 318 
 
 422.82 
 
 396.9 
 
 807.6 
 
 1204.5 
 
 319 
 
 423.11 
 
 397.2 
 
 807.3 
 
 1204.5 
 
 320 
 
 423.40 
 
 397.5 
 
 807.1 
 
 1204.6 
 
 321 
 
 423.69 
 
 397.8 
 
 806.8 
 
 1204.6 
 
 322 
 
 423.97 
 
 398.1 
 
 806.6 
 
 1204.7 
 
 823 
 
 424.26 
 
 398.4 
 
 806.3 
 
 1204.7 
 
 824 
 
 424.54 
 
 398.7 
 
 806.0 
 
 1204.7 
 
 325 
 
 424.83 
 
 399.0 
 
 805.8 
 
 1204.8 
 
 326 
 
 425.11 
 
 399.3 
 
 805.5 
 
 1204.8 
 
 327 
 
 425.40 
 
 399.6 
 
 805.3 
 
 1204.9 
 
 328 
 
 425.69 
 
 399.9 
 
 805.0 
 
 1204.9 
 
 329 
 
 425.97 
 
 400.2 
 
 804.7 
 
 1204.9 
 
 330 
 
 426.26 
 
 400.5 
 
 804.5 
 
 1205.0 
 
 311 
 
 426.54 
 
 400.8 
 
 804.2 
 
 1205.0 
 
 ' 332 
 
 426.83 
 
 401.1 
 
 804.0 
 
 1205.1 
 
 333 
 
 427.11 
 
 401.4 
 
 808.7 
 
 1205.1 
 
 334 
 
 427.39 
 
 401.7 
 
 803.5 
 
 1205.2 
 
 335 
 
 427.67 
 
 402.0 
 
 803.2 
 
 1205.2 
 
 836 
 
 427.94 
 
 402.2 
 
 803.0 
 
 1205.2 
 
 284 
 
TABLE 3. 
 Naperian Logarithms. 
 
 2.7182818 Log e = 0.4342945 
 
 = M. 
 
 .0 
 
 0.0000 
 
 4.1 
 
 .4110 
 
 7.2 
 
 1.9741 
 
 .1 
 
 0.0953 
 
 4.2 
 
 .4351 
 
 7.3 
 
 1.9879 
 
 .2 
 
 0.1823 
 
 4.3 
 
 .4586 
 
 7.4 
 
 2.0015 
 
 .3 
 
 0.2624 
 
 .4 
 
 .4816 
 
 7.5 
 
 2.0149 
 
 .4 
 
 0.3365 
 
 .6 
 
 .5041 
 
 7.6 
 
 2.0281 
 
 .5 
 
 0.4055 
 
 .6 
 
 1.5261 
 
 7.7 
 
 2.0412 
 
 .6 
 
 0.4700 
 
 .7 
 
 1.5476 
 
 7.8 
 
 2.0541 
 
 .7 
 
 0.5306 
 
 .8 
 
 1.5686 
 
 7.9 
 
 2.0668 
 
 .8 
 
 0.5878 
 
 4.9 
 
 1.5892 
 
 8.0 
 
 2.0794 
 
 .9 
 
 0.6418 
 
 6.0 
 
 1.6094 
 
 8.1 
 
 2.0919 
 
 2.0 
 
 0.6931 
 
 6.1 
 
 1.6292 
 
 8.3 
 
 2.1041 
 
 2.1 
 
 0.7419 
 
 5.2 
 
 1.6487 
 
 8.3 
 
 2.1163 
 
 2.2 
 
 0.7884 
 
 5.3 
 
 1.6677 
 
 8.4 
 
 2.1283 
 
 2.3 
 
 0.8329 
 
 5.4 
 
 1.6864 
 
 8.5 
 
 2.1401 
 
 2.4 
 
 0.8755 
 
 5.5 
 
 .7047 
 
 8.6 
 
 2.1518 
 
 2.5 
 
 0.9163 
 
 6.6 
 
 .7228 
 
 8.7 
 
 2.1633 
 
 2.6 
 
 0.9555 
 
 5.7 
 
 .7405 
 
 8.8 
 
 2.1748 
 
 2.7 
 
 0.9933 
 
 5.8 
 
 .7579 
 
 8.9 
 
 2.1861 
 
 2.8 
 
 .0296 
 
 5.9 
 
 .7750 
 
 9.0 
 
 2.1972 
 
 2.9 
 
 .0647 
 
 6.0 
 
 .7918 
 
 9.1 
 
 2.2083 
 
 3.0 
 
 .0986 
 
 6.1 
 
 .8083 
 
 9.2 
 
 2.2192 
 
 3.1 
 
 .1314 
 
 6.2 
 
 .8245 
 
 9.3 
 
 2.2300 
 
 3.3 
 
 .1632 
 
 6.3 
 
 .8405 
 
 9.4 
 
 2.2407 
 
 3.3 
 
 .1939 
 
 6.4 
 
 .8563 
 
 9.5 
 
 2.2513 
 
 3.4 
 
 .2238 
 
 6.5 
 
 .8718 
 
 9.6 
 
 2.2618 
 
 3.5 
 
 .2528 
 
 6.6 
 
 .8871 
 
 9.7 
 
 2.2721 
 
 3.6 
 
 .2809 
 
 6.7 
 
 .9021 
 
 9.8 
 
 2.2824 
 
 3.7 
 
 .3083 
 
 6.8 
 
 1.9169 
 
 9.9 
 
 2.2925 
 
 3.8 
 
 .3350 
 
 6.9 
 
 1.9315 
 
 10.0 
 
 2.3026 
 
 3.9 
 
 1.3610 
 
 7.0 
 
 1.9459 
 
 
 
 4.0 
 
 1.3863 
 
 7.1 
 
 1.9601 
 
 
 
 TABLE 4. 
 Water Conversion Factors.* 
 
 TJ. S. gallons 
 U. S. gallons 
 U. S. gallons 
 U. S. gallons 
 Cubic inches of water (39.1) 
 Cubic inches of water (39.1) 
 Cubic inches of water (39.1) 
 Cubic feet of water (89.1) 
 Cubic feet of water (39.1) 
 Cubic feet of water (39.1) 
 Pounds of water 
 Pounds of water 
 Pounds of water 
 
 X 
 
 X 
 X 
 X 
 X 
 X 
 X 
 X 
 X 
 X 
 X 
 X 
 X 
 
 8.33 
 0.13368 
 231.00000 
 3.78 
 0.036024 
 0.004329 
 0.576384 
 62.425 
 7.48 
 0.028 
 27.72 
 0.01602 
 0.12 
 
 
 
 pounds, 
 cubic feet, 
 cubic inches, 
 liters, 
 pounds. 
 U. S. gallons, 
 ounces, 
 pounds. 
 U. S. gallons, 
 tons, 
 cubic inches, 
 cubic feet. 
 U. S. gallons. 
 
 * American Machinist Hand Book. 
 285 
 
TABLE 5. 
 Volume and Weight of Wry Air at Different Temperatures.* 
 
 Under a constant atmospheric pressure of 29.92 inches of 
 mercury, the volume at 32 F. being 1. 
 
 Tempera- 
 ture 
 
 Volume. 
 
 Weight of 
 a Cubic 
 
 Tempera- 
 ture 
 
 Weight of 
 Volume. a Cubic 
 
 Fahr. 
 
 
 Foot. 
 
 Fahr. 
 
 Foot. 
 
 
 
 .935 
 
 .0864 
 
 500 
 
 1.954 
 
 .0413 
 
 12 
 
 .960 
 
 .0842 
 
 552 
 
 2.056 
 
 .0385 
 
 221 
 
 .980 
 
 .0824 
 
 600 
 
 2.150 
 
 .0376 
 
 32 
 
 1.000 
 
 .0807 
 
 650 
 
 2.260 
 
 .0357 
 
 42 
 
 1.020 
 
 .0791 
 
 700 
 
 2.362 
 
 .0338 
 
 52 
 
 1.041 
 
 .0776 
 
 750 
 
 2.465 
 
 .0328 
 
 62 
 
 1.061 
 
 .0761 
 
 800 
 
 2.566 
 
 .0315 
 
 72 
 
 1.082 
 
 .0747 
 
 850 
 
 2.668 
 
 .0303 
 
 82 
 
 1.102 
 
 .0733 
 
 900 
 
 2.770 
 
 .0292 
 
 92 
 
 1.122 
 
 .0720 
 
 950 
 
 2.871 
 
 .0281 
 
 102 
 
 1.143 
 
 .0707 
 
 1000 
 
 2.974 
 
 .0268 
 
 112 
 
 1.163 
 
 .0694 
 
 1100 
 
 3.177 
 
 .0264 
 
 122 
 
 1.184 
 
 .0682 1200 
 
 3.381 
 
 .0239 
 
 132 
 
 1.204 
 
 .0671 1300 
 
 3.584 
 
 .0225 
 
 142 
 
 1.224 
 
 .0659 1400 
 
 3.788 
 
 .0313 
 
 152 
 
 1.245 
 
 .0649 1500 
 
 3.993 
 
 .0202 
 
 162 
 
 1.265 
 
 .0638 
 
 1600 
 
 4.196 
 
 .0192 
 
 172 
 
 1.285 
 
 .0628 
 
 1700 
 
 4.402 
 
 .0183 
 
 182 
 
 1.306 
 
 .0618 
 
 1800 
 
 4.605 
 
 .0175 
 
 192 
 
 1.326 
 
 .0609 
 
 1900 
 
 4.808 
 
 .0168 
 
 202 
 
 1.347 
 
 .0600 
 
 2000 
 
 5.012 
 
 .0161 
 
 212 
 
 1.367 
 
 .0591 
 
 2100 
 
 5.217 
 
 .0155 
 
 230 
 
 1.404 
 
 .0575 
 
 2200 
 
 5.420 
 
 .0149 
 
 250 
 
 1.444 
 
 .0559 
 
 2300 
 
 5.625 
 
 .0142 
 
 275 
 
 1.495 
 
 .0540 
 
 2400 
 
 5.827 
 
 .0138 
 
 300 
 
 1.546 
 
 .0522 
 
 2500 
 
 6.032 
 
 .0133 
 
 325 
 
 1.597 
 
 .0506 
 
 2600 
 
 6.236 
 
 .0130 
 
 350 
 
 1.648 
 
 .0490 2700 
 
 6.440 
 
 .0125 
 
 375 
 
 1.689 
 
 .0477 2800 
 
 6.644 
 
 .0121 
 
 400 
 
 1.750 
 
 .0461 
 
 2900 
 
 6.847 
 
 .0118 
 
 450 
 
 1.852 
 
 .0436 
 
 3000 
 
 7.051 
 
 .0114 
 
 *Suplee's M. E. Eeference Book. 
 
 286 
 
TABLE 6. 
 
 Weight of Pure Water per Cubic Foot at Various 
 Temperature.* 
 
 Temp. 
 Degrees 
 Fahr. 
 
 Weight 
 Lbs. per 
 Cu. Ft. 
 
 B. t. u. 
 Per Pound 
 above 33. 
 
 Temp. 
 Degrees 
 Fahr. 
 
 Weight 
 Lbs. per 
 Cu. Ft. 
 
 B. t. u. 
 Per Pound 
 above 3$. 
 
 32 
 
 62.42 
 
 0.00 
 
 77 
 
 62.26 
 
 45.03 
 
 33 
 
 62.42 
 
 1.00 
 
 78 
 
 63.25 
 
 46.03 
 
 34 
 
 62.42 
 
 2.00 
 
 79 
 
 62.34 
 
 47.03 
 
 35 
 
 62.42 
 
 3.00 
 
 80 
 
 63.23 
 
 48.04 
 
 36 
 
 62.42 
 
 4.00 
 
 81 
 
 62.22 
 
 49.04 
 
 37 
 
 62.42 
 
 5.00 
 
 83 
 
 62.21 
 
 50.04 
 
 38 
 
 62.43 
 
 6.00 
 
 83 
 
 62.20 
 
 51.04 
 
 39 
 
 62.43 
 
 7.00 
 
 84 
 
 62.19 
 
 53.04 
 
 40 
 
 62.42 
 
 8.00 
 
 85 
 
 62.18 
 
 53.05 
 
 41 
 
 62.43 
 
 9.00 
 
 86 
 
 62.17 
 
 54.05 
 
 42 
 
 62.42 
 
 10.00 
 
 87 
 
 62.16 
 
 55.05 
 
 43 
 
 62.42 
 
 11.00 
 
 88 
 
 62.15 
 
 56.05 
 
 44 
 
 62.42 
 
 12.00 
 
 89 
 
 62.14 
 
 57.05 
 
 45 
 
 62.42 
 
 13.00 
 
 90 
 
 62.13 
 
 58.06 
 
 46 
 
 62.43 
 
 14.00 
 
 91 
 
 62.12 
 
 59.06 
 
 47 
 
 62.42 
 
 15.00 
 
 93 
 
 62.11 
 
 60.06 
 
 48 
 
 62.41 
 
 16.00 
 
 93 
 
 62.10 
 
 61.0(5 
 
 49 
 
 62.41 
 
 17.00 
 
 94 
 
 62.09 
 
 62.06 
 
 50 
 
 62.41 
 
 18.00 
 
 95 
 
 62.08 
 
 63.07 
 
 51 
 
 62.41 
 
 19.00 
 
 96 
 
 62.07 
 
 64.07 
 
 52 
 
 62.40 
 
 20.00 
 
 97 
 
 62.06 
 
 65.07 
 
 53 
 
 62.40 
 
 21.01 
 
 98 
 
 62.06 
 
 66.07 
 
 54 
 
 62.40 
 
 22.01 
 
 99 
 
 62.03 
 
 67.08 
 
 55 
 
 62.39 
 
 23.01 
 
 100 
 
 63.02 
 
 68.08 
 
 56 
 
 62.39 
 
 24.01 
 
 101 
 
 62.01 
 
 69.08 
 
 57 
 
 63.39 
 
 25.01 
 
 102 
 
 62.00 
 
 70.09 
 
 58 
 
 62.38 
 
 26.01 
 
 103 
 
 61.99 
 
 71.09 
 
 59 
 
 62.38 
 
 27.01 
 
 104 
 
 61.97 
 
 72.09 
 
 60 
 
 62.37 
 
 28.01 
 
 105 
 
 61.96 
 
 73.10 
 
 01 
 
 62.37 
 
 29.01 
 
 106 
 
 61.95 
 
 74.10 
 
 63 
 
 62.36 
 
 30.01 
 
 107 
 
 61.93 
 
 75.10 
 
 63 
 
 62.36 
 
 31.01 
 
 108 
 
 61.92 
 
 76.10 
 
 64 
 
 62.35 
 
 32.01 
 
 109 
 
 61.91 
 
 77.11 
 
 65 
 
 62.34 
 
 33.01 
 
 110 
 
 61.89 
 
 78.11 
 
 66 
 
 62.34 
 
 34.02 
 
 111 
 
 61.88 
 
 79.11 
 
 67 
 
 62.33 
 
 35.02 
 
 112 
 
 61.86 
 
 80.12 
 
 68 
 
 62.33 
 
 36.02 
 
 113 
 
 61.85 
 
 81.12 
 
 69 
 
 62.32 
 
 37.02 
 
 114 
 
 61.83 
 
 83.13 
 
 70 
 
 62.31 
 
 38.03 
 
 115 
 
 61.83 
 
 83.13 
 
 71 
 
 62.31 
 
 39.02 
 
 116 
 
 61.80 
 
 84.13 
 
 72 
 
 62.30 
 
 40.02 
 
 117 
 
 61.78 
 
 85.14 
 
 73 
 
 62.29 
 
 41.02 
 
 118 
 
 61.77 
 
 86.14 
 
 74 
 
 62.28 
 
 42.03 
 
 119 
 
 61.75 
 
 87.15 
 
 75 
 
 62.28 
 
 43.03 
 
 120 
 
 61.74 
 
 88.15 
 
 76 
 
 62.27 
 
 44.03 
 
 121 
 
 61.72 
 
 89.15 
 
 "Kent's M. E. Pocket-Book. 
 
 287 
 
Temp. 
 Degrees 
 Fahr. 
 
 Weight 
 Lbs. per 
 Cu. Ft. 
 
 B. t. u. Temp. 
 Per Pound Degrees 
 above 32. Fahr. 
 
 Weight 
 Lbs. per 
 Cu. Ft. 
 
 B. t. u. 
 Per Pound 
 above 32. 
 
 122 
 
 61.70 
 
 90.16 
 
 167 
 
 60.83 
 
 135.43 
 
 123 
 
 61.68 
 
 91.16 168 
 
 60.81 
 
 136.44 
 
 124 
 
 61.67 
 
 92.17 169 
 
 60.79 
 
 137.45 
 
 125 
 
 61.65 
 
 93.17 
 
 170 
 
 60.77 
 
 138.45 
 
 120 
 
 61.63 
 
 94.17 
 
 171 
 
 a. 75 
 
 139.46 
 
 127 
 
 61.61 
 
 95.18 
 
 172 
 
 60.73 
 
 140.47 
 
 128 
 
 61.60 
 
 96.18 
 
 173 
 
 60.70 141.48 
 
 129 
 
 61.58 
 
 97.19 
 
 174 
 
 60.68 142.49 
 
 130 
 
 61.56 
 
 98.19 
 
 17 
 
 60.68 " 143.50 
 
 131 
 
 61.54 
 
 99.20 
 
 176 
 
 60.64 144.51 
 
 133 
 
 61.52 
 
 100.20 
 
 177 
 
 60.62 145.52 
 
 133 
 
 61.51 
 
 101.21 
 
 ITS 
 
 60.59 
 
 146.52 
 
 134 
 
 61.49 
 
 102.21 
 
 179 
 
 60.57 
 
 147.53 
 
 135 
 
 61.47 
 
 103.22 
 
 180 
 
 60.55 
 
 148.54 
 
 136 
 
 61.45 
 
 104.22 
 
 181 
 
 60.53 
 
 149.55 
 
 137 
 
 61.43 
 
 105.23 
 
 182 
 
 60.50 
 
 150.56 
 
 138 
 
 61.41 
 
 106.23 
 
 183 
 
 60.48 
 
 151.57 
 
 139 
 
 61.39 
 
 107.24 
 
 184 
 
 (50.46 
 
 152.58 
 
 140 
 
 61.37 
 
 108.25 
 
 185 
 
 60.44 
 
 153.59 
 
 141 
 
 61.36 
 
 109.25 
 
 186 
 
 60.41 
 
 154.60 
 
 142 
 
 61.34 
 
 110.26 
 
 187 
 
 60.39 
 
 155. 6 1 
 
 143 
 
 61.32 
 
 111.26 
 
 188 
 
 60.37 
 
 156.62 
 
 144 
 
 61.30 
 
 112.27 
 
 189 
 
 60.34 
 
 157.63 
 
 145 
 
 61.28 
 
 113.28 
 
 190 
 
 60.32 
 
 158.64 
 
 140 
 
 61.26 
 
 114.28 
 
 191 
 
 60.29 
 
 159.65 
 
 147 
 
 61.24 
 
 115.29 
 
 192 
 
 60.27 
 
 160.67 
 
 148 
 
 61.23 
 
 116.29 
 
 193 
 
 60.25 
 
 161.68 
 
 149 
 
 61.20 
 
 117.30 
 
 194 
 
 60.22 
 
 162.69 
 
 150 
 
 61.18 
 
 118.31 
 
 195 
 
 60.20 
 
 163.70 
 
 151 
 
 61.16 
 
 119.31 
 
 196 
 
 60.17 
 
 164.71 
 
 152 
 
 61.14 
 
 120.32 
 
 197 
 
 60.15 
 
 165.72 
 
 153 
 
 61.12 
 
 121.33 
 
 198 
 
 60.12 
 
 166.73 
 
 154 
 
 61.10 
 
 122.33 
 
 199 
 
 60.10 
 
 167.74 
 
 155 
 
 61.08 
 
 123.34 
 
 200 
 
 60.07 
 
 168.75 
 
 156 
 
 61.06 
 
 124.35 
 
 201 
 
 60.05 
 
 169.77 
 
 157 
 
 61.04 
 
 125.35 
 
 202 
 
 60.02 
 
 170.78 
 
 158 
 
 61.02 
 
 126.36 
 
 203 
 
 60.00 
 
 171.79 
 
 159 
 
 61.00 
 
 127.37 
 
 204 
 
 59.97 
 
 172.80 
 
 -160 
 
 60.98 
 
 128.37 
 
 205 
 
 59.95 
 
 173.81 
 
 161 
 
 60.96 
 
 129.38 
 
 206 
 
 59.92 
 
 174.83 
 
 162 
 
 60.94 
 
 130.39 
 
 207 
 
 59.89 
 
 175.84 
 
 163 
 
 60.92 
 
 131.40 
 
 206 
 
 59.87 
 
 176.85 
 
 164 
 
 60.90 
 
 132.41 
 
 209 
 
 59.84 
 
 177.86 
 
 165 
 
 60.87 
 
 133.41 
 
 210 
 
 59.82 
 
 178.87 
 
 166 
 
 60.85 
 
 134.42 
 
 211 
 
 59.79 
 
 179.89 
 
 
 
 
 212 
 
 59.76 
 
 180.90 
 
 288 
 
TABLE 7. 
 Boiling: Points of Water at Different Heights of Vacuui 
 
 Temperature 
 Fahr. 
 
