QJorncll lIlnioctBity Htbrarg 3tl;aca. ^em ^ark THE LIBRARY OF EMIL KUICHLING. C. E. ROCHESTER. NEW YORK THE GIFT OF SARAH L. KUICHLING 1919 Cornell University Library TH 7225.S39 1901 A manual of heating and ventilation, in 3 1924 004 982 710 The original of tliis book is in tlie Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924004982710 A MANUAL HEATING AND VENTILATION, IN THEIR PRACTICAL APPLICATION, FOR THE USE OF ENGINEERS AND ARCHITECTS. EMBRACING A SERIES OF TABLES AND FORMULAS FOR DIMENSIONS OF HEATING FLOW AND RETURN PIPES, FOR STEAM AND HOT WATER BOILERS, -FLUlES, ETC., ETC. F. SCHUMANN, C. E., CORRESPONDING MEMBER OF THE AMERICAN INSTITUTE OF ARCHITECT^ AUTHOR OF "FORMULAS AND TABLES FOR ARCHITECTS AND ENGINEERS." FOURTH EDITION, REVISED AND ENLARGED. NEW YORK: D. VAN NOSTRAND COMPANY, 23 MURRAY AND 2? WARREN STREETS. I9OI. COPYRIGHT, 1877. 9t D. VAN NOSTRANDb PREFACE In the following pages it is my object to give con- cisely, the formulse and data necessary for computing the proper dimensions, etc., of Heating and Ventilating appli- ances, with a brief statement of the general principles upon which they are based. It is not intended as a theoretical work, but as a vade- mecum or book of reference for those having the neces- sary theoretical knowledge, and requiring a convenient and handy book containing the results of theory, relative to the subject, in a form suited for practical application. The deductions of European authors, made use of, have been modified to suit the conditions of our climate, prac- tiia, etc. In this second edition I have added practical rules and tables for determining size of boiler, grate surface, diameter of steam and hot-water pipes, and radiating surface for both hot-water and steam apparatus. Trenton, N. J., March, 1886. CONTENTS. PREFACE— .... GENERAL PRINCIPLES — Direct Radiation, Indirect Radiation, Ventilation, ... Mechanical Ventilation, Vacuum Movement, Plenum Movement, Mixed Movement, Currents, Proper Velocities of Currents, Loss of Heat in Ventilated Rooms, Sources of Heat in Ventilated Rooms, VENTILATION — Air Supply, ...... 18 Air Vitiated, 18 Carbonic Acid, - - - 21 Flow of Air in Aspiiating Chimneys or Veutilating Shafts, 21-253 Coefficients of Friction (Air), - - 23 Fans for Vacuum or Plenum Movement, According to Rittinger, 26 " " " " " Combes, 28 Steam Jet, ..... yg • 7 • . • 8 9 - 10 ID 10, 13, 14 10, 15 • , " 10 10 ■ _ " 11 16 s, - - i5, 17 HEATING — General Principles, ... Unit of Heat, Specific Heat, .... Transmission of Heat, Loss of Heat, or Cooling of Bodies, Loss of Heat by Radiation, Radiating and Absorbing Power of Bodies, Loss of Heat by Contact v/lth Air, Loss of Heat by Conduction, - • 31 3« 31 31 31 32 33 34 34 VI CONTENTS. Loss of Heat through Walls and Windows, • - 3S> 3^ Loss of Heat through Floors, .... 35 Lross of Heat through Ceilings, - - - - 3S Conducting Power of Materials, - - - 37 Loss of Heat by Incoming Fresh Air, - - -39 Hot Water Pipes, Units of Heat Emitted or Absorbed by, 39 Steam Pipes, Units of Heat Emitted or Absorbed by, 40 Units of Heat Required to Heat i Cubic Foot of Air, 41 Specific Heat of Bodies, ..... 42 Weight and Volume of Water of Different Temperatures, 42 Weight and Volume of Dry Air, - - - 43 Heating with Hot Water — General Principles, ------ 45 Diameter of Pipes, etc., ... 47 Flow of Water in Pipes, - .... 48 Friction in Elbows or Connections, - . - 51 Coefficient of Friction for given Velocities, - - 52 Dimensions of Boilers, Grates, etc., - . . 54 Heating with Steam — General Principles, - . . . jg Diameter of Pipes, etc., .... 60 Dimension of Boilers, Grates, etc., ... 61 Temperature of Steam in Boiler, and Pressure per Sq. Inch, 63 Flow of Steam in Pipes, - . • . 83 Combustion of Fuel — - .... 66 To Estimate the Theoretical Units of Heat in i lb. of FueV 67 Net Weight of Air Necessary for Complete Combustion, - 67 Efficiency of Furnaces and Boilers, . - 68 Protortion of Smoke Chimneys, - - . 69 HVGROMETRY — Humidity of Air, -••.,. 70 Elastic Force of Vapor of Water, ... 73 Evaporation, --.....75 ADDENDA— 85 Loss of Heat through Walls, . . . - 85 Loss of Heat through Windows, ... g6 Notes, 87 Boilers, - ..... 87 Temperatures in the U. S., Table of, ... gg Practical Rules and Tables for Hot-Water Apparatus, - go Practical Rules and Tables for Steam Apparatus, - "93 HEATING AND VENTILATION. GENERAL PRINCIPLES. Hot water apparatus, where the temperature in the boilei does not exceed 2 1 2°, should be adopted for buildings occupied continuously, and where steam from power boilers is not availa- ble, for instance : Schools, Court rooms. Hospitals and Dwell- ings ; steam on the other hand, for Churches, Theatres, Public Halls occupied at intervals, and such other buildings where steam is used as power and the application of the waste for heating purposes is practicable. The choice of Direct or Indirect radiation, will depend on the construction of the building, and on the purposes for which it is intended. It is sometimes impossible to obtain sufficient space in walls for heating flues ; or it may be objectionable to supply the radiators in the cellar or basement with air that might be contaminated by being taken from near the sidewalk or damp and unclean areas, when it would be an easy matter to supply direct radiators through openings in window breasts ; on the other hand, direct radiators in a room may interfe?e with the decorations, or it may be