 Height of 
 Mercury in 
 Vacuum Tube 
 in Inches. 
 
 Temperature 
 Fahr. 
 
 Height of 
 Mercury in 
 Vacuum Tube 
 in Inches. 
 
 212.0 
 
 0.00 
 
 175.8 
 
 16.00 
 
 210.3 
 
 1.00 
 
 172.6 
 
 17.00 
 
 208.5 
 
 2.00 
 
 169.0 
 
 18.00 
 
 206.8 
 
 3.00 
 
 165.3 
 
 19.00 
 
 204.8 
 
 4.00 
 
 161.2 
 
 20.00 
 
 202.9 
 
 5.00 
 
 156.7 
 
 21.00 
 
 200.9 
 
 6.00 
 
 151.9 
 
 22.00 
 
 199.0 
 
 7.00 
 
 146.5 
 
 23.00 
 
 196.7 
 
 8.00 
 
 140.3 
 
 24.00 
 
 194.5 
 
 9.00 
 
 133.3 
 
 25.00 
 
 192. 2 
 
 10.00 
 
 124.9 
 
 26.00 
 
 189.7 
 
 11.00 
 
 114.4 
 
 27.00 
 
 187.3 
 
 12.00 
 
 108.4 
 
 28.00 
 
 184.6 
 
 13.00 
 
 102.0 
 
 29.00 
 
 181.3 
 
 14.00 
 
 98.0 
 
 29.92 
 
 178.9 
 
 15.00 
 
 
 
 TABLE 8. 
 
 Weight of Water With Air Per Cubic Foot at Different 
 Temperatures and Saturation. 
 
 fc 
 
 
 fe 
 
 
 . 
 
 
 . 
 
 
 . 
 
 
 & 
 
 
 _ 
 
 -M m 
 
 
 
 4J ' 
 
 m 
 
 ** 
 
 
 
 -P" .J 
 
 
 
 -M .1 
 
 
 
 ** 
 
 ft 
 
 a! 
 
 ft 
 
 gjfl 
 
 ft 
 
 as 
 
 ft 
 
 a! 
 
 ft 
 
 a 3 
 
 ft 
 
 al 
 
 
 '53 
 
 g 
 
 7T *c3 
 
 a 
 
 ' 3 
 
 S 
 
 ' g 
 
 a 
 
 " '^ 
 
 a 
 
 '5 g 
 
 
 o 
 
 s 
 
 H 
 
 ^o 
 
 & 
 
 o 
 
 H 
 
 
 1 
 
 ^0 
 
 | 
 
 
 -20 
 
 0.166 
 
 2 
 
 0.529 1 24 
 
 1.483 
 
 40 
 
 3.539 
 
 68 
 
 7.480 
 
 90 
 
 14.790 
 
 19 
 
 0.174 
 
 3 
 
 0.554 
 
 35 
 
 1.551 
 
 47 
 
 3.667 
 
 69 
 
 7.726 
 
 91 
 
 15.234 
 
 18 
 
 0.184 
 
 4 
 
 0.582 
 
 26 
 
 1.623 
 
 48 
 
 3.800 
 
 70 
 
 7.980 
 
 93 
 
 15.C89 
 
 17 
 
 0.196 
 
 5 
 
 0.610 
 
 37 
 
 1.697 
 
 49 
 
 3.936 
 
 71 
 
 8.240 
 
 93 
 
 16.155 
 
 -16 
 
 0.207 
 
 6 
 
 0.639 
 
 28 
 
 1.773 
 
 50 
 
 4.076 
 
 72 
 
 8.508 
 
 94 
 
 16.634 
 
 15 
 
 0.218 
 
 7 
 
 0.671 
 
 29 
 
 1.853 
 
 51 
 
 4.222 
 
 73 
 
 8.782 
 
 95 
 
 17.134 
 
 14 
 
 0.231 
 
 8 
 
 0.704 
 
 30 
 
 1.935 
 
 53 
 
 4.372 
 
 74 
 
 9. 063 
 
 96 
 
 17.626 
 
 13 
 
 0.243 
 
 9 
 
 0.739 
 
 31 
 
 2.022 
 
 53 
 
 4.526 
 
 75 
 
 9.356 
 
 97 
 
 18.142 
 
 12 
 
 0.257 
 
 10 
 
 0.776 
 
 32 
 
 2.113 
 
 54 
 
 4.685 
 
 76 
 
 9.655 
 
 98 
 
 18.671 
 
 11 
 
 0.270 
 
 11 
 
 0.816 
 
 33 
 
 3.194 
 
 55 
 
 4.849 
 
 77 
 
 9.962 
 
 99 
 
 19.213 
 
 10 
 
 0.285 
 
 13 
 
 0.856 
 
 34 
 
 2.279 
 
 56 
 
 5.016 
 
 78 
 
 10.377 
 
 100 
 
 19.766 
 
 9 
 
 0.300 
 
 13 
 
 0.898 
 
 35 
 
 2.366 
 
 57 
 
 5.191 
 
 79 
 
 10.631 
 
 101 
 
 20.335 
 
 8 
 
 0.316 
 
 14 
 
 0.941 
 
 S6 
 
 2.457 
 
 58 
 
 5.370 
 
 80 
 
 10.934 
 
 103 
 
 20.^17 
 
 7 
 
 0.333 
 
 15 
 
 0.986 
 
 37 
 
 2.550 
 
 59 
 
 5.555 
 
 81 
 
 11.275 
 
 103 
 
 21. ,4 
 
 6 
 
 0.350 
 
 16 
 
 1.032 
 
 38 
 
 2.646 
 
 60 
 
 5.745 
 
 83 
 
 11.626 
 
 104 
 
 22.125 
 
 5 
 
 0.370 
 
 17 
 
 1.080 
 
 39 
 
 2.746 
 
 61 
 
 5.941 
 
 83 
 
 11.987 
 
 105 
 
 23.750 
 
 4 
 
 0.389 
 
 18 
 
 1.128 
 
 40 
 
 2.8-19 
 
 62 
 
 6.142 
 
 84 
 
 12.356 
 
 106 
 
 23.393 
 
 3 
 
 0.411 
 
 19 
 
 1.181 
 
 41 
 
 2.955 
 
 63 
 
 6.349 
 
 85 
 
 12.736 
 
 107 
 
 24.048 
 
 3 
 
 0.434 
 
 20 
 
 1.235 
 
 43 
 
 3.061 
 
 64 
 
 6.6C3 
 
 86 
 
 13.127 
 
 108 
 
 24.720 
 
 1 
 
 0.457 
 
 21 
 
 1.294 
 
 43 
 
 3.177 
 
 65 
 
 6.782 
 
 87 
 
 13.526 
 
 109 
 
 25.408 
 
 
 
 0.481 
 
 23 
 
 1.355 
 
 44 
 
 3.294 
 
 66 
 
 7.009 
 
 88 
 
 13.937 
 
 110 
 
 ?6.112 
 
 1 
 
 0.505 
 
 23 
 
 1.418 
 
 45 
 
 3.414 
 
 67 
 
 7.241 
 
 89 
 
 14.359 
 
 
 
 289 
 
TABLE 9. 
 
 Properties of Air With Moisture under Pressure of 
 Atmosphere. * 
 
 
 So 
 
 
 
 X) 
 
 Mixtures of air saturated 
 
 2 
 
 g 
 
 
 Q) O 
 
 >> 
 
 .2^ 
 
 with vapor. 
 
 K 
 
 a 
 
 
 "flrH 
 
 
 
 CLJ 
 
 '" OS 
 
 
 S & 
 
 1 
 
 S^m" 
 
 Weight of cubic 
 
 > 
 
 
 
 o> ~? 
 
 O.S 
 
 O 1 
 
 ^.~ a 
 
 foot of the 
 
 ts 
 
 c 
 +J 
 
 <w 
 
 ^ 
 
 h 
 
 '-3'| 
 
 ^ 72 
 
 Cjf 
 
 J3*^ 
 
 mixture. 
 
 o 
 
 
 c* 
 
 S+j 
 
 & 
 
 "So 
 
 * H ft 
 S 'l 
 
 "8* 
 
 sis 
 
 -a . 
 
 a> ^ 
 
 O 60 
 
 ,0 
 
 S-i 
 
 0) 
 
 '3 
 
 "^ 
 
 &B 
 
 
 
 p 
 
 'S 03 
 
 Cj^j 
 
 gg 
 
 8| 
 
 o.d n 
 
 ^fl 
 
 g| 
 
 3 
 fcflS 
 
 ci 
 t 
 
 s-i ^ 
 
 
 
 S| 
 
 ^1 
 
 -D 
 Oj 
 
 5^ 
 
 
 
 O 0) 
 
 w g 
 
 -s- 
 
 o 
 ft 
 
 fl 
 
 'Z'~ 
 
 <M 
 
 ^ 
 
 O k 
 
 ^of 
 
 SH O 
 
 $g 
 
 <3 
 
 *M 'o 
 
 -M ji> 
 
 o 
 
 O Q^ i( ^ 
 
 4J 
 
 4 *i-H 
 
 0^ 
 
 
 
 
 5 
 
 ft 
 
 0> 
 
 5 
 
 to O 
 
 OJ-*- 1 C 
 
 .2 
 
 Ss 
 
 "3-2 
 
 O 
 
 ofc 
 
 -'s.S 
 
 2-S 
 
 0) 
 
 H 
 
 >$ 
 
 Is 
 
 
 ^ ft 
 
 i'S 
 
 3 a 
 
 
 II 
 
 *. 
 
 C3 
 
 Wfc 
 
 Us 
 
 P C 
 00 
 
 1 
 
 2 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 10 
 
 31 
 
 12 
 
 
 
 .935 nsfii 
 
 0.044 
 
 39.877 
 
 .0863 
 
 .000079 
 
 .086379 
 
 .00092 
 
 1092 40 
 
 48.5 
 
 12 
 
 .960 
 
 .0842 
 
 0.074 
 
 39.849 
 
 .0840 
 
 .000130 
 
 .084130 
 
 .00115 
 
 646 IQi 
 
 50.1 
 
 22 
 
 '.980 
 
 !o824 
 
 0.118 
 
 29! 803 
 
 .0821 
 
 .000202 
 
 1 082302 
 
 .00245 
 
 406.40 
 
 
 51.1 
 
 32 
 
 1.000 
 
 .0807 
 
 0.181 
 
 29.740 
 
 .0802 
 
 .000304 
 
 .080504 
 
 .00379 
 
 263.81 
 
 3289.0 
 
 52.0 
 
 42 
 
 1.020 
 
 .0791 
 
 0.367 
 
 29.654 
 
 .0784 
 
 .000440 
 
 .078840 
 
 .00561 
 
 178.18 
 
 2252.0 
 
 53.2 
 
 52 
 
 1.041 
 
 .0766 
 
 0.388 
 
 29.53? 
 
 .0766 
 
 .000627 
 
 .077227 
 
 .00819 
 
 122.17 
 
 1595.0 
 
 54.0 
 
 80 
 
 1.057 
 
 .0764 
 
 0.522 
 
 29.399 
 
 0751 
 
 .000830 
 
 .075252 
 
 .01251 
 
 92.27 
 
 1227.0 
 
 55.0 
 
 62 
 
 1.061 
 
 .0761 
 
 0.556 
 
 29 365 
 
 .0747 
 
 .000881 
 
 .075581 
 
 .01179 
 
 84.79 
 
 1136.0 
 
 56.2 
 
 70 
 
 1.078 
 
 .0750 
 
 0.75-4:29.182 
 
 .0731 
 
 .001153 
 
 .073509 
 
 .01780 
 
 64.59 
 
 88?. 
 
 f>7.3 
 
 72 
 
 1.083 
 
 .0747 
 
 .0.785 
 
 29.136 
 
 .0727 
 
 .001221 
 
 .073931 
 
 .01680 
 
 59.54 
 
 819.0 
 
 58.5 
 
 82 
 
 1.103 
 
 .0733 
 
 1.099 
 
 28.82C 
 
 .0706 
 
 .001667 
 
 .072267 
 
 .02361 
 
 42.35 
 
 600-0 
 
 58.7 
 
 92 
 
 1.133 
 
 .0720 
 
 1.501 
 
 38.420 
 
 .0684 
 
 .002250 
 
 .070717 
 
 .03289 
 
 30.40 
 
 444.0 
 
 58.9 
 
 100 
 
 1.139 
 
 .0710 
 
 1.929 
 
 2r.99 
 
 .0664 
 
 .0028-18 
 
 .069261 
 
 .04495 
 
 23.66 
 
 356.0 
 
 59.1 
 
 103 
 
 1.143 
 
 .0707 
 
 2.036 
 
 27.885 
 
 .0653 
 
 .002997 
 
 .068897 
 
 .04547 
 
 2] .98 
 
 334.0 
 
 59.5 
 
 112 
 
 1.163 
 
 .0694 
 
 2.731 
 
 37.190 
 
 .0631 
 
 .003946 
 
 .067042 
 
 .06253 
 
 15.99 
 
 353.0 
 
 60.6 
 
 122 
 
 1.184 
 
 .0682 
 
 3.621 
 
 26.300 
 
 .0599 
 
 .005142 
 
 .065046 
 
 .08584 
 
 11.65 
 
 194.0 
 
 61.7 
 
 132 
 
 1.204 
 
 .0671 
 
 4.752 
 
 25.169 
 
 .0564 
 
 .OC6639 
 
 .063039 
 
 .11771 
 
 8.49 
 
 151.0 
 
 62.5 
 
 142 
 
 1.224 
 
 .0660 
 
 6.165 
 
 23.756 
 
 .0534 
 
 .008473 
 
 .060873 
 
 .16170 
 
 6.18 
 
 118.0 
 
 63.7 
 
 152 
 
 1.245 
 
 .0649 7.930 
 
 21.991 
 
 .0477 
 
 .010710 
 
 .058416 
 
 .22465 
 
 4.45 
 
 93.3 
 
 65.0 
 
 162 
 
 1.265 
 
 .0638 
 
 10.099 
 
 19.823 
 
 .0423 
 
 .013415 
 
 .055715 
 
 .31713 
 
 3.15 
 
 74.5 
 
 66.1 
 
 172 
 
 1.285 
 
 .0628 
 
 12.758 
 
 17.163 
 
 .0360 
 
 .016682 
 
 .052682 
 
 .46338 
 
 2.16 
 
 59.2 
 
 67.1 
 
 182 
 
 1.306 
 
 .0618115.960 
 
 13.961 
 
 .0288 
 
 .020536 
 
 .049336 
 
 .71300 
 
 1.402 
 
 48.6 
 
 68.0 
 
 192 
 
 1.326 
 
 .06Q9;19.828 
 
 10.093 
 
 .0205 
 
 .025142 
 
 .045642 
 
 1.22643 
 
 .815 
 
 39.8 
 
 68.9 
 
 202 
 
 1.347 
 
 .0600 
 
 24.450 
 
 5.471 
 
 .0109 
 
 .030545 
 
 .041445 
 
 2.80230 
 
 .357 
 
 82.7 
 
 70.2 
 
 212 
 
 1.367 
 
 .0591 
 
 29.931 
 
 0.000 
 
 .0000 
 
 .038820 
 
 .036320 
 
 finite 
 
 .000 
 
 27.1 
 
 71.4 
 
 "Carpenter's H. & V. B. and Sturtevant's Mech. Draft. 
 
 290 
 
(I) 
 Q 
 
 s i 
 
 I i 
 
 hi 
 
 21 S 
 
 155 
 
 niiiiiiiiiiiiiiiiiiiiii 
 
 291 
 
TABLE 11. 
 Fuel Value of American Coals.* 
 
 COAL, 
 Name or Locality. 
 
 Fuel Value per Pound 
 of Coal. 
 
 B. t.u. 
 calculated. 
 
 B.'t.u. by 
 calorimeter. 
 
 Theoretical evap- 
 oration in Ibs. 
 from and at 
 
 212 F 
 
 ARKANSAS. 
 Spadra, Johnson Co 
 
 14,420 
 
 9,215 
 
 13,560 
 8,500 
 
 14,020 
 13,097 
 
 14,391 
 15,198 
 9,326 
 
 13,714 
 13,414 
 
 14,199 
 13,300 
 
 14,200 
 
 11,813 
 11,756 
 
 11,781 
 9,035 
 9,739 
 13,123 
 
 8,703 
 
 9,890 
 11,756 
 
 13,104 
 12,936 
 
 9,450 
 12,963 
 
 14,373 
 
 14.90 
 12.23 
 12.17 
 9.54 
 
 14.04 
 8.80 
 
 13.19 
 9.35 
 10.09 
 13.68 
 
 14.50 
 13.56 
 
 9.01 
 
 14.89 
 16.76 
 9.65 
 
 10.24 
 13.17 
 
 14.30 
 13.90 
 
 14.70 
 12.73 
 13.46 
 13.39 
 
 9.78 
 13.41 
 
 14.71 
 14.70 
 
 Coal Hill, Johnson Co. 
 
 Huntington Co. 
 