difficult to supply the fresh air. Direct radiation is the most economical, for the reason that radiant heat is utilized, while in indirect radiation it is partially lost HEATING AND VENTILATION. DIRECT RADIATION. In direct radiation, the coils or radiators R, are placed in the room (if possible on the coldest side) they are intended to warm ; the fresh air being conveyed to them, through flues F, to the lowest part of the coils, the flow of air being regulated by a damper D. The fresh air is heated by contact with the radiators R, tlie r I- surrounding walls and solid objects absorbing a certain amcjunt of radiant heat and again heating the air by contact. Radiant heat does not heat the air through which it passes, to any appreciable extent. The intensity of heat emitted by a plane surface, decreases with the sine of the angle formed between the direction of the rays, and the surface at the point of emission ; therefore circular surfaces are more effectual than plane ones. GENERAL PRINCIPLES. INDIRECT RADIATION. In indirect radiation, the coils cr radiators are placed in other rooms than those they are intended to heat, generally the basement or cellar as at R, the fresh air being conveyed to them through flues or ducts F, and heated by contact, and thence through flues or ducts F„ into the various rooms ; the quantity of cold air being regulated by dampers D. The walls and solid objects in the rooms are heated by contact with the warmed air only. Arrows show direction of currento. 1* 10 HEATING AND VENTILATIOM. VENTILATION. Ventilation is either natural or mechanical or both, the first being by means of openings, such as windows, doors, etc. ; the second, by means of fans or chimneys, and the third, both combined, generally for summer ventilation. MECHANICAL VENTILATION. Vacuum Movement: Aspirating chimneys exhaust the air from the rooms, thus creating a partial vacuum for the pure air to occupy, coming in through the proper openings. The move- ment of the air in the chimney is produced by heating and rarefying the air in it ; the external air, being heavier, tends to push it up out of the chimney ; the fire or heater should be at the lowest point of the chimney. Exhaust fans fulfill the same functions as aspirating chimneys ; they may be located under the roof, or in the cellar — the foul air from them being conveyed, through ducts or shafts, away fi-om the building. The vacuum movement requires the doors and windows to be kept closed, during cold weather, so that the fresh air is forced to pass through the heating coils ; it has the disadvantage of causing inward draughts through crevices, etc. Plenum movement : The air is forced in from without by means of fans, the foul air passing off" through outlets in walls or ceiling. In rooms so ventilated, there is a slight outward pressure,- neutralizing any inward draughts, except through the proper channels. Mixed movement: Is a combination of the vacuum and plenum, and is applicable when one or the other is not of sufficient power. CURRENTS. Currents in ventilated rooms, are either directed upward or downward ; in the upward direction, the pure air is admitted at or near the floor, the impure air passing off at or near the GENERAL PRINCIPLES. 11 ceiling. In the downward direction, the pure air is admitted at or near the ceiling, or through inlets in the walls near the floor, and the impure air, passing off through the floor, or openings in the walls near the floor. Public places above 15 ft. high, where large crowds assemble, should have the upward direction ; smaller rooms, offices, dwellings, etc. may be ventilated down- wards. The pure air inlets should be equally distributed around the room, with the outlets for the impure air, in such position, as to cause the currents to sweep the whole room, being careful for instance, not to place an outlet directly over an inlet. In the upward movement, the inlets may be in the floor, in risers of platforms, in sides of walls near the floor, in stationary desks, and in the front of stationary benches, etc., etc., etc. The outlets may be in the cornice, or ceiling, or side of walls near the ceiling. This method requires no changes with the sea- sons — the fresh air, in summer, entering in the same way that it does in winter, when the coils are heated. In the downward movement, on the other hand, the fresh air, in summer, may be admitted at or near the floor, and passed off", at or near the ceil- ing. Where windows are available, and so placed that cur- rents pass through the room, no provisions need be made in either method for summer ventilation except when there is an object to keep them closed to exclude noise and dirt. PROPER VELOCITY OF CURRENTS, IN FEET, PER SECOND. FEET. When entering at or near the ceiling and descending, 1.8 When entering at or near the ceiling and horizontal, 4.0 (when the openings are not less than 12 ft. above the floor.). When entering at or near the floor, maximum 2.0 In ducts, shafl:s, etc 3 to lo.o To illustrate the theory of ventilation, let us assume a room to be filled with colored water, to represent vitiated or foul «r, 12 HEATING AND VENTILATION. and the room to be completely submerged in clear water, to represent pure or external air. As air and water are subject to the same laws in regard to flow, it follows: First: If the room be perfectly tight, there will be no ex- change or mixture between the colored and clear water, and consequently no ventilation. Secondly : If openings be provided on sides, top and bottom of the room, the colored and clear water- having the same tem- perature, no mixture or ventilation will occur, except tlirough gradual diffusion equally through all openings. Thirdly : If the clear water be of a higlier temperature than the colored, the colored water will flow out of die lower open- ings, it being heavier, and the clear water will enter through the upper openings, filling the room, as the colored water leaves it. Fourthly : If the clear water be of a lower temperature than the colored, it will enter through the lower openings, pushing the colored water, which is lighter, out of the upper openings. From the above it follows, that : In cold weather, when the temperature of a room is higher than the external air, the air 1 should be admitted at the iiiiltttr ExUrnal Air warmer Ceiling Fresh Air I Foul Air ! Boom Y "i Y i External Air colder bottom, and passed off at the top of a room ; on the other hand, in warm weath- er, when the temperature of the room is lower than the external air, the pure air should be admitted at the top, and passed off at the bottom, thus. See Fig. 5. The movement as explain- AiTows show direction of currents. ed abovc, Can be revcrscd by either the vacuum or plenum methods, when desirable, but, if possible, the movements caused by artificial means, should "fTTT Fig.5 GENERAL PRINCIPLES. 13 coincide with and assist those effected by nature (gravity), it being certainly more economical, when perfect ventilation is required. VACUUM MOVEMENT. Fig. 6 represents a section through a building showing the application of different kinds of heating and ventilation. Fig.6 A section through a building. Airows show direction of currents, {Direct radiation, \ Currents ( Indirect radiation , J currents downward. ) upward. ( currents downward. ) Reference : — A, fresh air duct. B, direct radiators. C, indirect " D, coils in ridge for assisting ventilation by rarefying the ail at the outlet of ventilating flues. 14 HEATING AND VENTILATION. Fig. 7 is a section through a building having an aspirating and a supply shaft. Ventilation : Vacuum movement ; Heating: Indirect radiation; Currents : Upward direction. Reference : — A, fresh air supply shaft. B, duct conveying fresh air to coils. C, coils. D, duct conveying foul air to chimney. E, fire and grate. F, aspirating chimney. GENEERAL PRINCTPLES. 15 PLENUM MOVEMENT,. Fig. 8 is a section through a building showing the arrange- ment of supply sliaft, fan, radiator ox coil, and ridge venti- lation. Arrows show direction of currents. Ventilation: Plenum movement ; Heating: Indirect radiation; Currents: Upward direction. Reference : — A, is the fresh air supply shalL B, duct leading to fan. C, the fan, D, duct leadmg from fan to coils. E, heating coils under the room. F, flues transmitting the heated air to room. G, room. H, outlets in ceiling. K, coils in roof ventilator, to prevent the cold air from, coming in. 16 HEATING AND VENTILATION. Loss OF HEAT in ventilated rooms is caused by :— ist. Units of heat required to warm the air passing through the room. 2d. Units of heat absorbed by surrounding walls. 3d. Units of heat absorbed by ceiling. 4th. Units of heat absorbed by floor. 5th. Units of heat absorbed by windows. Sources of heat in rooms are : — I St. Units of heat generated by the occupants. 2d. Units of heat generated by the gas-hghts, oil lamps and candles. 3d. Units of heat generated by the heating apparatus. It has been found by experience, that an adult man requires hourly, for respiration and transpiration, 215 cubic feet of at- mospheric air, or 215X0.077 = 16.5 lbs., and generates about 290 units of heat, of which 99 units are dissipated in the forma- tion of vr.por, leaving 191 units to be dissipated by radiation to the surrounding objects, and by contact with colder air. The quantity of air required, and the heat generated by gas Hghts, can be estimated with sufficient approximation for prac- tical purposes. The specific gravity of gas, is about J^ that of atmosphenc air, or 0.038 lbs. per cubic foot, and requires for complete combustion, 0.038X17 =0.65 lbs. of air, or — '-^ 0.077 = 8.44 cubic ft. Each cubic foot of gas burned emits about 600 units of heat. An oil lamp with a moderately good wick, consumes about 154 grains per hour = 35 lamps per pound. Each lb. of oil demands 150 cubic ft. of air for complete combustion and gen- erates about 16,000 units of heat, or 460 per lamp. Candles, 6 to the lb. may be reckoned the same as a lamp consuming oil, each candle burning about 170 grains per hour. GENERAL PRINCIPLES. 17 These data tabulated, give in round numbers ; An adult man vitiates per hour 2x5 cubic ft. Every cubic foot of gas burned 8.5 " " Every lb. of oil burned 150 " " Every lb. of candles, 6 to a lb 160 " " Units of heat generated by an adult, per hour 191 Units of heat generated by one cubic ft. of gas 600. Units of heat generated by one lb. of oil or candles 1 5,000 to 18,000. An average gas burner consumes about 4 feet of gas per hour = 600X4 = 2,400 perbumer 2400 units per hour, Each flame from an oil lamp 430 to 5 1 5 " " Each candle 454 to 545 " * !•• VENTILATION. AIR SUPPLY. Air vitiated: — ^The following are some of the vitiating causes: I St. Respiration and transpiration of human beings. 2d. Respiration and transpiration of animals. 3d. Burning of candles, oil lamps and gas-lights. 