 Lignite _ 
 
 COLORADO. 
 Lignite 
 
 Lignite slack 
 
 ILLINOIS. 
 Big Muddy, Jackson Co 
 
 Colchester, Slack 
 
 Giliespie, Macoupin Co. 
 
 Mercer Co. 
 
 INDIANA. 
 Block 
 
 Cannel . 
 
 IOWA. 
 
 Good cheer 
 
 KENTUCKY. 
 Caking _ __ 
 
 Cannel 
 
 Lignite 
 
 MISSOURI. 
 Bevier Mines 
 
 NEW MEXICO. 
 Coal 
 
 OHIO. 
 Briar Hill, Mahoning Co. 
 
 Hocking Valley 
 
 PENNSYLVANIA. 
 Anthracite 
 
 Anthracite, pea 
 
 Pittsburgh (average) 
 
 Youghiogheney 
 
 TEXAS". 
 
 Port Worth 
 
 Lignite 
 
 WEST VIRGINIA. 
 Pocahontas 
 
 New River _ __ _ 
 
 
 *Sturtevant's "Mechanical Draft." 
 
 292 
 
TABLE 12. 
 Capacities of Chimneys,* 
 
 Inside Diameter of 
 Lined Flue 
 (Inches) 
 
 
 Maximum Sq. Ft. of Cast-iron Radiating 
 Surface and B. t. u. for a Flue of the 
 Given Diameter and Height. 
 
 | 
 
 W 
 
 ,cj 
 
 to 
 
 i 
 
 a 
 
 be 
 
 5 
 
 i 
 
 W 
 
 ,a 
 &o 
 
 a 
 
 i 
 w 
 
 3 
 
 & 
 
 3 
 
 3 
 
 00 
 
 
 
 6 
 7 
 8 
 9 
 10 
 12 
 15 
 18 
 
 Steam 
 
 146 
 243 
 
 36500 
 
 228 
 379 
 
 57000 
 
 327 
 544 
 
 81750 
 
 445 
 742 
 111250 
 
 582 
 969 
 145500 
 
 909 
 1514 
 227250 
 
 1537 
 2561 
 
 334250 
 
 2327 
 
 3878 
 581750 
 
 175 
 291 
 
 43750 
 
 273 
 455 
 68250 
 
 392 
 653 
 
 98000 
 
 534 
 890 
 133500 
 
 698 
 1163 
 
 174500 
 
 1090 
 1817 
 
 272500 
 
 1844 
 3073 
 461000 
 
 2792 
 4653 
 698000 
 
 204 
 
 340 
 51000 
 
 319 
 531 
 
 79750 
 
 457 
 
 763 
 114250 
 
 623 
 1038 
 155750 
 
 814 
 1357 
 203500 
 
 1272 
 2120 
 318000 
 
 2151 
 
 3586 
 537750 
 
 3257 
 5429 
 814250 
 
 233 
 
 388 
 58250 
 
 364 
 
 607 
 91000 
 
 523 
 871 
 
 130750 
 
 712 
 
 1187 
 
 178000 
 
 930 
 1551 
 
 232500 
 
 1454 
 2423 
 363500 
 
 2458 
 4098 
 614500 
 
 3722 
 6204 
 930500 
 
 262 
 437 
 65500 
 
 410 
 683 
 102500 
 
 588 
 980 
 147000 
 
 801 
 1335 
 200250 
 
 1047 
 1745 
 261750 
 
 1636 
 2726 
 409000 
 
 2766 
 4610 
 691500 
 
 4188 
 6980 
 1047000 
 
 291 
 
 485 
 72750 
 
 455 
 
 758 
 113750 
 
 653 
 
 1088 
 163250 
 
 890 
 1483 
 
 222500 
 
 1163 
 1938 
 290750 
 
 1817 
 3028 
 454250 
 
 3073 
 5122 
 
 768250 
 
 4653 
 7755 
 1163250 
 
 Hot Water 
 B. t. u. ___ 
 
 Steam _. _ 
 
 Hot Water 
 
 B. t. u. _ _ _ 
 
 Steam 
 
 Hot Water . 
 
 B. t. u. ___ _ 
 
 Steam 
 
 Hot Water 
 
 B. t. u. 
 
 Steam 
 
 Hot Water 
 
 B. t. u. 
 
 Steam 
 
 Hot Water 
 B. t. u. 
 
 Steam _-.___ 
 
 Hot Water 
 B. t. u. 
 
 Steam _ 
 
 Hot Water. __ 
 B. t. u - 
 
 
 
 Radiation is calculated at 250 B. t. u. steam, 150 B. t. u. water. 
 
 *The Model Boiler Manual. 
 
 293 
 
TABLE 13. 
 Equalization of Smoke Flues Commercial 
 
 Inside 
 Diameter 
 Lined Flue 
 
 Brick Flue 
 Not Lined 
 Well Built 
 
 Rectangular 
 Lined Flue 
 Outside of Tile 
 
 Outside 
 Iron 
 Stack 
 
 6 
 7 
 8 
 9 
 10 
 13 
 15 
 18 
 
 8%x8% 
 
 8y 2 x8y 2 
 8y 2 x8y 2 
 
 8V 2 xl3 
 8y 2 xl3 
 13x13 
 13x17 
 17x21 %j 
 
 7x7 
 8y 2 x8y 2 
 8^x13 
 8V 2 X13 
 13x13 
 13x18 
 18x18 
 
 8 
 9 
 10 
 
 11 
 
 12 
 14 
 17 
 20 
 
 Round Flue Tile Lining 1 is listed by its inside measurement. 
 Rectangular Lining 1 by outside Measurement. 
 
 TABLE 11 
 Dimensions of Registers.* 
 
 Size of 
 opening, 
 Inches 
 
 Nominal 
 area of 
 opening, 
 Square 
 Inches 
 
 Effective 
 area of 
 opening, 
 Square 
 Inches 
 
 Tin Box Size, 
 Inches 
 
 Extreme 
 dimensions of 
 register face, 
 Inches 
 
 6x10 
 
 60 
 
 40 
 
 63 
 
 ' x 10 T 9 5 
 
 7jl x lljj 
 
 8x10 
 
 80 
 
 53 
 
 85 
 
 i x 10H 
 
 
 8x12 
 
 96 
 
 64 
 
 
 /8 X 12% 
 
 9% x 13K 
 
 8x15 
 
 120 
 
 80 
 
 85 
 
 8 X 15% 
 
 9K x 1615 
 
 9x12 
 
 108 
 
 72 
 
 91 
 
 5 x 12JS 
 
 IOH x 13% 
 
 9x14 
 
 126 
 
 84 
 
 9] 
 
 4 x 14H 
 
 10% x 16# 
 
 10x12 
 10x14 
 10x16 
 
 120 
 140 
 160 
 
 80 
 93 
 107 
 
 1014 x I2\l 
 101J x 1614 
 
 llli x 1318 
 1118 x 1518 
 1118 x 17% 
 
 12x15 
 
 180 
 
 120 
 
 123 
 
 4x15% 
 
 14^ x 17 
 
 12x19 
 
 228 
 
 152 
 
 12; 
 
 
 14^ x 21 
 
 14x22 
 
 308 
 
 205 
 
 14, 
 
 4 x 22% 
 
 16*4 x 24^ 
 
 15x25 
 
 375 
 
 250 
 
 15, 
 
 /sx25% 
 
 
 16x20 
 
 320 
 
 218 
 
 16 
 
 ft x 20% 
 
 18 T 5 S x 22A 
 
 16x24 
 
 384 
 
 256 
 
 16, 
 
 ft x24% 
 
 ISA x 22& 
 
 20x20 
 
 400 
 
 267 
 
 2018 x 2018 
 
 22% x 22% 
 
 20x24 
 
 480 
 
 820 
 
 20, 
 
 8 x 241 i 
 
 22% x 26% 
 
 20x26 
 
 520 
 
 347 
 
 20 
 
 8 x 2618 
 
 22% x 28% 
 
 21x29 
 
 609 
 
 403 
 
 21 
 
 8 x 2918 
 
 28% x 81% 
 
 27x27 
 
 729 
 
 486 
 
 27- 
 
 8x2718 
 
 29% x 29% 
 
 27x38 
 80x30 
 
 1026 
 900 
 
 684 
 600 
 
 27- 
 80 
 
 8x3818 
 8 x 3018 
 
 29% x 403/g 
 32% x 32% 
 
 Dimensions of different makes of registers vary slightly, Th 
 above are for Tuttle & Bailey Manufacturing Oo.'s manufacture. 
 
 *The Model Boiler Manual. 
 
 94 
 
TABLE 15. 
 
 Specific Heats, Coefficients of Expansion, Coefficients of Trans- 
 mission, and Fuslng-Points of Solids, Liquids or Gases.* 
 
 SUBSTANCE. 
 
 o 
 
 2* 
 
 C> 5? 
 
 jM 
 
 Coefficient of 
 Expansion. 
 
 Coefficient of 
 Transmission 
 
 Fusion Points 
 Degrees 
 
 Antimony 
 
 0.0508 
 0.0951 
 0.0324 
 0.1138 
 0.1937 
 0.1298 
 0.0314 
 0.0324 
 0.0570 
 0.0562 
 0.1165 
 0.1175 
 
 .00000602 
 .00000955 
 
 .00001060 
 .00000895 
 .00000478 
 .00000618 
 .00001580 
 .00000530 
 .00001060 
 .00001500 
 .00000600 
 .00000689 
 .00000003 
 .00001633 
 .00001043 
 .00000375 
 .00006413 
 .00007860 
 .00002313 
 .00012530 
 .00006806 
 .00003333 
 .00015151 
 
 .00022 
 .00404 
 
 815 
 
 1949 
 1947 
 2975 
 1832 
 2192 
 621 
 3452 
 1751 
 446 
 2507 
 2507 
 
 "787 
 1859 
 32 
 
 Copper 
 
 Gold . 
 
 Wrought Iron 
 Glass 
 
 .00089 
 .0000008 
 .000659 
 .00045 
 
 Cast Iron 
 
 Lead 
 
 Platinum 
 
 Silver 
 
 .00610 
 .00084 
 .00062 
 .00034 
 
 Tin . 
 
 Steel (soft) 
 
 Steel (hard) 
 
 Nirkel steel 36% 
 
 Zinc 
 
 0.0956 
 0.0939 
 0.5040 
 0.2026 
 0.2410 
 0.1970 
 0.1887 
 1.0000 
 0.0333 
 0.7000 
 
 .00170 
 .00142 
 .000024 
 
 "660602 
 
 .00203 
 
 "ooooos 
 
 .00011 
 .000000 
 
 Brass 
 
 Ice 
 
 Sulphur 
 
 Charcoal 
 
 1213 
 
 Aluminum _ 
 
 Phosphorus 
 
 Water 
 
 Mercury 
 
 :::: 
 
 Alcohol (absolute) 
 
 
 Con- 
 stant 
 Pres- 
 sures 
 
 Con- 
 stant 
 volume 
 
 Coefficient 
 of cubical ex- 
 pansion at 1 
 atmos. 
 
 
 Air 
 
 0.23751 
 0.21751 
 
 3.40900 
 0.24380 
 0.4805 
 0.2170 
 
 0.16847 
 0.15507 
 2.41226 
 0.17273 
 0.346 
 0.1535 
 
 .003671 
 .003674 
 .003669 
 .003668 
 .003726 
 
 .0000015 
 
 .0000012 
 .0000012 
 .0000012 
 
 "60006120 
 
 
 
 Oxygen 
 
 Hydro gen 
 
 Nitrogen 
 
 Superheated Steam 
 Carbonic Acid 
 
 "Kent and Suplee. 
 
 295 
 
TABLE 16. 
 
 Capacities of \Varm Air Furnaces of Ordinary Construction 
 Cubic Feet of Space Heated.* 
 
 Divided Space 
 
 Fire Pot 
 
 Undivided Space 
 
 +10 
 
 
 
 10 
 
 Diam. 
 
 Area 
 
 + 10 
 
 
 
 -10 
 
 12000 
 
 10000 
 
 8000 
 
 18 in. 
 
 1.8 sq. ft. 
 
 17000 
 
 14000 
 
 12000 
 
 14000 
 
 12000 
 
 10000 
 
 20 
 
 2.2 
 
 22000 
 
 17000 
 
 14000 
 
 17000 
 
 14000 
 
 12000 
 
 22 
 
 2.6 
 
 26000 
 
 22000 
 
 17000 
 
 22000 
 
 18000 
 
 14000 
 
 24 
 
 3.1 
 
 30000 
 
 -26000 
 
 22000 
 
 26000 
 
 22000 
 
 18000 
 
 26 
 
 3.7 
 
 85000 
 
 30000 
 
 26000 
 
 30000 
 
 26000 
 
 22000 
 
 28 
 
 4.8 
 
 40000 
 
 35000 
 
 30000 
 
 35000 
 
 30000 
 
 26000 
 
 30 
 
 4.9 
 
 50000 
 
 40000 
 
 35000 
 
 TABLE 17 
 Capacities of Hot-Air Pipes and Registers. 
 
 
 ^ 
 
 fl f-> 
 
 M-t->j 
 
 
 
 a 
 
 h 
 
 <U 
 
 '"-$ 
 
 
 ^ 
 
 o 
 
 
 
 la 
 
 2 
 
 13 
 
 
 
 
 
 
 ' 
 
 *""* 
 
 
 CJ ^ C) 
 
 ft o 
 
 
 
 1 
 
 a t-> 
 
 S** 
 ^ 
 
 w o 9 
 
 *5 
 
 H 
 
 R 
 
 2 
 
 
 3 
 
 53 
 
 O 
 
 w 
 
 
 "eS & 
 
 09 
 
 
 c 
 
 1 
 
 III 
 
 H 80, 
 
 > . 
 
 Ill 
 
 O cc^ js 
 
 5iD 
 S 
 
 11 
 
 6x8 
 
 6 in. 
 
 4x8 
 
 400 
 
 450 
 
 500 
 
 8x8 
 
 7 " 
 
 4x10 
 
 450 
 
 500 
 
 560 
 
 8x10 
 
 8 " 
 
 4x10 
 
 500 
 
 850 
 
 880 
 
 8x13 
 
 8 " 
 
 4x11 
 
 800 
 
 1000 
 
 1050 
 
 9x13 
 
 9 " 4x12 
 
 1050 
 
 1250 
 
 1324 
 
 9x14 
 
 9 " 
 
 4x14 
 
 1050 
 
 1350 
 
 1450 
 
 10x13 
 
 10 " 
 
 4x14 
 
 1500 
 
 1650 
 
 1800 
 
 10X14 
 
 10 " 
 
 6x10 
 
 1800 
 
 2000 
 
 2200 
 
 10x16 
 
 10 " 
 
 6x10 
 
 1800 
 
 2000 
 
 2200 
 
 12x14 
 
 12 " 
 
 6x12 
 
 2200 
 
 2300 
 
 2500 
 
 12x15 
 
 12 " 
 
 6x12 
 
 2250 
 
 2300 
 
 2500 
 
 12x17 
 
 12 " 
 
 6x14 
 
 2300 
 
 2600 
 
 2800 
 
 12x19 
 
 12 " 
 
 6x14 
 
 2300 
 
 2600 
 
 2800 
 
 14x18 
 
 14 " 
 
 6x16 
 
 2800 
 
 3000 
 
 3200 
 
 14x20 
 
 14 " 
 
 6x16 
 
 2900 
 
 3000 
 
 3200 
 
 14x22 
 
 14 " 
 
 8x16 
 
 3000 
 
 3200 
 
 3400 
 
 16x20 
 
 16 " 
 
 8x18 
 
 3600 
 
 4000 
 
 4250 
 
 16x24 
 
 16 " 
 
 8x18 
 
 3700 
 
 4000 
 
 4250 
 
 20x24 
 
 18 " 
 
 10x20 
 
 4800 
 
 5400 
 
 5750 
 
 20x26 
 
 20 " 
 
 10x24 
 
 6000 
 
 7000 
 
 7450 
 
 Federal Furnace League Handbook. 
 tKidder's Arch and B'ld'rs Poclcet-Book. 
 
 296 
 
TABLE 18. 
 Air Heating: Capacity of Warm Air Furnaces.* 
 
 Fire Pot 
 
 Casing 
 
 Total cross 
 sec. area of 
 heat pipes 
 
 No. and size of heat pipes that 
 may be supplied 
 
 Diam. 
 
 Area 
 
 Diam. 
 
 
 
 18 i 
 20 
 
 i. 
 
 1.8 iq. 
 
 2.2 * 
 
 ft. 
 
 30"-32" 
 34"-36" 
 
 180 sq 
 
 280 
 
 ( in. 
 
 3-9" or 4-8" 
 2-10" and 2-9" or 3-9" and 2-8" 
 
 22 
 
 
 2.6 
 
 
 86' '-40" 
 
 360 
 
 
 3-10" and 2-9" or 4-9" and 2-8" 
 
 24 
 
 
 3.1 
 
 
 4011.4411 
 
 470 
 
 
 3-10", 1-9" and 2-8" or 2-10" and 5-8" 
 
 26 
 
 
 3.7 
 
 
 44"-50" 565 
 
 
 5-10 and 3-9 or 3-10 , 4-9 and 2-8 
 
 28 
 
 
 4.3 
 
 
 48"-56" 
 
 650 
 
 
 2-12 , 3-10 and 3-9 or 5-10 , 3-9 and 2-8 
 
 30 
 
 
 4.9 
 
 
 52' '-60" 
 
 730 
 
 
 3-12 ,3-10 and 3-9 or 5- 10 ,5-9 and 1-8 
 
 TABLE 19. 
 
 Sectional Area (Sq. Inches) of Vertical Hot Air Flues, Natural 
 Draft, Indirect System.f 
 
 Outside Temjperature 50 F. Flue Temperature 90 F. 
 
 
 STEAM 
 
 WATER 
 
 Sq. Ft. 
 
 
 
 Cast- Iron 
 
 
 
 
 
 
 
 
 
 Radiation 
 
 
 rd 
 
 
 ^ 
 
 
 <O 
 
 
 ,- 
 
 
 ^ 
 
 O f-i 
 
 "Sb 
 
 tJ> 
 
 mtt 
 
 0^ 
 
 2b 
 
 ? 
 