4th. Operations generating smoke. 5th. Operations generating dust and its disturbance. 6th. Mechanical and chemical processes generating steam and gases. An adult man, under ordinary circumstances, requires for respiration and transpiration, 215 cubic ft. per hour, to be mul- tiplied by a factor so that the per cent, of vitiation shall not ex- ceed certain limits. Every cubic foot of gas consumed, requires for complete combustion, and that the air remains pure, 1,800 cubic ft. per hour. I Every pound of oil or candles consumed, 18,000 cubic ft. of air per hour, or ten times as much as gas. Air supply : — ^The following formulse will demonstrate the necessity of a greater supply of pure air than is vitiated by an adult per hour, so that the percentage of vitiation will not ex- ceed certain limits, say from 5 to 15 per cent. VENTILATION. 19 Let V = Volume of fresh air in cubic ft. to be supplied per hour. V = Volume of air vitiated per hour = 215 cubic ft. per adult, p = Per cent, of vitiation admissible. C = Cubic contents of room to be ventilated. — = ; V = v ; v = ; p = .^^ , ; hence V p p 1— p*^V + v P when p = 0.02 0.03 0.04 0.05 0.06 0.07 0.08 V will be 49 33 24 19 16 13 12 0.09 o.io o.ii 0.12 0.13 0.14 0.15 10 9 8 7 6.7 6 5.6 times V respectively; consequently, a room, to contain not more than from 1 5 to 2 per cent, of vitiated air, must be sup- plied with from 5.6 to 49 times more fresh air than is vitiated, plus the quantity required for illuminating purposes. The following are some values for p, when v = 2 1 5 cubic ft. per hour : Barracks and Dwellings, p = 0.15 by day; p = o.io by night. Workshops p = o.io Prisons p ^ o.io Theatres p = o.io Schools p = o. 1 5 Hospitals p ^ 0.07 by day and night. " p = 0.05 during hours of dressing. " p = 0.04 during epidemics. Example : — A hall, 40 x 40 x 20=32,000 cubic ft., having 30 occupants, and illuminated by thirty gas lights, each consuming 4 cubic ft. of gas per hour, how much pure air must be supplied per hour so that the limit of vitiation shall not exceed 0.10 per cent. ? 20 HEATING AND VENTILATION. v = 215X30 = 6450 V =v = 6450 = 6450x9 = 58050 cubic ft. for the occupants, and for illumination per hour 1800X30X4 = 216000 cubic ft. Total, per hour 274050 cubic ft. 27401^0 The air in the hall changing — — =^ = 8.56 times per hour, and the inlet areas required, for a velocity of r.5 ft. per , 2740150 274050 . second = ' ^.^ . = ' ^ = 50.7 sq. ft. 1.5x60x60 5400 •' Carbonu acid : — ^The per cent, of carbonic acid contained m the air of a room, should be as near to that contained in air of normal condition, viz., 0.04 per cent., as can be practically obtained by means of ventilation; it should not exceed 0.06 per cent., for rooms continually occupied; when it reaches 0.09 per cent., the air becomes disagreeable to the senses. To compute the per cent, of carbonic acid in the air of a room supplied with fresh air as per foregoing formulas, Let p, = Per cent, of carbonic acid in the room, with continu- ous ventilation, pj = Per cent, of carbonic acid in normal air = 0.04. c = Carbonic acid given out by an adult man per hour = 0.6 cubic ft. q = Volume of air in cubic ft. per man, per hour. Then wUI : q = ^^ zoo ; and Pi = ^ (c-p.) +p^ VENTILATION. 21 Example: — p = a.io; q = 415X9 = 1935) 100 / -; » , 100X0.56 p, = (0.6—0.04) +0.04 = ^- +0.04 = 0.0680, a «93S 193s little more than the standard of 0.06 per cent. To reduce 0.6—0.04 It to 0.06 per cent., q would have to equal — 100 0.06—0.04 ■» — 100 = 2800 cubic ft. per hour, per man. '5.02 FLOW OF AIR IN ASPIRATING CHIMNEYS OR VENTILATING SHAFTS. Reference:— See Figs. 9 to 9I. h = Height of chimney ^lii + lij. 1 = Total length of ducts = h + h, + l, + l, f= Coefficient of friction in ducts, etc. f,= " " in elbows, etc. 22 HEATING AND VENTILATION. g = Accelerated gravity = 32.166 ft. e = Expansion of air per 1° temp. = 0.00208. A = Sectional area of duct, etc. p — Periphery of area. u = Units of heat in i lb. of coal on grate A. % = Per cent, of loss by radiation through walls of chimney. k = Number of lbs. of coal used per hour. s= Specific heat of air = 0.238. U = Units of heat per hour in chimney. W = Weight of air in lbs. carried oflf per hour. V = Volume of air passing through chimney per hour, w = Weight of a cubic ft. of air of the internal temp., t^ V = Velocity of air in ft. per second in ducts. t = External temperature. t, =; Internal temperature in room. t,= " " in chimney. tj = Increase of temperature in chimney, by fire, etc _ / e(t,-t). 2gh ^_ v'(^+et){x+f^+f.} U = u%lc; t3 = ^; W=Vw; k=^; t, = t,+t. ; A vMr+et){x+f-+f.} V = 36ooAv: A= , 3600V u, generally for coal = 6000. % = 0.90. -(t.->t); d = ^, V VENTILATION. 23 For Figs. 9a to gd: Jfig- So Fig>9d. / (t, -t)h,+ (t,- t)h. I +et, A-U, "1 t2 nil- h t Fig. 9s For Figs, gf to gi : Fig. eyx / iU - t) h v = o.366V 1 ; i + fj+f.' I +et, I + et ' 24 HEATING AND VENTILATION. 1-u, jt>, f2 T^ t2 1 ^ t- M ^1 t,--f- k. ^fs| M n \ Fiff. 9Ii yig. SI For Figs. 9k and 9 1: /(t,- - t) h, + (t, - t,) h. v = 0.366 Y i + f^ + f. ' V ^ + ^ ^ I + et COEFFICIENTS OF FRICTION. 0.217 f = 0.024; or " ; for rougli flues f = 0.05. V V Air passing from a smaller to a larger flue, through an opening in a wall, Fig. 10. ^'s-\o A, A,, Aj, = areas of flues, etc.; a = 0.60 ■ WhenA> A„f.= {^_xj'. \\ ^^ ( A,a ) whenA. = A, say 0.50. Air passing through a wall or plate, Fig. 12. Fig.l2 f. = 0.50. Square Elbow, Fig. 13. Circular Elbow, Fig. 14. 4 = i-So- f. = 0.50. FLOW OF AIR IN ASPIRATING CHIMNEYS OR VEN- TILATING SHAFTS. Example : — See Fig. 9. Shaft and ducts square. Let u ^ 6000 X 0.90 = 5400. s = 0.238. h = 150 ft. hj = 100 ft. /- = S X S = 25 sq. ft. VENTILATION. 25a / (70— 30) 20 + (l( V^ 0.366 \/ 100 ' I + 0.07 (100 — 30) 80 + 0.07 h 0.5 2 0.366 ./ 800 + 5600 _ „ 66 /6 T I + 3-5 + o-s y 6400 5 ^ 0.366 X 35-7 = 13.066 feet per second. Example:— What is the velocity in shaft as per Fig. gi? Dimensions, etc., same as above, except that tj = t = 30°, and h = h^ ^ 80 ft. Hence :— V = 0.366 4/(i°°EM8^= ^.366 /i6^o K 1 + 3-5 + 0.5 V 5 = 0.366 X 33-5 = 12.26 feet per second. Should the fire or heater be at the bottom, h = 100 ft., v becomes 0.366 ./(t°°-3°) i°°= 0.366 i/7°°° T I + 3-5 + o-S T 5 = 0.366 X 37.4 = 13.7 ft. per second. Example: — In shaft as per Fig. 9k, having the following dimensions: — h,^ 80; h, ^ 20, and t ^ 30"; tj= 70"; t.,= 100° assuming a frictional resistance of 5, V = 0.366 i/(l 00 — 30) 80 4- (100 — 70) 20 S 600 = 0.366 X 35.2 = 12.88 ft. per second. 26 HEATING AND VENTILATION. FANS. VOR VACUUM OR PLENUM MOVEMENT, ACCORDING TO RITTINGER. Reference: — See Fig. 15. V = Volume of air delivered in cubic ft. per second. h = Height manometer, in duct, in feet ; generally 0.05 to 0.6 feet. c = Velocity of the air entering the fan. c. = Velocity of the air leaving the fan. r = Outer radius of vanes, r, = Inner radius of vanes, r^ = Radius of inlet. 1 = Radius for the curve of vanes, b = Width of vanes, a = Height of outlet, a, = Distance from vertical radius to point e,. VENTILATION. 27 n := Number of revolutions per minute. z° = Angle between radius and initial line of vane. Hp = Horse power required. When there is only one inlet, When there are two inlets, Ta ^ -A > "■ » ^^ "v » V c;r * 2c;r J. 3 r ° 2/Tr,C r, = r, to 2r,; ""^^V-^ r"— r' . nr 1 = T-^ — , in which the tangent z° = 0.1047 — ^ describes 2r, sm. z° c a curve from the point e, to the inner periphery of vanes. a = — I in which c, = _/ < - c | +0.01 1 n'r' ; a, = 0.159 a; The^ of effect is generally from 30 to 60, therefore for 40^ Hp = ^l^Vh = o.28Vh. 55° 4° The shell of this fan has the form of an archimedean spiral, beginning at point e. The number of vanes = lorj, generally 4 to 6. c = 10 to 40 ft. per second. Example : — How many horse power are required to deliver 260 cubic ft. of air per second, when h = o.i ? Hp = o.28Vh = 0.28x260X0.1 28 HEATING AND VENTILATION. FANS. FOR VACUUM OR PLENUM MOVEMENT, ACCORDING TO COMBES. Reference: — See Fig. i6. A = Sectional area of air current, as it leaves the fan. A. = Sectional area of air current, as it enters the fan. Aj = Sectional area of delivery duct. V= Volume of air delivered in cubic ft. per second, theoretical quantity. V, = Volume of air delivered in cubic ft. per second, actual quantity passing through the duct. b = Width of fan, outside. b, = Width of fan, inside. c = Velocity of air entering the fan, theoretical. c, s= Velocity of air leaving the fan, theoreticaL VENTILATION. 29 c, = Velocity of air leaving the fan, actual, from 6 to 20 ft. d = Outer diameter of fan. d. = Inner, diameter of fan. _ Column of air 28133 Column of water ~ 33-95 ~ g = Force of gravity = 32.166 ft. h = Height of manometer, from 0.025 ^° °-^ ^^• k = Per cent of effect, from 20 to 50. 1 = Radius for vanes = ^d to §d. n = Number of revolutions per second, from i to 2. r = Outer radius of vanes, r, = Inner radius of vanes, v = Velocity of periphery of vanes. f aM z° = Angles between tangents and initial line of vanes. Hp = Horse power required. V c = Vzghe approx. = -- =v, generally from 6 to 30 ft Aj c° h = — ; V = dn;r : A = db;r sin z"; 2ge A, = dib^TT sin. z," ; — ^^ ^' ^ . — -Xi Z££ . r b sin. z° ' ~ Ac, k ' It- ]r too V.=V— =nAc.— ; V = n Ac. = V. -j- ; ' 100 100 k 62. sVh 62.sV,h 100 .,„ Hp = — ^ — = — 2-^ X -j- =o.ii3Vh ^ 55° 55° k 100 = o.ii3V,h — ; ^ = A, = b.d,7r = bd;r; b = b.i; b.=b^; d = d,^d. = d^;b = id;r, = ^r;b, = ^r; ' b b, 10 100 ' 100 z°= Generally from 40° to 60°. Number of vanes, i.sr,, generally from 6 to 16. 30 HKATING AND VENTILATION. Example : — See Fig. 16. Required the volume of air delivered by a fan of the follow- ing dimensions : — Per cent, of effect, k ^ 25. d = 16 ft. ; r = 8 ft. ; r. = 5 ft. ; b = 1.25 ft. ; b, = 2.25 ft. z° = sin. 47° = 0.73. h = 0.025 ft; 1 ^ 10 ft. ; number of vanes 16 ; and n ^ 2 = 120 per minute. 0= •V/2X32. 166X0.025 X829 =: 36.6. 5 2.2c 36.6 , Cx = 5 X — 5 X -- = 56.4. 8 1.25 0.73 A = 16 X 1.25 X 3-1416 X 0.73= 4S-86- V = 2x45-86x56.4 = 5175. V, = 5175 ^ = 1293.75. Si7SX°-o2SX62.s Hp = ^—^ -^ ^ — 14-7. 55° Note : TJie seotional area of duct leading from the fan, sbould not be leu tlutn A. HEATING. GENERAL PRINCIPLES. Unit of heat : — Is a standard term for measuring the amount of heat absorbed or emitted during any operation ; in the United States and Great Britain, it is the amount of heat neces- sary to raise the temperature of i lb. of water i° Fahrenheit. Thus, to heat 50 lbs. of water 1° would require =50 x i = 50 units, or if it were required to heat 50 lbs. 20° it would be 50X 20X I = 1,000 units. Specific heat : — Is the capacity of a body for heat; it is the number of units of heat necessary to raise the temperature of the body, 1° Fahrenheit. See table. Transmission of heat : — I St. By radiation ; that is, the heated body giving out its heat in rays. 2d. By convection, the heat being conveyed from the heated body through flues. 