 
 O 
 
 
 33 
 
 
 
 S 
 
 o o 
 
 2 
 
 -2 
 
 
 faze 
 
 O2O2 
 
 HflQ 
 
 fa72 
 
 
 Vll/1 
 
 
 faO2 
 
 to 50 
 
 TOO 
 
 75 
 
 63 
 
 60 
 
 75 
 
 63 
 
 60 
 
 60 
 
 60 75 
 
 150 
 
 113 
 
 94 
 
 80 
 
 113 
 
 94 
 
 80 
 
 80 
 
 75 100 
 
 200 
 
 150 
 
 125 
 
 100 
 
 150 
 
 125 
 
 100 
 
 100 
 
 100 125 
 
 250 
 
 188 
 
 156 
 
 125 
 
 188 
 
 156 
 
 125 
 
 125 
 
 12o 150 
 
 300 
 
 225 
 
 188 
 
 150 
 
 225 
 
 188 
 
 150 
 
 150 
 
 150 175 
 
 350 
 
 263 
 
 219 
 
 175 
 
 263 
 
 219 
 
 175 
 
 175 
 
 175 200 
 
 400 
 
 300 
 
 250 
 
 200 
 
 300 
 
 250 
 
 200 
 
 200 
 
 200 225 
 
 450 
 
 338 
 
 281 
 
 225 
 
 338 
 
 281 
 
 225 
 
 225 
 
 225 250 
 
 500 
 
 375 
 
 313 
 
 250 
 
 375 
 
 313 
 
 250 
 
 250 
 
 250 275 
 
 550 
 
 413 
 
 344 
 
 275 
 
 413 
 
 344 
 
 275 
 
 275 
 
 275 300 
 
 600 
 
 450 
 
 375 
 
 300 
 
 450 
 
 375 
 
 303 
 
 300 
 
 300 325 
 
 650 
 
 488 
 
 406 
 
 325 
 
 488 
 
 406 
 
 325 
 
 325 
 
 325 350 
 
 700 
 
 525 
 
 438 
 
 350 
 
 525 
 
 438 
 
 350 
 
 350 
 
 350 375 
 
 750 
 
 563 
 
 469 
 
 375 
 
 563 
 
 469 
 
 375 
 
 375 
 
 375 400 
 
 800 
 
 600 
 
 500 
 
 400 
 
 600 
 
 500 
 
 400 
 
 400 
 
 Velocity 
 Feet Per Sec. 
 
 * 
 
 
 
 * 
 
 * 
 
 1% 
 
 
 
 4 
 
 4 
 
 Effective Area 
 
 
 
 
 
 
 
 of Register 
 
 1.00 
 
 1.50 
 
 1.83 2.17 1.00 
 
 1.00 
 
 1.33 
 
 1.33 
 
 Factor for 
 
 
 
 
 
 
 
 *Federal Furnace League Handbook. 
 tThe Model Boiler Manual. 
 
 297 
 
TABLE 20. 
 
 Pressure, in Ounces, per Square Inch Corresponding to 
 Various Heads of Water, in Inches.* 
 
 
 Decimal Parts of an Inch. 
 
 Head 
 
 
 in 
 
 
 inches. 
 
 
 
 
 
 
 
 
 
 
 
 
 .0 
 
 .1 
 
 .2 
 
 .3 
 
 .4 
 
 .5 
 
 .6 
 
 .7 
 
 .8 
 
 .9 
 
 
 
 
 .06 
 
 .12 
 
 .17 
 
 .23 
 
 .29 
 
 .35 
 
 :40 
 
 .46 
 
 .52 
 
 1 
 
 .58 
 
 .63 
 
 .69 
 
 .75 
 
 .81 
 
 .87 
 
 .93 
 
 .98 
 
 1.04 
 
 1.00 
 
 2 
 
 1.16 
 
 1.21 
 
 1.27 
 
 1.33 
 
 3.39 
 
 1.44 
 
 1.50 
 
 1.56 
 
 1.62 
 
 1.67 
 
 3 
 
 1.73 
 
 1.79 
 
 1.85 
 
 1.91 
 
 1.96 
 
 2.02 
 
 2.08 
 
 2.14 
 
 2.19 
 
 2.25 
 
 4 
 
 2.31 
 
 2.37 
 
 2.42 
 
 2.48 
 
 2.54 
 
 2.60 
 
 2.66 
 
 2.72 
 
 2.77 
 
 2.83 
 
 6 
 
 2.89 
 
 2.94 
 
 3.00 
 
 3.06 
 
 3.12 
 
 3.18 
 
 3.24 
 
 3.29 
 
 3.3J 
 
 3.41 
 
 6 
 
 3.47 
 
 3.52 
 
 3.58 
 
 3.64 
 
 3.70 
 
 3.75 
 
 3.81 
 
 3.87 
 
 3.92 
 
 3.98 
 
 7 
 
 4.04 
 
 4.10 
 
 4.16 
 
 4.221 
 
 4.28 
 
 4.33 
 
 4.39 
 
 4.45 
 
 4.50 
 
 4.56 
 
 8 
 
 4.62 
 
 4.67 
 
 4.73 
 
 4.79 
 
 4.85 
 
 4.91 
 
 4.97 
 
 5.03 
 
 5.08 
 
 5.14 
 
 9 
 
 5.20 
 
 5.26 
 
 5.31 
 
 5.37 
 
 5.42 
 
 5.48 
 
 5.54 
 
 5.60 
 
 5.66 
 
 5.72 
 
 TABLE 21. 
 
 Height of Water Column, in Inches Corresponding to Pres- 
 sures, in Ounces, per Square Inch.* 
 
 Pressure 
 in ounces 
 
 Decimal Parts of an Ounce. 
 
 >^ Q\J14O..LC; 
 
 inch. 
 
 .0 
 
 ,1 
 
 .2 
 
 .3 
 
 .4 
 
 .5 
 
 .6 
 
 .7 
 
 .8 
 
 .9 
 
 
 
 
 .17 
 
 .35 
 
 .52 
 
 .69 
 
 .87 
 
 1.04 
 
 1.21 
 
 1.38 
 
 1.56 
 
 l 
 
 1.73 
 
 1.90 
 
 2.08 
 
 2.25 
 
 2.42 
 
 2.60 
 
 2.77 
 
 2.94 
 
 3.11 
 
 3.29 
 
 2 
 
 3.48 
 
 3.63 
 
 3.81 
 
 3.98 
 
 4.15 
 
 4.33 
 
 4.50 
 
 4.67 
 
 4.84 
 
 5.01 
 
 3 
 
 5.19 
 
 5.36 
 
 5.54 
 
 5.71 
 
 5.88 
 
 6.06 
 
 6.23 
 
 6.40 
 
 6.57 
 
 6.75 
 
 4 
 
 6.92 
 
 7.09 
 
 7.27 
 
 7.44 
 
 7.61 
 
 7.79 
 
 7.96 
 
 8.13 
 
 8.30 
 
 8.48 
 
 5 
 
 8.65 
 
 8.82 
 
 9.00 
 
 9.17 
 
 9.34 
 
 9.52 
 
 9.69 
 
 9.86 
 
 10.03 
 
 10.21 
 
 6 
 
 10.38 
 
 10.55 
 
 10.73 
 
 10.90 
 
 11.07 
 
 11.26 
 
 11.43 
 
 11.60 
 
 11.77 
 
 11.95 
 
 7 
 
 12.11 
 
 12.28 
 
 12.46 
 
 12.63 
 
 12.80 
 
 12.97 
 
 13.15 
 
 13.32 
 
 13.49 
 
 13.67 
 
 8 
 
 13.84 
 
 14.01 
 
 14.19 
 
 14.36 
 
 14.53 
 
 14.71 
 
 14.88 
 
 15.05 
 
 15.22 
 
 15.40 
 
 9 
 
 15.57 
 
 15.74 
 
 15.92 
 
 16.09 
 
 16.20 
 
 16.45 
 
 16.62 
 
 16.70 
 
 16.96 
 
 17.14 
 
 *Suplee's M. E. Reference Book. 
 
 298 
 
JOO j 
 
 M j^ 9 
 
 MrtrHiHrHiHrHiHCOWOOCOOOOOWCOGOOOOOOOOOOOOOOOOOOO 
 
 jooj lad 
 
 looj Diqno 
 
 13 
 
 ~ - 
 
 i S co 3> ' 
 
 * tt M * 8> 1-4 r-l IH 
 
 b S 
 
 Oi <?i CO fc- ' 
 
 -^ & o GQ 
 
 U 
 
 t~ O C<> C^ Ci CO rH 
 
 xoaddy 
 
 
 
 299 
 
TABLE 23. 
 Expansion of Wrought-Iron Pipe on the Application of Heat.* 
 
 Tern p. Air 
 
 When 
 
 Pipe 
 
 is Fitted. 
 
 Increase in Length in Inches Per 100 Feet 
 When Heated to 
 
 Degrees 
 
 160 
 
 180 
 
 200 
 
 212 
 
 220 
 
 228 
 
 240 
 
 274 
 
 Fahr. 
 
 
 
 
 
 
 
 
 
 
 
 1.28 
 
 1.44 
 
 1.60 
 
 1.70 
 
 1.76 
 
 1.82 
 
 1.93 
 
 2.19 
 
 32 
 
 1.02 
 
 1.18 
 
 1.34 
 
 1.44 
 
 1.50 
 
 1.57 
 
 1.66 
 
 1.94 
 
 50 
 
 .88 
 
 1.04 
 
 1.20 
 
 1.30 
 
 1.36 
 
 1.42 
 
 1.52 
 
 1.79 
 
 70 
 
 .72 
 
 .88 
 
 1.04 
 
 1.14 
 
 1.20 
 
 1.26 
 
 1.36 
 
 1.63 
 
 TABLE 24. 
 Tapping: List of Direct Radiators.f 
 
 STEAM. 
 
 ONE-PIPE WORK. 
 
 TWO-PIPE WORK. 
 
 Radiator Area. 
 Square Feet. 
 
 Tapping Diam- 
 eter. Inches. 
 
 Radiator Area. 
 Square Feet. 
 
 Tapping Diam- 
 eter. Inches. 
 
 24 
 24 60 
 60 100 
 100 and above 
 
 1 
 
 l!4 
 
 I* 
 
 48 
 48 96 
 96 and above 
 
 1 x % 
 114x1 
 l%xl% 
 
 WATER. 
 Tapped for* Supply and Return. 
 
 Radiator Area. 
 Square Feet. 
 
 Tapping Diameter. 
 Inches. 
 
 40 
 40 72 
 72 and above. 
 
 1 
 VA 
 
 1% 
 
 *Holland Heating Manual, 
 t American Radiator Co. 
 
 300 
 
TABLE 25. 
 Pipe Equalization. 
 
 This table shows the relation of the 
 
 combined area of small round warm air w ,-< <* eo M us us *> * 
 
 ducts or pipes to the area of one ^ *! 2S^ 
 
 large main duct. S^2 rn'rHiHiHiH rH^e* 
 
 The bold figures at the top of the ,_ H <s >* us <o t- cs o -j 
 
 column represent the diameters ^^^^ ^^^^^ 
 
 ,. , r 11 OrHeO^ iOD5<3Sr-l CO 
 
 of the small pipes or ducts; ^^^^^^^^^eiwd** 
 
 those in the left-hand vertical ^e^ust-cco^^co 
 
 columns are the diameters of "rn'r-l^r-iMM^ciwdoid&i 
 
 the main pipes. The small ^ *-; e*coinot> os <=>>* us t-osr-i 
 
 figures show the number ~ *&$* ***** 
 
 of small pipes that each S_;_; ^ ^ ,_; .H' .-J tec4te 
 main duct will supply. 
 
 , _. ,. 
 
 h.xample. 1 o supply six- 
 teen 10-inch pipes: Refer 
 
 to column having 10 at top; e ^eo^ob: esrHtoia smuat^e wooq 
 
 follow down to small "^ IH I-H r4 rn ^ McioJoid >* ^^^ 
 
 ficure 1 6 thence left on 1 *.<* . *. .** . ! . **:*.' . ^ ^ 
 
 iiguic i y, ui iicc icu on t ~rHrH r nrHrHc4e&Jc4WM<>iieo^^ivft'> 
 
 the horizontal line or e3 co^t-oorHc4iot--oMcooj-*Qqi 
 
 the bold-face figure IH rn rn'M^dsi <SMWM co^^^ui 
 
 in the outside col- ^ K - " ^ . 'I ^. J 1 ^ ^ ^ ? *. *. ^ 
 
 j c j * t-i i-i rJ rJ IH i oi e w * ^T"* e o 
 
 umn, and we find ^ so 10 1- o * o IH * o r-j ^* t- rn i> o * i-j 
 
 that one 30-inch - r4 4i4 IH ei e eo '*'*-* uj 10 to o i> z> t> ed 
 
 mam will sup- m e>i * & oq r-j eoiDCONio ocooooit- T-J us i-j so <* 
 
 ply air for ^THrHrHrHd<^e4eoeo'*-*'*io>ooeDi>>a3 
 
 * "*OO3C4i COrH^OOlS t- T-) b- t- "HOiOrHO 
 
 the sixteen ^ H t4 r40j co eo <* -* 10 ia 5 co ^ 06 06 d M 
 
 1 - inch M**^ t-ooooi cQt>r-HO i> r-j oq e "^^SSS 
 
 oioes ''"'"^rH iHcie^ei^i coM-<f!-*ia ta <> <D t> ad ooos 
 
 c^ c* 'ft co r-j-^oqe^o i-jvisot--^ as o so IH os OI-HNSO-* oooo 
 
 *~iHrH,_; Nuieicoeo' rji^ujiaco 6i>o6osc> ^ 
 
 ^_ e<i us co K s -* o us 6Je-<DO es o TH ^useo ggg^ 
 *" rt r4 ?H <(J 1 " 1 ' 
 
 D os s co 
 
 ^- ^ ^ ^ (jj (4 CO CO * US ITS O Z> t- 
 
 co t><SU50O NOsi>u5rij -*cO 
 
 01 rH T-ieifiievSCO -^Wiu5Ot> 00(35 
 
 b- N^rHoq t-cot-.eocs oco 
 
 *",_,,_, (jJoiCOrJH^ USCOt-0001 
 
 
 i-i IH 04 coco^ioo j> a> 
 
 us 
 
 IH 
 
 . 
 
 t-H CO * US t- OS 
 
 ss ^ c?c5^^S gSS; IgSSS ISI1I I 
 
 i^s s^^sg mil iii|S ig||| | 
 
 lllil 
 
 S2*SS 51 
 
 ^t- m to i oo CD o - 
 
 
 SSSS 
 
 
 301 
 
TABLE 26. 
 
 Capacities of Hot \Vater Risers in Square Feet of Direct 
 Radiation.* 
 
 Drop in Temperature 20. 
 
 D. of 
 
 
 
 
 
 
 
 Riser 
 
 1 F'l. 
 
 2 PI. 
 
 3 Fl. 
 
 4 Fl. 
 
 5 Fl. 
 
 6 Fl. 
 
 Inches. 
 
 
 
 
 
 
 
 % 
 
 32 
 
 IT 
 
 21 
 
 24 
 
 
 
 ] 
 
 22 
 
 32l 
 
 40 
 
 48 
 
 
 
 i*/i 
 
 38 
 
 56 
 
 70 
 
 80 
 
 88 
 
 
 iy 2 
 
 66 
 
 92 
 
 113 
 
 132: 
 
 -145 
 
 
 2 
 
 140 
 
 196 
 
 238 
 
 280 
 
 310 
 
 
 2*A 
 
 240 
 
 328 
 
 400 
 
 470 
 
 515 
 
 
 3 
 
 350 
 
 490 
 
 595 
 
 700 
 
 770 
 
 850 
 
 m 
 
 510 
 
 705 
 
 860 
 
 1010 
 
 1110 
 
 1215 
 
 4 
 
 700 
 
 980 
 
 1190 
 
 1280 
 
 1540 
 
 1660 
 
 A small pipe should never be run to a great height where it 
 only supplies one radiator. It is better to have limits for pipes 
 as follows: 
 
 D in inches: 
 
 Height in feet: 
 
 45 
 
 (Reduce size by 
 floors.) 
 
 TABLE 27. 
 Capacities of Pipes in Square Feet of Direct Steam Radiation. 
 
 
 
 
 
 3 
 
 
 
 i 
 
 
 
 1 
 
 
 
 C3 
 
 ij 
 
 g-^g 
 
 02 
 
 03 
 
 a'*J^ 
 
 a(N 
 
 w 
 
 w' 
 
 ej o a^ 
 
 oj'oB'o 
 
 
 
 03*0 G* 
 
 cj G+J'O 
 
 
 ,0 
 
 O 0$ 5 
 
 5 esS 
 
 CO 
 
 1C 
 
 Q ai5 
 
 Q Ccj H^ 
 
 c* 
 
 it? 
 
 1 
 
 l 
 
 36 
 
 60 
 
 5 
 
 3M, 
 
 3720 
 
 6200 
 
 1^4 
 
 i 
 
 72 
 
 120 
 
 6 
 
 sy% 
 
 6000 
 
 10000 
 
 1% 
 
 1% 
 
 120 
 
 200 
 
 7 
 
 4 
 
 9000 
 
 15000 
 
 2 
 
 i^ 
 
 280 
 
 480 
 
 8 
 
 4 
 
 12800 
 
 21600 
 
 S% 
 
 2 
 
 528 
 
 880 
 
 9 
 
 4% 
 
 17800 
 
 30000 
 
 3 
 
 2% 
 
 900 
 
 1500 
 
 10 
 
 5 
 
 23200 
 
 39000 
 
 3^ 
 
 8% 
 
 1320 
 
 2200 
 
 12 
 
 6 
 
 37000 
 
 62000 
 
 4 
 
 3 
 
 1920 
 
 3200 
 
 14 
 
 7 
 
 54000 
 
 92COO 
 
 *K 
 
 3 
 
 2760 
 
 4600 
 
 16 
 
 8 
 
 76000 
 
 130000 
 
 international Correspondence School. 
 tKent's M. E. Pocket-Book. 
 
 302 
 
TABLE 28. 
 
 Capacities of Hot Water Pipes in Square Feet of Direct 
 Radiation.* 
 
 JHJ 
 
 Q^JS 
 
 Indirect 
 Radial' n 
 
 Direct Radiation. Height of Coil above bottom of boiler, in ft. 
 
 
 
 10 
 
 ' 20 
 
 30 
 
 40 
 
 50 
 
 70 
 
 100 
 
 
 sq. ft. 
 
 sq. ft. 
 
 sq. ft. 
 
 sq. ft. 
 
 sq. ft. 
 
 sq. ft. 
 
 sq. ft. 
 
 3q. ft. 
 
 % 
 
 49 
 
 50 
 
 62 
 
 53 
 
 55 
 
 57 
 
 61 
 
 68 
 
 1 
 
 87 
 
 89 
 
 93 
 
 95 
 
 98 
 
 101 
 
 108 
 
 121 
 
 144 
 
 ]36 
 
 140 
 
 144 
 
 149 
 
 153 
 
 158 
 
 169 
 
 189 
 
 i 1 ^ 
 
 196 
 
 20;: 
 
 209 
 
 214 
 
 222 
 
 228 
 
 243 
 
 271 
 
 2 
 
 349 
 
 359 
 
 370 
 
 380 
 
 393 
 
 405 
 
 433 
 
 483 
 
 tt 
 
 546 
 
 561 
 
 577 
 
 595 
 
 613 
 
 633 
 
 678 
 
 755 
 
 3 
 
 785 
 
 807 
 
 835 
 
 856 
 
 888 
 
 912 
 
 974 
 
 1086 
 
 3% 
 
 1069 
 
 1099 
 
 1133 
 
 1166 
 
 1202 
 
 1241 
 
 1327 
 
 1480 
 
 4 
 
 1395 
 
 1436 
 
 1478 
 
 1520 
 
 1571 
 
 1621 
 
 1733 
 
 1933 
 
 4V 2 
 
 1767 
 
 3817 
 
 1871 
 
 1927 
 
 1988 
 
 2052 
 
 2193 
 
 2445 
 
 5 
 
 3185 
 
 2244 
 
 2309 
 
 2876 
 
 2454 
 
 2531 
 
 2713 
 
 3019 
 
 6 
 
 3140 
 
 3228 
 
 3341 
 
 3424 
 
 3552 
 
 3648 
 
 3897 
 
 4344 
 
 7 
 
 4276 
 
 4396 
 
 4528 
 
 4664 
 
 4808 
 
 4964 
 
 5308 
 
 5920 
 
 8 
 
 5580 
 
 5744 
 
 5912 
 
 6080 
 
 6284 
 
 6484 
 
 6932 
 
 7735 
 
 9 
 
 7068 
 
 7268 
 
 7484 
 
 7708 
 
 7952 
 
 8208 
 
 8774 
 
 9780 
 
 10 
 
 8740 
 
 8976 
 
 9236 
 
 9516 
 
 9816 
 
 10124 
 
 10852 
 
 12076 
 
 11 
 
 10559 
 
 10860 
 
 11180 
 
 11519 
 
 11879 
 
 12262 
 
 13108 
 
 14620 
 
 13 
 
 12560 
 
 12912 
 
 13364 
 
 13696 
 
 14208 
 
 14592 
 
 155S8 
 
 17376 
 
 13 
 
 14748 
 
 15169 
 
 15615 
 
 16090 
 
 16591 
 
 17126 
 
 18307 
 
 20420 
 
 14 
 
 17104 
 
 17584 
 
 18109 
 
 18656 
 
 19232 
 
 19856 
 
 21232 
 
 23680 
 
 15 
 
 19634 
 
 20195 
 
 20789 
 
 31419 
 
 22089 
 
 22801 
 
 24373 
 
 27168 
 
 16 
 
 22320 
 
 22978 
 
 23643 
 
 24320 
 
 25136 
 
 25936 
 
 27728 
 
 30928 
 
 TABLE 
 Capacities of Hot \Vater Mains 
 Radiatioi 
 
 29. 
 iii 
 
 i.t 
 
 Square 
 
 Feet 
 
 of 
 
 Direct 
 
 D. of 
 mains . 
 
 Total 
 
 Estimated 
 
 Length 
 
 of 
 
 Circuit. 
 
 
 100 
 
 200 
 
 300 
 
 400 
 
 500 
 
 600 
 
 700 
 
 800 
 
 900 
 
 1000 
 
 1 
 
 20 
 
 
 
 
 
 
 
 
 
 
 1% 
 
 35 
 
 20 
 
 
 
 
 
 
 
 
 
 1% 
 
 56 
 
 40 
 
 25 
 
 
 
 
 
 
 
 
 2 
 
 116 
 
 85 
 
 70 
 
 50 
 
 
 
 
 
 
 
 VA 
 
 220 
 
 150 
 
 120 
 
 100 
 
 90 
 
 
 
 
 
 
 s 
 
 345 
 
 240 
 
 SCO 
 
 170 
 
 150 
 
 140 
 
 125 
 
 110 
 
 100 
 
 90 
 
 3V 2 
 
 500 
 
 340 
 
 280 
 
 245 
 
 225 
 
 205 
 
 190 
 
 175 
 
 162 
 
 150 
 
 4 
 
 700 
 
 485 
 
 390 
 
 340 
 
 310 
 
 280 
 
 260 
 
 240 
 
 230 
 
 220 
 
 4% 
 
 925 
 
 640 
 
 535 
 
 460 
 
 410 
 
 37f 
 
 345 
 
 325 
 
 300 
 
 295 
 
 5 
 
 1200 
 
 830 
 
 700 
 
 600 
 
 540 
 
 490 
 
 450 
 
 420 
 
 400 
 
 380 
 
 6 
 
 1900 
 
 1325 
 
 1100 
 
 960 
 
 850 
 
 775 
 
 700 
 
 650 
 
 620 
 
 600 
 
 7 
 
 
 2000 
 
 1600 
 
 1400 
 
 1250 
 
 1140 
 
 1050 
 
 975 
 
 925 
 
 875 
 
 8 
 
 
 
 
 1970 
 
 1720 
 
 1550 
 
 1440 
 
 1350 
 
 1300 
 
 1260 
 
 9 
 
 
 
 
 
 
 
 1900 
 
 1800 
 
 1700 
 
 1620 
 
 *Kent's M. E. Pocket-Book. 
 {International Correspondence School. 
 
 303 
 
o 
 
 s w 
 
 1 1 
 
 d <n 
 ^1 
 
 " 
 
 31 
 
 60 O 
 
 fl O 
 
 I 
 
 GO 
 
 M 
 
 8 
 
 S> 
 
 T9A 
 
 doj<i 
 
 zo 
 
 u t pBH 
 'W 'frS 
 
 doaa 
 zo 
 
 u t pi3H 
 
 
 . . 
 
 t- 10 80 <N rH rl rH ' ' 
 
 ; ; 
 
 SO l-H r-5 l-H 
 
 
 
 304 
 
S i-H <N SO * t- 
 
 i-l r-KN <X> * b- 
 
 TtiNC'50l>-COT 
 i-H <M SO "* 10 OS 
 
 t-DDOOOrHr 
 
 Ot-OO-lCtNOOfMOSOSOMCi 
 
 
 I 
 
 
 
 
 
 iSlilllll 
 
 
 JH 
 
 
 
 1 
 
 
 
 1 
 
 
 
 1 
 
 SiSliilil 
 
 
 """* 
 
 
 
 1 
 
 isliliiS 
 
 5<1 . 
 
 
 11 
 
 
 
 8 
 
 ||||||@8 
 
 
 11 
 
 1 IT (1 Ii-Hi I(MS<J*5 
 
 1 
 
 H 
 
 i 
 
 
 fe 
 
 to 
 
 H 
 
 w 
 
 l 
 
 
 LENGT] 
 
 8 
 
 b- 
 
 
 
 i 
 
 
 
 1 
 
 
 
 8 
 
 
 
 i 
 
 
 
 l 
 
 
 
 8 
 
 
 S8T 
 UIM 
 
 IOUI 
 IIHTQ 
 
 ^.O^b.OOOOg,^ 
 
 305 
 
II 
 
 1 1! 
 
 K & 
 
 a fe 
 
 O t. CL 
 
 I 1 
 
 H 5 5; 
 
 J fe ,S 
 
 PQ Uu "^5 
 
 IP 
 
 *J nj fl 
 lw " fe 
 
 1 So 
 
 CO 
 
 CO 
 
 91UUIK 
 
 JO ssoi 
 
 .i9d ^99^ 
 
 91TIUTH 
 
 PT39H 
 
 jed 199.J 
 
 jo ssoi 
 
 .T9d 
 
 ^99.3; UT 
 PB9H JO SSO1 
 
 i^O O O 
 
 1^ ^ <>i 
 
 ^.jx^^- 
 
 i-l IM CO i-l M 
 t- r-( t- 
 
 jgd ^99^; otqno 
 
 UT 
 jo sso r i 
 
 J9d 199^ 
 
 ^99,1 UT 
 PU9H JO SS01 a*^<oo<Ni>:< 
 
 rH <N * <D 00 
 
 KI AXIOO1HA <MM-*iOOb- 
 
 CO 
 
 to 
 
 SSSS3S 
 
 rH<N Tt< 5OQO 
 
 CO b- ^ 
 
 CM 
 
 
 
 ^t- 
 
 3<| < t- i 1 IO O 
 
 oooo 
 
 CO * 10 t 
 
 306 
 
TABLE 33. 
 Expansion Tanks Dimensions and Capacities.* 
 
 Size in Inches 
 
 Capacity Gallons 
 
 Sq. ft. of Radiation 
 
 9x20 
 
 6% 
 
 150 
 
 10x20 
 
 8 
 
 250 
 
 12x20 
 
 10 
 
 350 
 
 12x24 
 
 12 
 
 450 
 
 12x30 
 
 15 
 
 550 
 
 12x36 
 
 18 
 
 650 
 
 14x30 
 
 20 
 
 700 
 
 14x36 
 
 24 
 
 850 
 
 16x30 
 
 26 
 
 900 
 
 16x36 
 
 32 
 
 1250 
 
 16x48 
 
 42 
 
 1750 
 
 18x60 
 
 66 
 
 2750 
 
 20x60 
 
 82 
 
 4500 
 
 22x60 
 
 100 
 
 6000 
 
 24x60 
 
 122 
 
 7500 
 
 TABLE 34. 
 Fr,ee Areas Through Vento Heaters. Regular Adjustments.! 
 
 40-Inch Section 
 
 50-Inch Section 
 
 60-Inch Section 
 
 11.5 sq. ft. per sec. 
 
 14 sq. ft. per sec. 
 
 17 sq. ft. per sec. 
 
 depth of sec. 9 in. 
 
 depth of sec. 9 in. 
 
 depth of sec. 9 in. 
 
 
 cJ . 
 
 
 
 
 
 
 
 
 05 
 
 a) ij 
 
 
 03 
 
 <> +j 
 
 
 03 
 
 s* 
 
 
 3 
 
 ^ 2} 
 
 - r /l 
 
 q 
 
 ^ <1> 
 
 rt fa 
 
 a 
 
 fll 
 
 ~ 03 
 
 o 
 
 8* 
 
 4-> A\ 
 
 S| 
 
 o 
 
 8 . 
 
 "|. 
 
 o 
 
 CJ 
 
 
 
 1 
 
 
 33 
 
 1 
 
 
 
 35 
 
 9 
 
 VI 
 
 faM 
 
 35 
 
 7 
 
 4.34 
 
 35 
 
 7 
 
 5.37 
 
 35 
 
 7 
 
 6.45 
 
 35 
 
 8 
 
 4.96 
 
 40 
 
 8 
 
 6.14 
 
 40 
 
 8 
 
 7.37 
 
 40 
 
 9 
 
 5.58 
 
 45 
 
 9 
 
 6.91 
 
 45 
 
 9 
 
 8.29 
 
 45 
 
 10 
 
 6.20 
 
 50 
 
 10 
 
 7.68 
 
 50 
 
 10 
 
 9.21 
 
 50 
 
 11 
 
 6.82 
 
 55 
 
 11 
 
 8.45 
 
 55 
 
 11 
 
 10.13 
 
 55 
 
 12 
 
 7.44 
 
 60 
 
 12 
 
 9.22 
 
 60 
 
 12 
 
 11.05 
 
 60 
 
 18 
 
 8.06 
 
 65 
 
 13 
 
 9.99 
 
 65 
 
 13 
 
 11.97 
 
 65 
 
 14 
 
 8.68 
 
 70 
 
 14 
 
 10.76 
 
 70 
 
 14 
 
 12.89 
 
 70 
 
 15 
 
 9.30 
 
 75 
 
 15 
 
 11.53 
 
 75 
 
 15 
 
 13.81 
 
 75 
 
 36 
 
 9.92 
 
 80 
 
 16 
 
 12.30 
 
 80 
 
 16 
 
 14.73 
 
 80 
 
 17 
 
 10.54 
 
 85 
 
 17 
 
 13.07 
 
 85 
 
 17 
 
 15.65 
 
 85 
 
 18 
 
 11.16 
 
 90 
 
 18 
 
 13.84 
 
 90 
 
 18 
 
 16.57 
 
 90 
 
 19 
 
 11.78 
 
 95 
 
 19 
 
 14.59 
 
 95 
 
 19 
 
 17.50 
 
 95 
 
 20 
 
 12.40 
 
 100 
 
 20 
 
 15.36 
 
 100 
 
 20 
 
 18.42 
 
 100 
 
 *The Model Boiler Manual, 
 t American Radiator Co. 
 
 Combinations of the 40, 50, and 60 indh sections may be made 
 if large free areas are required or the length of space is limited, 
 thus, a 50, 60 combination of 10 sections gives a free area of 16.89 
 square feet. 
 
 To figure the free area for any job, flivide the total cubic 
 feet of air to be furnished per minute by the velocity per minute, 
 which will give the free area in square feet. 
 
 307 
 
TABLE 35. 
 
 Percentage of Heat Transmitted by Various Pipe-Coverings, 
 
 From Tests Made at Sifoley College, Cornell University, 
 
 and at Michigan University.* 
 
 Relative Amount 
 Kind of Covering-. of Heat 
 
 Transmitted. 
 
 Naked pipe 100. 
 
 Two layers asbestos paper, I in. hair felt, and canvas 
 
 cover 15.2 
 
 Two alyers asbestos paper, 1 in. hair felt, canvas cover, 
 
 wrapped with manilla paper 15 . 
 
 Two layers asbestos paper, 1 in. hair felt 17. 
 
 Hair felt sectional covering, asbestos lined 18.6 
 
 One thickness asbestos board 59.4 
 
 Four thicknesses asbestos paper 50.3 
 
 Two layers asbestos paper 77.7 
 
 Wool felt, asbestos lined 23.1 
 
 Wool felt with air spaces, asbestos lined 19.7 
 
 Wool felt, plaster paris lined 25.9 
 
 Asbestos molded, mixed with plaster paris 31.8 
 
 Asbestos felted, pure long 4 fibre 20.1 
 
 Asbestos and sponge 18.8 
 
 Asbestos and wool felt 20.8 
 
 Magnesia, molded, applied in plastic condition 22.4 
 
 Magnesia, sectional 18.8 
 
 Mineral wool, sectional 19.3 
 
 Rock wool, fibrous 20.3 
 
 Rock wool, felted 20.9 
 
 Fossil meal, molded, % inch thick 29.7 
 
 Pipe painted with black asphaltum 105.5 
 
 Pipe painted with light drab lead paint 108.7 
 
 Glossy white paint 95.0 
 
 'Carpenter's H. ?nd V. B. 
 
 Note. These tests agree remarkably well with a series 
 made by Prof. M. E. Cooley of Michigan University, and also 
 with some made by G. M. Brill, Syracuse, N. Y., and reported 
 in Transactions of the American, Society of Mechanical En- 
 gineers, vol. XVI. 
 
 308 
 
TABLE 36. 
 
 Speeds, Capacities and Horse-Powers of "A B C" Steel 
 Plate Fans at Varying Pressures. 
 
 a] 
 
 Pressures 
 
 
 
 . 
 
 N 
 O 
 
 N 
 
 
 
 s 
 
 8 
 
 N 
 
 H 
 
 O 
 
 * 
 
 Q 
 
 
 
 ^ 
 
 3* 
 
 O 
 
 iH 
 
 1-1 
 
 i 
 
 O 
 
 $ 
 
 CO 
 
 
 CU. FT. 
 
 2740 
 
 3900 
 
 4760 
 
 5490 
 
 6090 
 
 6700 
 
 7350 
 
 7750 
 
 8650 
 
 9520 
 
 30 
 
 R. P. M. 
 
 S80 
 
 540 
 
 659 
 
 760 
 
 847 
 
 930 
 
 1004 
 
 1075 
 
 1200 
 
 1320 
 
 
 H. P. 
 
 0.80 
 
 1.60 
 
 2.66 
 
 3.85 
 
 5.32 
 
 6.65 
 
 8.22 
 
 10.25 
 
 14.38 
 
 18.85 
 
 
 CU. FT. 
 
 3550 
 
 5040 
 
 5490 
 
 7100 
 
 7910 
 
 8700 
 
 9410 
 
 10200 
 
 11210 
 
 1233o 
 
 36 
 
 R. P. M. 
 
 317 
 
 449 
 
 549 
 
 633 
 
 706 
 
 776 
 
 838 
 
 895 
 
 1000 
 
 1100 
 
 
 H. P. 
 
 1.03 
 
 2.05 
 
 3.42 
 
 4.95 
 
 6.84 
 
 8.54 
 
 10.60 
 
 13.2 
 
 18.45 
 
 24.3 
 
 
 CU. FT. 
 
 5220 
 
 7350 
 
 9050 
 
 10400 
 
 11600 
 
 12700 
 
 13750 
 
 14750 
 
 16500 
 
 18000 
 
 42 
 
 R. P. M. 
 
 271 
 
 383 
 
 471 
 
 542 
 
 605 
 
 663 
 
 716 
 
 768 
 
 857 
 
 938 
 
 
 H. P. 
 
 1.51 
 
 3.02 
 
 5.04 
 
 7.30 
 
 10.10 
 
 12.60 
 
 15.60 
 
 19.40 
 
 27.20 
 
 35.7 
 
 
 CU. FT. 
 
 6630 
 
 8900 
 
 10940 
 
 12550 
 
 14000 
 
 15350 
 
 16600 
 
 17800 
 
 19890 
 
 21920 
 
 48 
 
 R. P. M. 
 
 238 
 
 336 
 
 412 
 
 474 
 
 530 
 
 580 
 
 627 
 
 672 
 
 750 
 
 825 
 
 
 H. P. 
 
 1.82 
 
 3.65 1 
 
 6.06 
 
 8.82 
 
 12.15 
 
 15.20 
 
 18.85 
 
 23.40 
 
 32.80 
 
 43.2 
 
 
 CU. FT. 
 
 7850 
 
 11050 
 
 13600 
 
 15600 
 
 17450 
 
 19100 
 
 20650 
 
 22100 
 
 24750 
 
 27300 
 
 54 
 
 R. P. M. 
 
 211 
 
 299 
 
 366 
 
 421 
 
 470 
 
 515 
 
 557 
 
 596 
 
 666 
 
 734 
 
 
 H. P. 
 
 2.27 
 
 4.53 
 
 7.56 
 
 11.00 
 
 15.10 
 
 18,90 
 
 23.40 
 
 29.10 
 
 40.70 
 
 53.5 
 
 
 CU. FT. 
 
 9540 
 
 13500 
 
 16500 
 
 19050 
 
 21300 
 
 23300 
 
 25200 
 
 27000 
 
 30500 
 
 33000 
 
 60 
 
 R. P. M. 
 
 190 
 
 268 
 
 329 
 
 380 
 
 424 
 
 464 
 
 502 
 
 537 
 
 600 
 
 659 
 
 
 H. P. 
 
 2.76 
 
 5.52 
 
 9.20 
 
 13.35 
 
 18.42 
 
 23.00 
 
 28.60 
 
 35.90 
 
 49.60 
 
 65.2 
 
 
 CU. FT. 
 
 11870 
 
 16700 
 
 20600 
 
 23600 
 
 26400 
 
 28900 
 
 31300 
 
 33500 
 
 37500 
 
 41200 
 
 66 
 
 R. P. M. 
 
 173 
 
 2441 300 
 
 345 
 
 385 
 
 422 
 
 456 
 
 488 
 
 546 
 
 600 
 
 
 H. P. 
 
 3.43 
 
 6.85 
 
 11.44 
 
 16.60 
 
 22.90 
 
 28.60 
 
 35.50 
 
 44.00 
 
 61.7 
 
 81.2 
 
 
 CU. FT. 
 
 15000 
 
 21000 
 
 25840 
 
 29700 
 
 33200 
 
 36400 
 
 39400 
 
 42200 
 
 47103 
 
 51800 
 
 72 
 
 R. P. M. 
 
 159 
 
 224 
 
 274 
 
 316 
 
 354 
 
 387 
 
 418 
 
 448 
 
 500 
 
 550 
 
 
 H. P. 
 
 4.32 
 
 8.56 
 
 14.40 
 
 20.90 
 
 28.80 
 
 36.00 
 
 44.60 
 
 55.45 
 
 77.7 
 
 102.1 
 
 
 CU. FT. 
 