3d. By conduction, the heat passing from a heated body to a colder one, when in contact. Loss of heat, or cooling of bodies, -^'Bo^ts are cooled : I St. By radiation. 2d. By contact, (with cold air. or a, colder body). 3d. By conduction. 32 Let T and T, t, t„ t, and t. HEATING AND VENTILATION. Temp, of air in room, see Fig. 17. Temp, of surfaces of walls. H, be the heated body. L, = Loss of heat by radiation. Lj = Loss of heat by contact. L3 = Loss of heat by conduction. Fig.l7 H will lose : ist. By radiation (L,), when T = T, = t^ = t3 > t = t, ; 2d. By contact (L,), when t = t, = t, = t, > T = T. ; 3d. By conduction (L3), when T, =t. = tj > T = t = tj 4th. By radiation, contact and conduction (L.+L^+Lj), when t3 > T = T. = t, = t = t,. Loss of heat by radiation : — Radiation is not affected by the form of the body, nor by the distance of the absorbing body; i' possesses the property of passing through moderate thick- ness of air or gases without heating them or losing any of its heat, to any appreciable extent. Air and gases can, under ordinary circumstances, be heated by contact only. Reference : — L, = Units of heat absorbed or emitted per square ft. per hour, by radiation. r = Factor for loss of heat by radiation, from experiments of Peclet. See table. HEATING. 33 t = Temp, in Fahr. of the radiating body, t. = Temp, in Fahr. of the absorbing body. L, = 22sr (1.0043'"^''— i-oo43"~^°)- For small differences between t and t, say 30°, when t, = 60° to 70°. L, := r (t — t,), will be sufficiently accurate for all practical purposes. VALUES OF r; Being the radiating and absorbing power of bodies, in units of heat per square ft., for a difference of 1° Fahrenheit, from the experiments of Peclet : Silver, silvered Copper 0.02657 Copper 0.03270 Tin 0.04395 Zinc and Brass, polished 0.04906 Iron, tinned 0.08585 " sheet 0.09200 " ordinary 0.56620 '' cast, new 0.64800 " sheet and cast, rusted 0.68680 Lead, sheet 0.13286 Glass 0.59480 Chalk 0.67860 Wood sawdust, fine 0.72150 Building stones. Plaster, Wood, Brick 0.73580 Sand, fine 0.74000 Calico 0.74610 Woolen stuffs 0.75220 Silk stuffs, Oil paint 0.75830 Paper 0.77060 Lampblack 0.81960 Water [.08530 Oil .' 1.48000 2* 34 HEATING AND VENTILATION. Loss of heat by contact with air: — The heat absorbed fiom a body by contact with cold air, is not influenced by the nature of the surface, all materials losing the same amount, under sim- ilar conditions of temperature ; nor does the form of the body affect the result materially, as was formerly supposed (see Gras- hof, " Theoretische Maschinenlehre," 1875); the loss varies only with the more or less disturbed condition of the air in contact, which is expressed by the factor y = 4, for quiet air, and for more rapidly moving air, as continually renewed air in room, y = S- Reference : — Lj = Loss of heat by contact, per sq. ft. per hour. t = Temperature of the heated body. T = Temperature of the air in contact (average). y = Factor = 4, for quiet air; = 5, for moving air. L, = o.09824y(t - If^^^' For small differences between t, and T, say 30°, when T = 60° to 70°, L^ = 0.09824 s(t — T) will be sufficiently accurate for all practical purposes. Loss of heat by conduction .-—A wall separates two rooms, A and B; A, having a temperature of 70°, and B, 40°, there will then be a certain amount of heat transmitted through the wall, from A to B ; the amount transmitted varying with the material of which the wall is built, and its thickness, for similar conditions of temperature of the surfaces. Reference : — Let L3 = Loss of heat by conduction per sq. ft. per hour. t = Temperature of heated surface, tj = Temperature of cold surface, e = Thickness of body between t and tj. c = Conducting power of the material, being the quanti- ty of heat transmitted, by a plate, i inch thick, the HEATING. 35 difference of temperature between the two surfaces, t — t, = 1° Fahrenheit, in units of heat, per square foot per hour. See table, page 37. Loss of heat through walls and wi7idows, per square foot per hour. Reference : — c = Conducting power of material, as per table, page 37. e = Thickness of wall or plate, in inches, r = Radiating power of the material, see table, page 33. Ij = Loss by contact of air, for a difference of 1°, see L=,page 34. q = r + U. T =: Temperature of internal air (in room). T, = Temperature of external air. T, = Temperature of internal air in adjoining room, t = Temperature of internal surface of wall, t, = Temperature of external surface of wall. t, and tj = Temperature of surfaces of wall, next to adjoining room, tj = Temperature of glass in windows, etc. U = Total units of heat lost per hour, per sq. ft. W = Walls or windows. Loss of heat through floors : — When the floor is exposed to the external air, the loss of heat will be by conduction only, and the formulas for loss of heat ihrough walls will apply, but when not so exposed this loss will be null. Loss of heat through ceilings ; — When the ceiling is compos- ed of brick arches, concrete, or joists lathed and plastered, and covered by a roof, the loss will be null ; but when the roof forms the ceiling, and is either of brick, concrete, slate, tin, glass, etc., 36 HEATING AND VENTILATION. the loss will be considerable by conduction, the same formulas applying as for walls, etc. Loss of heat through walls and windows : — When all sides of the building are exposed, Fig. i8. t = q(el,T+cT.)+l,cT. t. = c(2l,+r)+el,q ' ct+qeT. c+qe ' U = l.(T-t)=:^^')=q(t-T,) _ q(t-T.) __ I.cq(T-T,) . e c(2l,+r)+el,q i+q When one side only of the building is exposed, Fig. 19. "' "' When t, = T, t = t,- U q /T-T, ' '^q ' U^ (i^-^.) _ c(t-t,) . e e i+q- ForwallW,, t3 = "i^i-A^t, ; T, = li^+t3. Loss of heat through glass (windows, etc.) : — ^Windows, etc., of thin glass, not more than }£ inch thick. When T = t = t„ When T> t„ t = T+T. u = q(T-g. (T-t)U _ q -t+T. U=UT-tJ+r(t-t,). HEATING. 37 When all sides are glass (conservatories), When T>t, (l,T)+(l,+r)T. t4 = 2l,+r ; U=l.(T-g. CONDUCTING POWER OF MATERIALS. Value c, being the units of heat transmitted per hour per square foot of a plate i inch thick, the two surfaces differing in temp. i°. Copper 515 Iron 233 Zinc 225 Lead 113 Marble, gray, fine grained 28 Marble, white, coarse grained 22.400 Stone, calcareous, fine, 16.700 " " ordi- nary 13.680 Glass 6.600 Brick-work, baked clay 4.830 Plaster, ordinary 3.860 Oak, perpendicular to fibres 1.700 Walnut, perpendicular to fibres 0.830 Pine, perpendicular to fibres 0.748 c = Pine, parallel to fibres . . 1.370 Walnut, parallel to fibres . 1.400 Gutta percha 1-380 India rubber i-37o Brick dust, sifted i-33o Coke, pulverized 1.290 Cork 1-150 Chalk, in powder 0.869 Charcoal of wood, pow- dered 0.636 Straw, chopped 0-563 Coal, small sifted 0.547 Wood ashes 0.531 Mahogany dust 0.523 Canvas of hemp, new ..0.418 Calico, new 0.402 Writing paper, white . . - 0.346 Cotton, or sheep's wool. 0.323 Eiderdown °-3i4 Blotting paper, gray 0.274 For double windows, when the glass is not less than 2 inches apart, c = 3.6. Stagnant air, c = 0.3. 38 HEATING AND VENTILATION. UNITS OF HEAT EMITTED OR ABSORBED PER SQUARE FOOT PER HOUR. VALUES OF (t - -T) 1-233 := VALUES OF 1.0043' -3=. Whent — T= (t- -T)- 233 = When t or ti= i.oo43'-3== 10° 17.10 40° 1-034 20 40.19 5° 1.079 30 66.20 60 1.126 40 94-52 70 I-I7S 5° 124.40 80 1.226 60 155-76 90 1.280 70 188.36 100 1-336 80 222.08 no 1-394 90 256.79 120 1-455 100 292.42 130 1.518 no 328.88 140 1.584 120 366.13 15° 1-653 130 404.21 160 1-725 140 442-77 170 1.800 150 482.08 180 1.878 160 522.01 190 1.960 170 562.53 200 2.046 180 603.61 210 2-135 190 645.21 220 2.240 200 687.34 230 2-338 210 729-95 240 2.441 220 774-83 250 2.548 230 816.61 260 2-659 ... 270 2.776 ... 280 2.898 ■- 290 3-025 300 3-158 See X.J and L^, pages 33 and 34. HEATING. 39 Loss of heat by the incoming fresh air : — In ventilated rooms, where a certain amount of fresh air is suppHed, and impure air displaced, the heat necessary to raise the fresh air to a given temperature in the room, equals a certain loss per hour. Reference : — Let U = Units of heat necessary to warm the fresh air. T= Temperature of the internal air, generally 70°. T, = Temperature of the external air, see table. Q = Cubic contents of room, in feet. n = Number of times that Q is to be renewed per hour, w = Weight of a cubic foot of air, at the temp, of T,. s = Specific heat of air, see table, page 42. U = Qnws (T - T,). HOT WATER PIPES. Heated body of cast iron, r = 0.648. UNITS OF HEAT, U, EMITTED OR ABSORBED, PER SQUARE FOOT PER HOUR. -:|- ■3 UNITS or HEAl PER SQUARE POOT PER HOUR. tH By contact, By radiation and contact com- ill H % L 2= bined, L,-^L2. a g By radiation, Si B " ,y-3. . y=5.' .>'=3.. . y=5.' iS « air quiet. air moving. ^i ~ air quiet. air moving. 70 70 80 it 5-04 8.40 7-43 12.47 15-83 90 t( 11.84 19-73 15-31 27-15 35-04 100 it 19-53 32-55 23-47 43.00 56-02 no li 27.86 46.43 31-93 59-79 78.36 120 It 36.66 61.10 40.82 77-48 101.92 130 it 45-9° 76.50 50.00 95-90 126.50 140 tt 55-51 92.52 59-63 115.14 152-15 ISO tt 65-45 109.18 69.69 135-14 178.87 160 (( 75.68 126.13 80.19 155-87 206.32 170 It S6.18 143-30 91.12 177-30 234.42 180 tt 96-93 16I-SS 102.50 199-43 264.05 190 tt 107.90 179-83 114-45 222.35 294.28 200 tt 119.13 198-55 127.00 246.13 325-55 210 tt i3°-49 217.48 139.96 270.49 357-48 40 HEATING AND VENTILATION. Lf t — 32 ti — 32. \ . = 2251(^1.0043 —1.0043 ) L, = o.o9824y(t-T)'''''' Units of heat u„ emitted per lineal foot of pipe per hour. Let d ^ Diameter of pipe in ft. u, = ud3.i4i6. STEAM PIPES. Heated body of cast iron, r = 0.648. TTNITS OF HEAT, U, EMITTED OR ABSORBED, PER SQUARE FOOT PER HOUR *^'& ^ 'i UNITS OF HEAT PER SQUARE FOOT PER HOUR. s» By contact, By radiation and contact com- g-o" r- .0 L bined, L,iLj= "a» e a By radiation. €i^ I.S-S. a '3 .y=3' . y=s. L.= y=5. . y=5- S's i5 air quiet. air moving. air quiet. air moving. 210 7° 130.49 217.48 139.96 270.49 357-48 220 142.20 237.00 155-27 297.47 392.27 230 153-95 256.58 169.56 323-51 426.14 240 165.90 279.83 184-58 350-48 464.41 250 178.00 296.66 200.18 378.18 496.84 260 189.90 316.50 214.36 404.26 530-86 270 202.70 337-83 233-42 436.12 571-25 280 215-30 358-85 251.21 466.51 610.06 290 228.5s 380.91 267.73 496.28 648.64 300 240.85 401.41 279.12 519-97 680.53 Examples : — See table, page 38. Let t =210°; t. = T = 7o''; r = 0.648, and 7=3. L, = 225X0.648(2.135 - 1. 175) = 139.96. L, = 0.09824X3X442-77 = i3°-49- HEATING. 