 19800 
 
 27900 
 
 34200 
 
 39400 
 
 44000 
 
 48200 
 
 51200 
 
 55800 
 
 63900 
 
 68400 
 
 84 
 
 R. P. M. 
 
 136 
 
 192 
 
 235 
 
 271 
 
 302 
 
 331 
 
 357 
 
 383 
 
 439 
 
 470 
 
 
 H. P. 
 
 5.72 
 
 11.421 
 
 19.00 
 
 27.60 
 
 38.10 
 
 47.60 
 
 59.00 
 
 73.30 
 
 102.7 
 
 135.5 
 
 
 CU. FT. 
 
 25050 
 
 35600 
 
 43700 
 
 50250 
 
 56150 
 
 61500 
 
 66500 
 
 71250 
 
 79200 
 
 87500 
 
 96 
 
 R. P. M. 
 
 118 
 
 168 
 
 206 
 
 237 
 
 265 
 
 290 
 
 314 
 
 336' 
 
 373 
 
 412 
 
 
 H. P. 
 
 7.29 
 
 14.60 
 
 24.32 
 
 35.20 
 
 48.60 
 
 60.75 
 
 75.30 
 
 93.50 
 
 134.0 
 
 172.0 
 
 
 CU. FT. 
 
 31410 
 
 44200 
 
 54300 
 
 62700 
 
 69700 
 
 76700 
 
 82700 
 
 88400 
 
 99000 
 
 108400 
 
 108 
 
 R. P. M. 
 
 109 
 
 149 
 
 183 
 
 211 
 
 235 
 
 259 
 
 279 
 
 298 
 
 334 
 
 366 
 
 
 H. P. 
 
 9.07 
 
 18.13 
 
 30.24 
 
 43.80 
 
 60.48 
 
 75.5 
 
 93.6 
 
 116.20 
 
 131. C 
 
 214.0 
 
 
 CU. FT. 
 
 38000 
 
 53700 
 
 66000 
 
 75700 
 
 84950 
 
 93000 
 
 100500 
 
 107200 
 
 12CX/X) 
 
 134000 
 
 120 
 
 R. P. M. 
 
 95 
 
 134 
 
 165 
 
 189 
 
 212 
 
 232 
 
 251 
 
 268 
 
 300 
 
 330 
 
 
 PI. P. 
 
 11.02 
 
 22.20 
 
 36.80 
 
 53.3 
 
 73.5 
 
 92.0 
 
 114.0 
 
 141.5 
 
 198.5 
 
 261.0 
 
 
 CU. FT. 
 
 46800 
 
 66300 
 
 80900 
 
 93200 
 
 104000 
 
 113500 
 
 123300 
 
 131400 
 
 ^47100 
 
 161500 
 
 132 
 
 R. P. M. 
 
 87 
 
 123 
 
 150 
 
 173 
 
 193 
 
 211 
 
 229 
 
 244 
 
 274 
 
 300 
 
 
 H. P. 
 
 13.48 
 
 27.00 
 
 44.90 
 
 65.10 
 
 89.6 
 
 112.0 
 
 1J9.0 
 
 173.0 
 
 243.0 
 
 318.0 
 
 
 CU. FT. 
 
 56400 
 
 79000 
 
 96500 
 
 12000 
 
 124800 
 
 136800 
 
 147400 
 
 158000 
 
 176100 
 
 194000 
 
 144 
 
 R. P. M. 
 
 80 
 
 112 
 
 137 
 
 159 
 
 177 
 
 194 
 
 209 
 
 224 
 
 250 
 
 275 
 
 
 H. P. 
 
 16.10 
 
 32.30 
 
 53.80 
 
 78.00 
 
 107.4 
 
 134.0 
 
 166.0 
 
 206.0 
 
 290.0 
 
 382.0 
 
 
 The capacities are based on the average results obtained when 
 applied to the heating of buildings, and are reliable for such in- 
 stallations. Three Quarter ounce pressure is common practice. 
 
 309 
 
TABLE 37. 
 
 Speeds, Capacities and Horse-Powers of "Green" Steel Plate 
 Fans at Varying Pressures. 
 
 i| 
 
 Pressures 
 
 
 
 8 
 
 
 
 tsj 
 o 
 
 8 
 
 af 
 
 8 
 
 N 
 O 
 
 g 
 
 N 
 O 
 
 44 
 
 o 
 
 
 CU. FT. 
 
 2249 
 
 3176 
 
 3891 
 
 4498 
 
 5029 
 
 5513 
 
 5956 
 
 6372 
 
 7135 
 
 30 
 
 R. P. M. 
 
 330 
 
 466- 
 
 571 
 
 660 
 
 738 
 
 809 
 
 874 
 
 985 
 
 1047 
 
 
 H. P. 
 
 .286 
 
 .811 
 
 1.491 
 
 2.298 
 
 3.213 
 
 4.227 
 
 5.311 
 
 6.515 
 
 9.120 
 
 
 CU. FT. 
 
 3239 
 
 4581 
 
 5605 
 
 6477 
 
 7242 
 
 7937 
 
 8584 
 
 9173 
 
 10268 
 
 36 
 
 R. P. M. 
 
 275 
 
 389 
 
 476 
 
 550 
 
 615 
 
 674 
 
 729 
 
 779 
 
 872 
 
 
 H. P. 
 
 .413 
 
 1.170 
 
 2.148 
 
 3.311 
 
 4.625 
 
 6.080 
 
 7.681 
 
 9.376 
 
 13.125 
 
 
 CU. FT. 
 
 4398 
 
 6214 
 
 7617 
 
 8815 
 
 9864 
 
 10799 
 
 11679 
 
 12483 
 
 13981 
 
 42 
 
 R. P. M. 
 
 235 
 
 332 
 
 407 
 
 471 
 
 527 
 
 577 
 
 624 
 
 667 
 
 747 
 
 
 H. P. 
 
 .557 
 
 1.576 
 
 2.898 
 
 5.473 
 
 6.300 
 
 8.287 
 
 10.4501 
 
 12.750 
 
 
 
 CU. FT. 
 
 5750 
 
 8123 
 
 9937 
 
 11500 
 
 12867 
 
 14123 
 
 15240 
 
 16301 
 
 18282 
 
 48 
 
 R. P. M. 
 
 206 
 
 291 
 
 356 
 
 412 
 
 461 
 
 506 
 
 546 
 
 584 
 
 655 
 
 
 H. P. 
 
 .733 
 
 2.076 
 
 3.810 
 
 5.880 
 
 8.223 
 
 10.832 
 
 13.636 
 
 16.670 
 
 23.370 
 
 
 CU. FT. 
 
 7602 
 
 10758 
 
 13167 
 
 15203 
 
 17030 
 
 18650 
 
 20145 
 
 21558 
 
 24174 
 
 54 
 
 R. P, M. 
 
 183 
 
 259 
 
 sir 
 
 366 
 
 410 
 
 449 
 
 485 
 
 519 
 
 5S2 
 
 
 H. P. 
 
 .970 
 
 2.750 
 
 5.047 
 
 7.767 
 
 10.880 
 
 14.300 
 
 18.017 
 
 21.992= 
 
 30.896 
 
 
 CU. FT. 
 
 9715 
 
 13718 
 
 16780 
 
 19429 
 
 21725 
 
 23786 
 
 25728 
 
 27495 
 
 307'92 
 
 60 
 
 R. P. M. 
 
 165 
 
 233 
 
 285 
 
 330 
 
 369 
 
 404 
 
 437 
 
 467 
 
 523 
 
 
 H. P. 
 
 1.241 
 
 3.506 
 
 6.433 
 
 9.932 
 
 13.882 
 
 18.230 
 
 22.996 
 
 28.077 
 
 39.355 
 
 
 CD. FT. 
 
 12078 
 
 17071 
 
 20855 
 
 24156 
 
 26975 
 
 29551 
 
 32047 
 
 34221 
 
 38247 
 
 66 
 
 R. P. M. 
 
 150 
 
 212 
 
 259 
 
 300 
 
 335 
 
 367 
 
 398 
 
 425 
 
 475 
 
 
 H. P. 
 
 1.542 
 
 4.361 
 
 7.996 
 
 12.352 
 
 17.238 
 
 22.666 
 
 28.675 
 
 35.123 
 
 48.895 
 
 
 CU. FT. 
 
 15608 
 
 21942 
 
 26918 
 
 31103 
 
 34835 
 
 38115 
 
 41169 
 
 44109 
 
 49312 
 
 72 
 
 R. P. M. 
 
 138 
 
 194 
 
 238 
 
 275 
 
 308 
 
 337 
 
 364 
 
 390 
 
 436 
 
 
 H. P. 
 
 1.983 
 
 5.601 
 
 10.322 
 
 15.881 
 
 22.252! 
 
 29.223 
 
 36.808 
 
 45.043 
 
 62.783 
 
 
 CU. FT. 
 
 20192 
 
 28405 
 
 34907 
 
 40383 
 
 45174 
 
 49452 
 
 53387 
 
 57152 
 
 63996 
 
 84 
 
 R. P. M. 
 
 118 
 
 166 
 
 204 
 
 236 
 
 264 
 
 289 
 
 312 
 
 334 
 
 374 
 
 
 H. P. 
 
 2.581 
 
 7.262 
 
 13.387 
 
 20.650 
 
 28.875 
 
 37.931 
 
 47.775 
 
 58.450 
 
 81.812 
 
 
 CU. FT. 
 
 23008 
 
 32614 
 
 39762: 
 
 46016 
 
 51601 
 
 56515 
 
 60983 
 
 65227 
 
 73045 
 
 96 
 
 R. P. M. 
 
 103 
 
 146 
 
 178 
 
 206 
 
 231 
 
 253 
 
 273 
 
 292 
 
 327 
 
 
 H. P. 
 
 2.941 
 
 8.337 
 
 15.261 
 
 23.531 
 
 32.982 
 
 43.348 
 
 54.511 
 
 66.707 
 
 93.380 
 
 
 CU. FT. 
 
 29260 
 
 41027 
 
 50568 
 
 58519 
 
 65198 
 
 71559 
 
 77284 
 
 82690 
 
 92549 
 
 108 
 
 R. P. M. 
 
 92 
 
 129 
 
 159 
 
 184 
 
 205 
 
 225 
 
 243 
 
 260 
 
 291 
 
 
 H. P. 
 
 3.737 
 
 10.488 
 
 19.397 
 
 30.060 
 
 41.666 
 
 54.871 
 
 69.163 
 
 84.556 
 
 118.291 
 
 
 CU. FT. 
 
 36209 
 
 51043 
 
 62384 
 
 71982 
 
 80270 
 
 88559 
 
 95539 
 
 102083 
 
 114298 
 
 120 
 
 R. P. M. 
 
 83 
 
 117 
 
 143 
 
 165 
 
 184 
 
 203 
 
 219 
 
 234 
 
 262 
 
 
 H. P. 
 
 4.628 
 
 13.050 
 
 23.925 
 
 36.807 
 
 51.307 
 
 67.928 
 
 85.495 
 
 104.401 
 
 146.116 
 
 
 CU. FT. 
 
 43560 
 
 61565 
 
 75504 
 
 87120 
 
 97575 
 
 106868 
 
 115580 
 
 123711 
 
 138231 
 
 132 
 
 R. P. M. 
 
 75 
 
 106 
 
 130 
 
 150 
 
 168 
 
 184 
 
 1991 
 
 213 
 
 238 
 
 
 H. P. 
 
 5.568 
 
 15.730 
 
 28.957 
 
 44.550 
 
 62.370 
 
 82.096 
 
 103.430 
 
 126.521 
 
 176.715 
 
 
 CU. FT. 
 
 52026 
 
 73138 
 
 89726 
 
 103298 
 
 116116 
 
 127426 
 
 137228 
 
 147030 
 
 164378 
 
 144 
 
 R. P. M. 
 
 69 
 
 97 
 
 119 
 
 137 
 
 154 
 
 169 
 
 182 
 
 195 
 
 218 
 
 
 H. P. 
 
 6.69 
 
 18.700 
 
 34.411 
 
 52.822 
 
 74.221 
 
 97.741 
 
 122.802 
 
 150.371 
 
 210.133 
 
 Note The hosre-power required to drive a fan will vary ac- 
 cording to the manner of application. The horse-powers given 
 above are 25 per cent, greater than would be required under ideal 
 conditions. 
 
 310 
 
TABLE 38. 
 
 Speeds, Capacities and Horse-Powers of Sirocco Type Fans 
 with No. 1 Blades, at Varying Pressures. 
 
 Figures given represent dynamic pressures in ozs. per 
 square inch. For static pressure deduct 28.8%. For velocity 
 pressure deduct 71.2%. 
 
 IDiam. 
 [Wheel 
 
 Pressures 
 
 8 
 g 
 
 8 
 
 ^? 
 
 8 
 s* 
 
 g 
 
 T-H 
 
 | 
 
 3* 
 
 H 
 
 6 
 
 ^ 
 
 N 
 
 O 
 
 ^ 
 
 N 
 
 O 
 
 c* 
 
 M 
 
 O 
 
 i 
 
 H 
 
 Q 
 
 n 
 
 
 CU. FT. 
 
 155 
 
 220 
 
 2TO 
 
 310 
 
 350 
 
 380 
 
 410 
 
 440 
 
 490 
 
 540 
 
 6 
 
 R. P. M. 
 
 1145 
 
 1615 
 
 1980 
 
 2280 
 
 2560 
 
 2800 
 
 3005 
 
 3230 
 
 3616 
 
 3960 
 
 
 B. H. P. 
 
 .0185' 
 
 .052 
 
 .095 
 
 .147 
 
 .205 
 
 .270 
 
 .34 
 
 .42 
 
 .58 
 
 .76 
 
 
 CU. FT. 
 
 350 
 
 500 
 
 610 
 
 700 
 
 790 
 
 860 
 
 930 
 
 1000 
 
 1110 
 
 1220 
 
 9 
 
 R. P. M. 
 
 762 
 
 1076 
 
 1320 
 
 1524 
 
 1700 
 
 1866 
 
 2020 
 
 31521 
 
 2408 
 
 2040 
 
 
 B. H. P. 
 
 .042 
 
 .118 
 
 .216 
 
 .333 
 
 .463- 
 
 .610 
 
 .77 
 
 .95 
 
 1.3* 
 
 1.73 
 
 
 CU. FT. 
 
 625 
 
 880 
 
 1080 
 
 1250 
 
 1400 
 
 1530 
 
 1650 
 
 1770 
 
 1970 
 
 2170 
 
 12 
 
 R. P. M. 
 
 572 
 
 808 
 
 990 
 
 1145 
 
 1280 
 
 1400 
 
 1512 
 
 1615 
 
 1808 
 
 1980 
 
 
 B. H. P. 
 
 .074 
 
 .208 
 
 .381 
 
 .588 
 
 .80 
 
 1.08 
 
 1.36 
 
 1.60 2.32 
 
 3.05 
 
 
 CU. FT. 
 
 975 
 
 1380 
 
 1690 
 
 1950 
 
 2180 
 
 2400 
 
 2590 
 
 2760 3090 
 
 3390 
 
 15 
 
 R. P. M. 
 
 456 
 
 645 
 
 790 
 
 912 
 
 1020 
 
 1120 
 
 1210 
 
 1290, 1444 
 
 1580 
 
 
 B. H. P. 
 
 .115 
 
 .326 
 
 .600 
 
 .923 
 
 1.29 
 
 1.69 
 
 2.14 
 
 2.61 3.65 
 
 4.8 
 
 
 CU. FT. 
 
 1410 
 
 1990 
 
 2440 
 
 2820 
 
 3160 
 
 3450 
 
 3720 
 
 3980 4450 
 
 4830 
 
 18 
 
 R. P. M. 
 
 381 
 
 538 
 
 660 
 
 762 
 
 850 
 
 933 
 
 1010 
 
 1076| 1204 
 
 1320 
 
 
 B. H. P. 
 
 .167 
 
 .470 
 
 .862 
 
 1.33 
 
 1.85 
 
 2.43 
 
 3.07 
 
 3.75 
 
 5.25 
 
 6.9 
 
 
 CU. FT. 
 
 1925 
 
 2710 
 
 3310 
 
 3850 
 
 4290 
 
 4700 
 
 5070 
 
 5420 
 
 6060 
 
 6620 
 
 21 
 
 R. P. M. 
 
 326 
 
 463 
 
 565 
 
 652 
 
 730 
 
 800 
 
 864 
 
 924 
 
 1032 
 
 1130 
 
 
 B. H. P. 
 
 .227 
 
 640 
 
 1.17 
 
 1.81 
 
 2.53 
 
 3.33 
 
 4.18 
 
 5.11 
 
 7.15 
 
 9. A 
 
 
 CU . FT . 
 
 2500 
 
 3540 
 
 4340 
 
 5000 
 
 5600 
 
 6120 
 
 6620 
 
 7080 
 
 7900 
 
 8680 
 
 24 
 
 R. P. M. 286 
 
 404 
 
 495 
 
 572 
 
 640 
 
 700 
 
 756 
 
 807 
 
 904 
 
 990 
 
 
 B. H. P. 
 
 .296 
 
 .832 
 
 1.53 
 
 2.35 
 
 3.28 
 
 4.32 
 
 5.44' 
 
 6.64 
 
 9.3 
 
 ]2.2 
 
 
 CU. FT. 
 
 3175 
 
 4490 
 
 5500 
 
 6350 
 
 7100 
 
 7780 
 
 8400 
 
 8980 
 
 10050 
 
 11000 
 
 27 
 
 R. P. M. 
 
 254 
 
 359 
 
 440 
 
 508 
 
 568 
 
 622 
 
 673 
 
 718 
 
 804 
 
 88Q 
 
 
 B. H. P. 
 
 .373 
 
 1.05 
 
 1.94 
 
 2.98 
 
 4.16 
 
 5.48 
 
 6.90 
 
 8.44 
 
 11.8 
 
 15.fi 
 
 
 CU. FT. 
 
 3910 
 
 5520 
 
 6770 
 
 7820 
 
 8750 
 
 9600 
 
 10350 
 
 11050 
 
 12330 
 
 13550 
 
 30 
 
 R. P. M. 
 
 228 
 
 322 
 
 395 
 
 456 
 
 510 
 
 560" 
 
 604 
 
 645 
 
 723 
 
 790 
 
 
 B. H. P. 
 
 .460 
 
 1.30 
 
 2.40 
 
 3.68 
 
 5.15 
 
 6.75 
 
 8.53 
 
 10.4 
 
 14.5 
 
 19.1 
 
 
 CU FT. 
 
 5650 
 
 7950 
 
 9750 
 
 11300 
 
 12640 
 
 13800 
 
 14900 
 
 15900 
 
 178CO 
 
 19500 
 
 36 
 
 R. P. M. 
 
 190 
 
 269 
 
 330 
 
 381 
 
 425 
 
 466 
 
 504, 
 
 538 
 
 602 
 
 660 
 
 
 B. H. P. 
 
 .665 
 
 1.87 
 
 3.44 
 
 5.30 
 
 7.40 
 
 9.72 
 
 12.29 
 
 15.0 
 
 20.9 
 
 27.5 
 
 
 CU . FT . 
 
 770 
 
 10850 
 
 13300 
 
 15400 
 
 17170 
 
 18800 
 
 20300 
 
 21700 
 
 24250 
 
 26600 
 
 42 
 
 R. P. M. 
 
 163 
 
 231 
 
 283 
 
 326 
 
 365 
 
 400 
 
 432 
 
 463 
 
 516 
 
 566 
 
 
 B. H. P. 
 
 .903 
 
 2.55 
 
 4.69 
 
 7.24 
 
 10.1 
 
 13.3 
 
 16.7 
 
 20.4 
 
 28.5 
 
 87.5 
 
 311 
 
II 
 
 Q 
 
 Pressures 
 
 
 
 
 
 i 
 
 o 
 
 M 
 
 N 
 
 O 
 
 S* 
 
 N 
 
 O 
 
 N 
 O 
 
 g 
 
 o 
 
 N 
 O 
 
 ot 
 
 5 
 
 
 CU. FT. 
 
 10000 
 
 14150 
 
 17350 
 
 20000 
 
 22400 
 
 24500 
 
 26500 
 
 28300 
 
 31600 
 
 34700 
 
 48 
 
 R. P. M. 
 
 143 
 
 202 
 
 248 
 
 286 
 
 320 
 
 350 
 
 378 
 
 403 
 
 452 
 
 495 
 
 
 B. H. P. 
 
 1.18 
 
 3.32 
 
 6.10 
 
 9.40 
 
 13.1 
 
 17.2 
 
 21.75 
 
 26.0 
 
 37.1 
 
 48.8 
 
 
 CU. FT. 
 
 12700 
 
 17950 
 
 22000 
 
 25400 
 
 28400 
 
 31100 
 
 33600 
 
 35900 
 
 40200 
 
 44000 
 
 54 
 
 R. P. M. 
 
 127 
 
 179 
 
 220 
 
 254 
 
 284 
 
 311 
 
 336 
 
 359 
 
 4025 
 
 440 
 
 
 B. H. P. 
 
 1.49 
 
 4.20 
 
 7.75 
 
 11.9 
 
 16.6 
 
 21.9 
 
 27.6 
 
 ,33.7 
 
 47.1 
 
 62 
 
 
 CU. FT. 
 
 15650 
 
 22100 
 
 27100 
 
 31300 
 
 35000 
 
 38400 
 
 41400 
 
 44200 
 
 49400 
 
 54200 
 
 60 
 
 R. P. M. 
 
 114 
 
 161 
 
 198 
 
 228 
 
 255 
 
 280 
 
 302 
 
 322 
 
 sen. 
 
 396 
 
 
 B. H. P 
 
 1.84 
 
 5.20 
 
 9.58 
 
 14.7 
 
 20.6 
 
 27.0 
 
 34.1 
 
 41.6 
 
 58.2 
 
 76.5 
 
 
 CU. FT. 
 
 18950 
 
 26800 
 
 32850 
 
 37900 
 
 42300 
 
 46400 
 
 50100 
 
 53600 
 
 60000 
 
 65700 
 
 66 
 
 R. P. M. 
 
 104 
 
 147 
 
 180 
 
 208 
 
 232 
 
 254 
 
 275 
 
 294 
 
 328' 
 
 360 
 
 
 B. H. P. 
 
 2.23 
 
 6.30 
 
 11.6 
 
 17.8 
 
 24.9 
 
 32.7 
 
 41.2 
 
 50.4 
 
 70.4 
 
 92.6 
 
 
 CU. FT. 
 
 22600 
 
 31800 
 
 39000 
 
 45200 
 
 50600 
 
 55200 
 
 59600 
 
 63600 
 
 71200 
 
 78000 
 
 72 
 
 R. P. M. 
 
 95 
 
 134 
 
 165 
 
 190 
 
 212 
 
 233 
 
 253 
 
 269 
 
 301 
 
 330 
 
 
 B. H. P. 
 
 2.66 
 
 7.48 
 
 13.7 
 
 21.2 
 
 29.6 
 
 38.9 
 
 49.0 
 
 59.8 
 
 83.6 
 
 no 
 
 
 CU. FT. 
 
 26400 
 
 37350 
 
 15800 
 
 52800 
 
 59100 
 
 64700 
 
 70000 
 
 74700 
 
 83500 
 
 91600 
 
 78 
 
 R. P. M. 
 
 88 
 
 124 
 
 15S 
 
 176 
 
 197 
 
 215 
 
 233 1 
 
 248 
 
 278 
 
 305 
 
 
 B. H. P. 
 
 3.10 
 
 8.77 
 
 16.1 
 
 24.8 
 
 34.7 
 
 45.6 
 
 57.5 
 
 70.2 
 
 98 
 
 129 
 
 
 CU. FT. 
 
 40800 
 
 i3400 
 
 1.3200 
 
 61600 
 
 38700 
 
 75200 
 
 812CO 
 
 86800 
 
 97100 
 
 L06400 
 
 84! 
 
 R. P. M. 
 
 81 
 
 115 
 
 142 
 
 163 
 
 182 
 
 200 
 
 216 
 
 231 
 
 258 
 
 283 
 
 
 B. H. P. 
 
 3.61 
 
 10.2 
 
 18.7 
 
 28.9 
 
 40.4 
 
 63.0 
 
 66.8 
 
 81.7 
 
 114 
 
 150 
 
 
 CU. FT. 
 
 4 52St 
 
 i9800 
 
 61000 
 
 70500 
 
 /8800 
 
 86400 
 
 93300 
 
 99600 
 
 111200 
 
 122000 
 
 90 
 
 R. P. M. 
 
 7t 
 
 107 
 
 133 
 
 152 
 
 170 
 
 186 
 
 201 
 
 214 
 
 241 
 
 264 
 
 
 B. H. P. 
 
 4.14 
 
 11.7 
 
 21.5 
 
 33.1 
 
 46.2 
 
 60.7 
 
 76.7 
 
 93.6 
 
 131 
 
 172 
 
 312 
 
TABLE 39. 
 Dimensions of Ells and Tees for Wrought Iron Pipe. 
 
 SIZE 
 
 E 
 
 1- 
 
 4- 
 
 4- 1 /, 
 
 5- 
 
 6- 
 
 6-34 
 
 l-t's 
 
 TT/ 
 
 1- 
 
 l-jl 
 
 4- 
 
 2-J4 
 
 2-% 
 S-% 
 4- 
 
 6- 
 
 6-% 
 
 i- 
 i- 
 
 i-y s 
 
 2- 
 2-% 
 
 4- 
 
 4-% 
 
 Diagrams for Pipe Sizes and Friction Heads. 
 
 To illustrate the use of the two following diagrams, ap- 
 ply to the pipe line B, C, Art. 144. First, let I = 1500 feet, 
 d = 8 inches and v = 5 feet per second. Trace along the 
 velocity line until it intersects the diameter line, then fol- 
 low the ordinate to the top of the page and find the friction 
 head, 13 feet for 1000 foot run or 19.5 feet for the 1500 foot 
 run. Second, let Q = 1.75 cubic feet per second and d = 8 
 inches. Trace to the left along the horizontal line represent- 
 ing the volume of 1.75 cubic feet until it intersects the 
 diameter line, then read up and find the same friction head 
 as before. Third, let the allowable iriction head for 1500 
 feet of main be 19 feet, when Q = 1.75 cubic feet per second 
 or when v = 5 feet per second. Reverse the process given 
 above and find an 8 inch pipe. 
 
 313 
 
as: ex- J-.: 
 
 5 rv 
 
 O 
 
 5-3* 
 
 - .= = o v ; \x ". u 
 
 i*S^3s:id^ \ ,- 
 5i>:rs o Ltv % ' .> 
 
 314 
 
315 
 
INDEX 
 
 Absolute pressure, 11 
 
 temperature, 10 
 
 Advantages of vac. systems, 169 
 Air, amount to burn carbon, 32 
 circulation, furnace system, 47 
 circulation within room, 69 
 composition, 14 
 exhausted from nozzle. 152 
 horse power in moving, 154 
 humidity of, 23 
 leakage, heat loss by, 37 
 needed, plenum system, 136 
 per person, table of, 21 
 required as heat carrier, 48 
 temperatures, plenum system, 142 
 valves, 91 
 
 velocity, plenum system, 136, 148 
 ventilating, per person, 19 
 washing and humidifying, 131 
 Anchors, types of, 192 
 Anemometer, 29 
 Appendix 
 
 table 1 squares, cubes, etc., 271 
 table 2 properties of steam, 278 
 table 3 Naperian logarithms, 285 
 table 4 water conversion fac- 
 tors, 285 
 table 5 volume and weight of 
 
 dry air, 286 
 
 table 6 weight of pure water, 287 
 table 7 boiling points of water, 
 
 289 
 table 8 weight of water in air, 
 
 289 
 
 table 9 properties of air, 290 
 table 10 relative humidities, 291 
 table 11 fuel values Am. coal, 292 
 table 12 cap. of chimneys, 293 
 table 13 equalization of smoke 
 
 flues, 294 
 
 table 14- diam. of registers, 294 
 table 15 specific heat, etc., of sub- 
 stances, 295 
 tables 16, 18 capacities of furnaces, 
 
 296, 297 
 table 17 capacities of pipes and 
 
 registers, 296 
 
 table 19 area vertical flues, 297 
 tables 20, 21 water pressures, 298 
 table 22 wrought iron pipes, 299 
 table 23 expansion of pipes, 300 
 table 24 tapping list of rad., 300 
 table 25 pipe equalization, 301 
 table 26 cap. hot water risers, 302 
 table 27 cap. steam pipes, 302 
 table 28 cap. hot water pipes, 303 
 table 29 cap. hot water mains, 303 
 
 tables 30, 31 sizes of steam mains, 
 
 304, 305 
 table 32 loss of head by friction 
 
 of pipes, 306 
 
 table 33 expansion tanks, 307 
 table 34 sizes of Vento heaters, 307 
 table 35 heat trans, through pipe 
 
 coverings, 308 
 
 tables 36, 37, 38 speeds, cap. h. p. 
 of various fans, 309-312 
 table 39 dim. ells and tees, 313 
 Application of plenum system, 162 
 Area of ducts, plenum system, 136 
 Arrangement of Vento heaters, 145 
 
 of coils, plenum system, 144 
 Automatic vacuum sys., piping, 177 
 Automatic valves, 177 
 
 Basement plans, plenum sys., 165 
 
 Belvac thermofiers, 175 
 
 Blowers and fans, 119 
 speeds of, table, 158 
 work, Carpenter's rules, 155 
 
 Boilers, 223 
 feed pumps, 221 
 capacity and number of, 227 
 radiation supplied by, 224 
 
 Boiling point of water, table, 289 
 
 British thermal unit, 8 
 lost in plenum system, 140 
 
 Building material conductivities, 36 
 
 Calculating chimney area, 32 
 Calculating heat losses, 35 
 Calorie, 8 
 
 Carbon, amount of air to burn, 32 
 Carbon dioxide, per cent, table, 19 
 Carbon dioxide, tests for, 16 
 Carpenter's practical rules, 155 
 Cast radiators, 82, 84 
 Cast surfaces, plenum systems, 126 
 Centrifugal pumps, 219 
 Chart, hygrometric, 26 
 Chimneys, 33 
 
 capacity of, table, 293 
 Circulating duct in furnace design, 
 
 65 
 
 Circulating pumps, 216 
 Circulating water to condense 
 
 steam, 209 
 
 Classification of radiators, 82 
 Coal, fuel values of. table, 292 
 Coil surface, plenum system, 124, 
 
 125, 129, 141 
 Combination heaters, 63 
 
 system, 87 
 Condensation, dripping from mains, 
 
318 
 
 INDEX 
 
 return to boilers, 110 
 Condenser for exhaust steam, 210 
 
 heating surface in, 211 
 Conduction, 12 
 
 Conductivities of building materi- 
 als, 86 
 
 Conduits, central station htg., 185 
 Convection, 13 
 
 Conversion factors for water, 285 
 Data table for plenum systems, 164 
 Design, hot water and steam, 93 
 
 reports, instructions for 1, 2, 3, 
 258 
 
 reports, instructions for 4, 259 
 
 reports, instructions for 5, 261 
 
 Determination of pipe sizes, 99 
 Direct radiation, tapping list, table, 
 
 300 
 
 Dirt strainer, Webster, 173 
 District heating, 181 
 
 adaptation to private plants, 239 
 
 amount of radiation supplied, 208 
 
 amount supplied by reheater, 213 
 
 application to typical design, 239 
 
 boiler feed pumps, 221 
 
 by steam, 236 
 
 condensation from mains, 239 
 
 conduits, 185 
 
 cost of heating, 230 
 
 cost, summary of tests 232 
 
 diameter of mains, 205 
 
 economizers, 225 
 
 exhaust steam used in, 194, 210 
 
 future increase, 202 
 
 heating surface in reheater, 211, 
 213 
 
 high pressure steam heater, 216 
 
 important reheater details, 214 
 
 layout for conduit mains, 188 
 
 power plant layout, 231 
 
 pressure drop in mains, 203, 205, 
 237 
 
 radiation in district. 202 
 
 radiation supplied by 1 h. p. of 
 ex. St., 209 
 
 regulation, 235 
 
 scope of work, 183 
 
 service connections, 207 
 
 steam available for heating, 207 
 
 systems classified, 182, 200 
 
 typical design, 193 
 
 velocity of water in mains, 205 
 Division of coils, plenum sys., 129 
 Ducts, furnace, cold air, 53 
 
 plenum system, 129, 130 
 
 recirculating, 65 
 
 Economizers, 225 
 
 radiation supplied by, 225 
 
 surface, 226, 227 
 
 Efficiency of plenum coils, table, 139 
 Electrical heating, 253 
 
 formulas used in, 253 
 
 Exhaust stepm available in district 
 
 plants, 194-199 
 
 Exhaust steam condenser, 210 
 Expansion joints, 190 
 
 tanks, 92 
 Exposure heat losses, table, 38 
 
 Factor table, velocity and vol., 152 
 Fans and blowers.. 70, 119 
 
 drives, 157 
 
 housings, 121 
 
 power of engine for, 159 
 Fire places, stoves, etc., 117 
 Fittings, steam and hot water, 89 
 Floor plans for furnace heating, 
 
 106-108 
 
 Floor plans for plenum sys., 165-167 
 Formulas, empirical for radiation, 96 
 Fresh air duct, 53-64 
 Fresh air entrance to bldgs., 123 
 Fuel values of Am. coals, table, 292 
 Furnace, 
 
 air circulation within room, 69 
 
 foundations, 64 
 
 heating, 45 
 
 location, 64 
 
 selection, 60 
 Furnace system, air circulation, 47 
 
 air required as heat carrier, 47 
 
 circulating duct in, 65 
 
 design of, 55 
 
 essentials of, 46 
 
 fan in, 70 
 
 fresh air duct in, 53, 64 
 
 grate area in, 63 
 
 gross register area in, 51 
 
 heat stacks, sizes of, 51, 67 
 
 heating surface in, 54 
 
 leader pipes in, 52, 66 
 
 net vent register in, 51 
 
 plans for, 57 
 
 points to be calculated in, 47 
 
 registers, temperatures in, 50 
 
 stacks or risers in, 67 
 
 three methods of installation, 49 
 
 vent stacks, 69 
 
 Gage pressures, 11 
 
 Grate area, boilers and heaters, 101 
 Grate area for furnaces, 53 
 Greenhouse heating, 97 
 
 Hammer, water, 110 
 Heat given off by persons, lights, 
 etc., 43 
 
 latent, 11 
 
 measurement of, 8 
 
 mechanical equivalent of, 11 
 
 stacks, sizes of, 51, 67 
 Heaters, hot water, 87 
 Heating, district, cost of, 230 
 Heating surface in coils, plenum sys- 
 tem, 137 
 
INDEX 
 
 319 
 
 Heating sur., in economizer, 226, 227 
 
 in furnace system, 54 
 
 in reheater, 211 
 
 per h. p. in reheater, 213 
 Heat loss, 37, 38, 39, 41, 134 
 
 calculation of, 35 
 
 combined, 41 
 
 for a 10 room house, table, 56 
 High pressure heater, 216 
 High pressure steam trap, 110 
 Horse power, in moving air, 154, 155 
 
 of engine for fan, 159 
 
 required to move air in plenum 
 
 system, 150 
 Hot air pipes, cap. of, table, 296 
 
 water heaters, 87 
 
 water pipes, capacity of, table, 302 
 
 water radiators, 85 
 
 water risers, cap. of, table, 303 
 
 water system, 72 
 
 water used in indirect coils in ple- 
 num, system, 146 
 Hot water and steam heating, 
 
 calculations for rad. sur. for, 93 
 
 classifications, 75 
 
 determination of pipe sizes for, 99 
 
 empirical formula for, 96 
 
 grate area for heater, 101 
 
 greenhouse radiation, 97 
 
 location of radiators for, 102 
 
 parts of, 73 
 
 pitch of mains for, 102 
 
 principles of design of, 93 
 
 second classification of, 76 
 
 typical layout of, 103 
 Humidity of the air, 23 
 Humidities, relative, table, 291 
 Hygrodeik, 24 
 Hygrometer, 23 
 Hygrometric chart, 26 
 
 Indirect radiators, 76 
 Installation of steam pipes, 109 
 Instructions for design reports, Nos. 
 
 1, 2, 3, 258 
 
 for design report, No. 4, 259 
 for design report, No. 5, 261 
 'K,' values for pipe coils, table, 139 
 'K,' values for Vcnto coils, table, 
 
 141 
 
 outline of course in, 257 
 suggestions for course in, 256 
 
 Latent heat, 11 
 
 Layout for furnace system, 106 
 
 for hot water heating plant, 103 
 
 for plenum system, 127, 128 
 
 of power plant, 231 
 
 steam mains and conduits, 188 
 Leader pipes, 52, 66 
 Location of furnaces, 64 
 
 of radiators, 102 
 Low pressure steam traps, 110 
 
 Mains, condensation, dripping from, 
 239 
 
 cap. of hot water, table, 303 
 
 diameter of, 205 
 
 pitch of, 102 
 
 pressure drop and diameter of, 237 
 
 velocity of water in, 205 
 Manholes, 193 
 Measurement o,f air velocities, 29 
 
 of heat, 8 
 
 of high temperatures, 9 
 Mechanical vacuum steam htg. sys., 
 
 advantages of, 169 
 
 automatic pump for, 172 
 
 Automatic system, 177 
 
 Paul system, 177 
 
 principal features of, 170 
 
 Van Auken, 175 
 
 Webster system, 173 
 Mechanical equivalent of heat, 11 
 Mechanical warm air heating and 
 ventilating sys., 117, 133, 148 
 
 blowers and fans for, 119 
 
 definitions of terms, 133 
 
 elements of, 117 
 
 exhaust, 118 
 
 heat loss and cu. ft. air exhausted, 
 134 
 
 theoretical considerations for, 133 
 
 variations in design of, 118 
 Mills system (attic main), 78 
 Modulation valve for Webster Bys- 
 
 tem, 175 
 Moisture, addition of, to air, 27 
 
 with air, 22 
 
 Naperian logarithms, table, 285 
 Nitrogen, 15 
 'n,' values of, 41 
 
 Operation of hot water heaters and 
 boilers, 
 
 of furnaces, 70 
 
 suggestions for. 114 
 Oxygen, 15 
 
 Paul sys. of mech. vac. heating, 177 
 typical piping connections for, 178 
 
 Pipe coil radiators. 83 
 capacity of, in sa. ft. of steam 
 
 radiation, 302 
 equalization, table of, 301 
 sizes, determination of, 99 
 
 Pipe, leader, 52, 66 
 
 Piping connection around heater 
 
 and engine, 161 
 
 connections for auto. vac. sys., 177 
 connections for Paul sys., 178 
 for heatg. sys. definitions, 74 
 system for automatic control of, 
 Webster system, 175 
 
 Pitot tubes, 30 
 
 Plans and sped, for htg. sys., 263 
 typical specifications, 264 
 
318 
 
 INDEX 
 
 return to boilers, 110 
 Condenser for exhaust steam, 210 
 
 heating surface in, 211 
 Conduction, 12 
 
 Conductivities of building materi- 
 als, 86 
 
 Conduits, central station htg., 185 
 Convection, 13 
 
 Conversion factors for water, 285 
 Data table for Dlenum systems, 164 
 Design, hot water and steam, 93 
 
 reports, instructions for 1, 2, 3, 
 258 
 
 reports, instructions for 4, 259 
 
 reports, instructions for 5, 261 
 
 Determination of pipe sizes, 99 
 Direct radiation, tapping list, table, 
 
 300 
 
 Dirt strainer, Webster, 173 
 District heating, 181 
 
 adaptation to private plants, 239 
 
 amount of radiation supplied, 208 
 
 amount supplied by reheater, 213 
 
 application to typical design, 239 
 
 boiler feed pumps, 221 
 
 by steam, 236 
 
 condensation from mains, 239 
 
 conduits, 185 
 
 cost of heating, 230 
 
 cost, summary of tests 232 
 
 diameter of mains, 205 
 
 economizers, 225 
 
 exhaust steam used in, 194, 210 
 
 future increase, 202 
 
 heating surface in reheater, 211, 
 213 
 
 high pressure steam heater, 216 
 
 important reheater details, 214 
 
 layout for conduit mains, 188 
 
 power plant layout, 231 
 
 pressure drop in mains, 203, 205, 
 237 
 
 radiation in district, 202 
 
 radiation supplied by 1 h. p. of 
 ex. st., 209 
 
 regulation, 235 
 
 scope of work, 183 
 
 service connections, 207 
 
 steam available for heating, 207 
 
 systems classified, 182, 200 
 
 typical design, 193 
 
 velocity of water in mains, 205 
 Division of coils, plenum sys., 129 
 Ducts, furnace, cold air, 53 
 
 plenum system, 129, 130 
 
 recirculating, 65 
 
 Economizers, 225 
 
 radiation supplied by, 225 
 
 surface, 226, 227 
 
 Efficiency of plenum coils, table, 139 
 Electrical heating, 253 
 
 formulas used in, 253 
 
 Exhaust steam available in district 
 
 plants, 194-199 
 
 Exhaust steam condenser, 210 
 Expansion joints, 190 
 
 tanks, 92 
 Exposure heat losses, table, 38 
 
 Factor table, velocity and vol., 152 
 Fans and blowers.. 70, 119 
 
 drives, 157 
 
 housings, 121 
 
 power of engine for, 159 
 Fire places, stoves, etc., 117 
 Fittings, steam and hot water, 89 
 Floor plans for furnace heating, 
 
 106-108 
 
 Floor plans for plenum sys., 165-167 
 Formulas, empirical for radiation, 96 
 Fresh air duct, 53-64 
 Fresh air entrance to bldgs., 123 
 Fuel values of Am. coals, table, 292 
 Furnace, 
 
 air circulation within room, 69 
 
 foundations, 64 
 
 heating, 45 
 
 location, 64 
 
 selection, 60 
 Furnace system, air circulation, 47 
 
 air required as heat carrier, 47 
 
 circulating duct in, 65 
 
 design of, 55 
 
 essentials of, 46 
 
 fan in, 70 
 
 fresh air duct in, 53, 64 
 
 grate area in, 63 
 
 gross register area in, 51 
 
 heat stacks, sizes of, 51, 67 
 
 heating surface in, 54 
 
 leader pipes in, 52, 66 
 
 net vent register in, 51 
 
 plans for, 57 
 
 points to be calculated in, 47 
 
 registers, temperatures in, 50 
 
 stacks or risers in, 67 
 
 three methods of installation, 49 
 
 vent stacks, 69 
 
 Gage pressures, 11 
 
 Grate area, boilers and heaters, 101 
 Grate area for furnaces. 53 
 Greenhouse heating, 97 
 
 Hammer, water, 110 
 Heat given off by persons, lights, 
 etc., 43 
 
 latent, 11 
 
 measurement of., 8 
 
 mechanical equivalent of, 11 
 
 stacks, sizes of, 51, 67 
 Heaters, hot water, 87 
 Heating, district, cost of, 230 
 Heating surface in coils, plenum sys- 
 tem, 137 
 
INDEX 
 
 Heating sur., in economizer, 226, 227 
 
 in furnace system, 54 
 
 in reheater, 211 
 
 per h. p. in reheater, 213 
 Heat loss, 37, 38, 39, 41, 134 
 
 calculation of, 35 
 
 combined, 41 
 
 for a 10 room house, table, 56 
 High pressure heater, 216 
 High pressure steam trap, 110 
 Horse power, in moving air, 154, 155 
 
 of engine for fan, 159 
 
 required to move air in plenum 
 
 system, 150 
 Hot air pipes, cap. of, table, 296 
 
 water heaters, 87 
 
 water pipes, capacity of, table, 302 
 
 water radiators, 85 
 
 water risers, cap. of, table, 303 
 
 water system, 72 
 
 water used in indirect coils in ple- 
 num system, 146 
 Hot water and steam heating, 
 
 calculations for rad. sur. for, 93 
 
 classifications, 75 
 
 determination of pipe sizes for, 99 
 
 empirical formula for, 96 
 
 grate area for heater, 101 
 
 greenhouse radiation, 97 
 
 location of radiators for, 102 
 
 parts of, 73 
 
 pitch of mains for, 102 
 
 principles of design of, 93 
 
 second classification of, 76 
 
 typical layout of, 103 
 Humidity of the air, 23 
 Humidities, relative, table, 291 
 Hygrodeik, 24 
 Hygrometer, 23 
 Hygrometric chart, 26 
 
 Indirect radiators, 76 
 Installation of steam pipes, 109 
 Instructions for design reports, Nos. 
 
 1, 2, 3, 258 
 
 for design report, No. 4, 259 
 for design report, No. 5, 261 
 'K,' values for pipe coils, table, 139 
 'K,' values for Vcnto coils, table, 
 
 141 
 
 outline of course in, 257 
 suggestions for course in, 256 
 
 Latent heat, 11 
 
 Layout for furnace system, 106 
 
 for hot water heating plant, 103 
 
 for plenum system, 127, 128 
 
 of power plant, 231 
 
 steam mains and conduits, 188 
 Leader pipes, 52, 66 
 Location of furnaces. 64 
 
 of radiators. 102 
 Low pressure steam traps, 110 
 
 Mains, condensation, dripping from, 
 239 
 
 cap. of hot water, table, 303 
 
 diameter of, 205 
 
 pitch of, 102 
 
 pressure drop and diameter of, 237 
 
 velocity of water in. 205 
 Manholes, 193 
 Measurement of air velocities. 29 
 
 of heat. 8 
 
 of high temperatures, 9 
 Mechanical vacuum steam htg. sys., 
 
 advantages of. 169 
 
 automatic pump for, 172 
 
 Automatic system, 177 
 
 Paul system, 177 
 
 principal features of, 170 
 
 Van Auken, 175 
 
 Webster system, 173 
 Mechanical equivalent of heat, 11 
 Mechanical warm air heating and 
 ventilating sys., 117, 133, 148 
 
 blowers and fans for, 119 
 
 definitions of terms, 133 
 
 elements of, 117 
 
 exhaust, 118 
 
 heat loss and cu. ft. air exhausted, 
 134 
 
 theoretical considerations for, 133 
 
 variations in design of, 118 
 Mills system (attic main), 78 
 Modulation valve for Webster sys- 
 tem, 175 
 Moisture, addition of, to air, 27 
 
 with air. 22 
 
 Naperian logarithms, table, 285 
 Nitrogen, 15 
 'n,' values of, 41 
 
 Operation of hot water heaters and 
 boilers, 
 
 of furnaces, 70 
 
 suggestions for. 114 
 Oxygen, 15 
 
 Paul sys. of mech. vac. heating, 177 
 typical piping connections for, 178 
 
 Pipe coil radiators. 83 
 capacity of, in sa. ft. of steam 
 
 radiation, 302 
 equalization, table of. 301 
 sizes, determination of, 99 
 
 Pipe, leader, 52, 66 
 
 Piping connection around heater 
 
 and engine, 161 
 
 connections for auto. vae. sys., 177 
 connections for Paul sys., 178 
 for heatg. sys. definitions, 74 
 system for automatic control of, 
 Webster system, 175 
 
 Pitot tubes, 30 
 
 Plans and speci. for htg. sys., 263 
 typical specifications, 264 
 
320 
 
 INDEX 
 
 Plenum system, actual amount of 
 air exhausted in, 152 
 
 air needed cu. ft. per hour in, 136 
 
 air velocity, table, 136 
 
 air velocity theoretical in, 148 
 
 air washing and humidifying, 131 
 
 amount of steam condensed, 146 
 
 application of to school bldgs., 162 
 
 approximate rules for, 142 
 
 approximate sizes of fan wheels, 
 table, 156 
 
 arrangement of coils in pioe heat- 
 ers, 144 
 
 arrangement of sees, and stacks in 
 Vento heaters, 145 
 
 basement plans for, 165 
 
 blower fans actual h. D. to move 
 air, 155 
 
 Carpenter's rules for, 155 
 
 cast surface for, 126 
 
 coil surface in, 124, 125 
 
 cross sectional area ducts, regis- 
 ters, etc., 136 
 
 data, table, 164 
 
 division of coil surface in, 129 
 
 double ducts in, 130 
 
 dry steam needed in excess of exh. 
 from engine, 147 
 
 efficiency and air temp., table 139 
 
 factors for change of velocity and 
 volume, table, 152 
 
 fan drives for, 157 
 
 final air temperature in, 142 
 
 floor plans for, 165-167 
 
 heating surface in coils of, 137 
 
 heating surfaces, 124 
 
 h. p. of engine for fan for, 159 
 
 h. p. to move air, table, 150 
 
 'K,' values of, 138 
 
 layout, 127, 128 
 
 piping connections around heater 
 and engine, 161 
 
 pressure and velocity, results of 
 tests of, 153 
 
 single duct in, 129 
 
 speed of blower fans, table, 158 
 
 speed of fans for, 157 
 
 temp, of air at register in, 135 
 
 temp, of air leaving coils, 143 
 
 total B. t. u. transmitted per hr., 
 table, 140 
 
 use of hot water in indirect coils, 
 146 
 
 values of 'K,' 138 
 
 velocity of air escaping to atmos- 
 phere, table, 151 
 
 work done in moving air, 154 
 Power plant layout, 231 
 Pressed steel radiators, 84 
 Pressure, absolute, 11 
 
 and velocity, results of tests, 153 
 
 gage, 11 
 
 in ounces per SQ. in., table, 298 
 
 water in mains, 203 
 
 Principal features of mechanical vac- 
 uum heating system, 170 
 Properties of air, 290 
 Properties of steam, table, 278 
 Pumps, boiler feed, 221 
 
 centrifugal, 219 
 
 circulating, 216 
 
 city water supply, 221 
 
 for mech. vac. steam heating, 172 
 
 Radiation, 12 
 
 amount of one sa. ft. reheater 
 tube surface will supply, 213 
 
 amt. supplied by economizer, 225 
 
 amt. supplied by one h. p., 224 
 
 hot water, 85 
 
 one Ib. exh. steam will supply, 208 
 
 supplied by 1 h. p. exh. steam, 209 
 
 sur. to heat circulating water, 226 
 
 surface to heat feed water, 227 
 Radiators, amt. of surface on, 86 
 
 cast, 83, 84 
 
 classification of, 82 
 
 columns of, 83 
 
 direct, 75 
 
 direct-indirect, 75 
 
 height of, 85 
 
 indirect, 76 
 
 location and connection of, 102 
 
 pipe coil, 83 
 
 pressed steel, 84 
 
 sizes, etc., for ten room house, 
 table, 105 
 
 sizes, table of, 86 
 
 steam, 85 
 
 surface calculation for, 93 
 
 sur. effect on trans, of heat, 86 
 Recirculating duct, 65 
 Register, area of. 51 
 
 diameter of. table, 294 
 
 ducts, area of, 136 
 
 sizes, net heat, 50 
 
 temperature, 50 
 Regulation, district heating, 235 
 
 Sylph on damper, 245 
 Room temperature, standard, 42 
 
 Service connections, 207 
 
 Single duct, plenum system, 129 
 
 Sizes of fan wheels, approximate, 
 
 table, 156 
 
 Smoke flues, equalization of, 294 
 Specifications for plans, 257, 264 
 Specific heat, 12 
 
 heats, etc., of substances, 295 
 Speeds of blower fans, 157, 158 
 Squares, cubes, etc., table, 271 
 Stacks and risers. 67 
 Standard room temperature, 42 
 Steam and hot water fittings, 89 
 
 available for heating circulating 
 water, 207 
 
 boilers, 87 
 
INDEX 
 
 condensed per SQ. ft. of heating 
 
 sur. per hour, plenum sys., 146 
 dryf needed in excess of engine 
 
 exhaust, 147 
 
 heater, high pressure, 216 
 heating, district, 236 
 pipe installation, 109 
 radiators, 85 
 traps, high pressure, 110 
 Steam system, 72 
 
 amt. condensed in plenum sys., 146 
 classification, 75 
 parts of, 73 
 
 second classification of, 76 
 Street mains and conduits, layout, 
 
 188 
 Suggestions for operating hot water 
 
 heaters and boilers, 114 
 for operating furnaces, 70 
 Sylphon damper regulator, 245 
 
 Table I determination of COa, 19 
 Tables II, III volume of air per per- 
 son, 21 
 Table IV conductivities of materials, 
 
 36 
 
 Table V exposure losses. 38 
 Table VI values of t 1 , 42 
 Table VII values of t=> , 43 
 Table VIII heat given off by per- 
 sons, lights, etc., 43 
 Table IX application, to 10 room 
 
 res., 56 
 
 Table X size and sur. of rads., 86 
 Table XI temi>. of water in mains, 
 
 99 
 
 Table XII summary, h. w. htg., 105 
 Table XIII vel. in plenum sys., 136 
 Tables XIV-XVII efficiencies of coils, 
 
 139-141 
 Tables XVIII-XIX temp, of air on 
 
 leaving coils, 143 
 Tables XX-XXII air pressure and 
 
 velocity, 150-152 
 Table XXIII sizes of fans. 156 
 Table XXIV speeds of fans, 158 
 Table XXV data for plenum sys., 164 
 Table XXVII pressure of water in 
 
 mains, 205 
 
 Table XXVIII cal. of conduit mains, 
 241 
 
 Table 
 Table 
 Table 
 Table 
 
 Table 5 
 Table 6 
 Table 7 
 Table 8 
 Table 9 
 Table 10 
 Table 11 
 
 squares, cubes, etc., 271 
 properties of steam, 278 
 Naperian logarithms, 285 
 water conversion factors, 
 
 285 
 
 vol. and wt. of dry air, 286 
 weight of pure water, 287 
 boiling points of water, 289 
 weight of water and air, 289 
 properties of air, 290 
 relative humidities, 291 
 fuel values of Am. coal, 292 
 
 Table 12 capacities of chimneys, 293 
 Table 13 equalization of smoke flues, 
 
 294 
 
 Table 14 diameter of registers, 294 
 Table 15 sp. ht., etc., of substances, 
 
 295 
 
 Tables 16, 18 cap. of fur., 296, 297 
 Table 17 cap. of pipes and reg., 296 
 Table 19 area vertical flues, 297 
 Table 20, 21 water pressures, 298 
 Table 22 wrought iron pipes, 209 
 Table 23 expansion of pipes, 300 
 Table 24 tapping list of rad., 300 
 Table 25 pipe equalization, 301 
 Table 26 capacities 1 of hot water 
 
 risers, 302 
 
 Table 27 cap. of steam pipes, 302 
 Table 28 cap. of hot water pipes, 303 
 Table 29 cap. of hot water mains, 303 
 Tables 30 31 sizes of steam mains. 
 
 304 305 
 Table 32 loss of head by friction ol 
 
 pipes, 306 
 
 Table 33 expansion tanks, 307 
 Table 34 sizes of Vento heaters, 307 
 Table 35 heat trans, through pipe 
 
 coverings, 308 
 
 Tables 36, 37, 38 speeds, cap. h. p. of 
 various' fans, 309-312 
 Table 39 dim. of ells and tees, 313 
 Tanks, expansion, 92 
 Temperature absolute, 10 
 
 measurement of high, 9 
 
 of air entering plenum system, 135 
 
 of air in greenhouses, table, 99 
 
 ol air leaving coils in plenum sys- 
 tem, 143 
 
 room standard, 42 
 Temp, control in heating sys., 243 
 
 Andrews system, 244 
 
 important points in, 247 
 
 in large plants, 246 
 
 Johnson system, 248 
 
 thermostat, 244 
 
 National system, 251 
 
 Powers system, 249 
 
 principle of system, 243 
 
 special designs of, 247, 252 
 
 Sylphon damper control, 245 
 Thermofiers, Belvac, 175 
 Thermostat, 244 
 
 thermostatic valve. 174 
 Traps, high pressure steam, 110 
 
 low pressure steam, 110 
 
 Under- fed furnaces. 62 
 
 Use of hot water in indirect coils 146 
 
 Vacuum systems, 79, 169 
 Values of V. 140 
 
 of 'k,' 36, 141 
 
 of 'n.' 41 
 
 Of 't.' 42, 43 
 
INDEX 
 
 Valves, air. 91 
 
 automatic vacuum. 177 
 
 modulation valve. 175 
 
 thennostatic, 174 
 
 types of, 192 
 
 Velocity of air by application of 
 heat, 28 
 
 of air escaping to atmosphere, 151 
 Vent registers (net), 51 
 
 stacks, 69 
 Ventilation heat loss. 88 
 
 air required per person, 19 
 Vento coils, values of 'k' for. 141 
 Vertical hot air flues, table. 297 
 Volume and wt. of dry air, table, 286 
 
 Warm air fur., cap. of, table 296 
 air heating cap., 297 
 
 Washing and humidifying of air, 131 
 Water, conversion factors, table. 285 
 
 hammer, 110 
 
 needed per hour in dist. htg., 201 
 
 pressure in mains. 203 
 
 pressure, table of. 205 
 
 seal motor, Webster. 173 
 
 weight of column corresponding to 
 air pressure in ozs.. 298 
 
 weight of pure, table of. 287 
 
 weight of water and air. table, 289 
 Weight of pure water, 287 
 
 of water and air. table. 289 
 Work done in moving air, 154 
 Wrought iron and steel pipes, table, 
 299 
 
 expansion of. table, 300 
 

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