41 Units of heat required, per sq. ft. per hour, of heating surface, to heat i cubic foot of air, at different temperatures. Reference : — T = Temperature of air in room. T, = Temperature of external air. s = Specific heat of air = 0.238. w = Weight of a cubic ft. of air at T,. Uj = Units of heat required, per sq. ft. of heating surface per hour, u = Units of heat per sq. ft. of surface, per table, p. 39 40. u,= ws(T-TO; q = -^- q = Cubic ft. of air heated from T, to T, per sq. ft. of heating surface. - E Temperature of air in room, T = If 40= so- 60° 70° 80° 90" 100° 110° 120' 130° U2 := us = Us = U3 => u» = Uz = u,= Uj = Uj,= Ua = 0° 0.822 1.028 1-234 1-4.39 1.645 1.851 2.056 2.262 2.467 2.673 lO" 0.604 0.805 1.007 1.208 1.409 1.611 1.812 2.013 2.215 2.416 20° 0.393 O.S90 0.787 0.984 1.181 i-37« 1-575 1.771 1.908 2.165 S0» 0.192 0.38 s 0.578 0.770 0.963 1-155 1-345 1.128 1.540 1-733 1.925 40" 0.000 0.188 0.37b 0.564 0.752 0.940 1.316 1.504 1.692 ■;o° 0.000 0.000 0.184 0.367 0.551 0-735 0.918 1.102 1.286 1.470 60° 0.000 0.000 0.000 0.179 0..359 o-5.3« 0.718 0.897 1.077 1.256 70° 0.000 0.000 0.000 0.000 0.175 0.350 0.525 0.700 0.875 1.049 Example : — How many cubic feet of air, moving, will a square foot of cast iron pipe heat, by contact alone, the temperature of pipe being 160°, the external air 40°, and required temperature of room 70°? By table, u = 126.13, ^'^^ "= = °■^^^'> u 126.13 hence, 2»# ^ = u = 0.564 : 223.6 cubic ft. (the answer). 42 HEATING AND VENTILATION. SPECIFIC HEAT OF SOLID, LIQUID, AND GASEOUS BODIES. Number of units of heat necessary to heat one pound of the body i" Fahr. Iron, wrought o.i 138 " cast 0.1298 Copper 0.0951 Tin 0-0569 Zinc 0.095s Brass 0.0939 Lead 0.0314 Mercury 0.0333 Gold 0.0324 Silver 0.0570 Platina 0.0324 Bismuth 0.0308 Glass 0.1977 Marble, white 0.2158 Chalk, white 0.2148 Burnt Clay, white . 0.1850 Coal 0.2777 Sulphur 0.2026 Spermaceti 0.3200 Wood, pine 0.6500 Wood, birch 0.4800 Beeswax o-45oo Ice 0.5040 Water i.oooo Olive oil 0.3096 Alcohol 0.6220 Oil of Turpentine 0.4720 Gases under a constant pressure of 30 inches mercury. Oxygen 0.2182 Hydrogen 3.4046 Nitrogen 0.2440 Carbonic Acid 0.2164 Sulphuretted Hydro- gen 0.2423 Vapor of water 0.4750 Air 0.2380 WEIGHT AND VOLUME OF WATER OF DIFFERENT TEMPERATURES. Reference : — V — Volume of water of temp. T, that at 39° being unit. T = Temperature of water. w = Weight of a cubic ft. of temp. T. W = Weight of a cubic ft. at 39° V = i + (T-39)' 2009000 [o.23+o.ooo7(T— 39)] ' W HEATING. 43 WKIGHT AND VOLUME OF WATER OF DIFFERENT TEMPERATURES, r 1 V 1 w T V w 32 1. 000109 62.387 125 1.012743 61.603 35 1.000035 62.386 130 1. 014098 61.521 39 1. 000000 62.38805s 13s 1-015505 61.435 40 1.000002 62.388 140 1. 016962 61-347 45 1.000077 62.383 145 1.018468 61.257 5° 1.000254 62.372 15° 1. 020021 61.163 55 1. 000531 62.355 15s 1. 021619 61.068 60 1. 000901 62.332 160 1.023262 60.970 65 1. 001362 62.303 165 1.024947 60.869 70 1. 001909 62.269 170 1.026672 60.767 75 1.002539 62.230 175 1.028438 60.662 80 1.003249 62.186 180 1.030242 60.556 85 1.004035 62.137 185 1.032083 60.449 90 1.004894 62.084 190 1.033960 60.339 95 1.005825 62.027 195 1-035873 60.227 too 1.006822 61.965 200 1.037819 60.114 '°S 1,007965 61.899 205 1.039798 60.000 no 1.009032 61.829 210 1.041809 59.884 115 1.010197 61.758 212 1.042622 59-838 120 1.011442 61.682 ... VOLUME AND WEIGHT OF DRY AIR. At different temperatures, under a constant atmospheric pres- sure of 29.92 inches in the barometer, the volume of 32° being unit. Dry air expands or contracts uniformly 0.0020825 ^'^s volume per degree Fahr. in difference of temperature. Reference : — (Contents in cubic ft. and lbs.) V = Volume at temp. T. V = Volume at temp. t. v = '{^+.l^-. 480 (V-i) 44 HEATING AND VENTILATION. W= Weight per cubic ft. at 33° = 0.0807. w = Weight per cubic ft. at T. W Example : — V = 20 cubic ft. of air at 40° = t, is to be heated to 80° = T ; what is the volume V ? V = 20 > — I- I I = 21.660 cubic ft. (the answer). I 4.80 ^ / ^ Note- — In the following table V= i, and t= 32". VOUTME AND WEIGHT OF DRY AIR. T V w T V w °-93S 0.0864 27s r-49S 0.0540 12 0.960 0.0842 300 1.546 0.0522 22 0.980 0.0824 325 1-597 0.0506 32 1. 000 0.0807 35° 1.648 0.0490 42 1.020 0.0791 375 1.689 0.0477 52 1. 041 0.0776 400 1-75° 0.0461 62 1. 061 0.0761 450 1.852 0.0436 72 1.083 0.0747 500 1-954 0.0413 82 1. 102 °-°733 55° 2.056 0.0384 92 1. 122 0.0720 600 2.150 0.0376 102 1-143 0.0707 650 2.260 0-0357 112 1. 163 0.0694 700 2.362 0.0338 122 1.184 0.0682 800 2.566 0-0315 132 1.204 0.0671 goo 2.770 0.0292 142 1.224 0.0659 1000 2.974 0.0268 152 1.24s 0.0649 IIOO 3-177 0.0254 162 1.265 0.0638 1200 3-381 0.0239 172 1.425 0.0628 1500 3-993 0.0202 182 1.306 0.0618 1800 4.605 0.0175 192 1.326 0.0609 2000 5.012 0.0161 202 1-347 0.0600 2200 5.420 0.0149 212 1-367 0.0591 2500 6.032 0.0133 230 1.404 °-°57S 2800 6.644 0.0121 250 1.444 °-0SS9 3000 7-051 0.0114 HEATING. 45 HEATING WITH HOT WATER. GENERAL PRINCIPLES. In a hot water apparatus, the temperature of the water in the boiler never exceeds 212°, the mean temperature in the heating pipes being from 150 to 200°; the temperature in pipes is increased or dimiinished by stop cocks, for controlling the velocity or volume of water passing through the pipes in a giv- en time. Air vents or cocks must be provided, as water evolves air when its temperature rises to the boiling point. The air col- lects at the highest points of the apparatus, and at places where the horizontal flow pipe dips, and where the risers in the re- turn pipe connect with the horizontal, for instance at points a, in Fig. 20. The higher the ascending and descending pipes, or the greater the difference between their temperature, the more rapid will be the circulation. To increase the difference of temperature between the as- cending and descending pipes, either increase the quantity of pipe, so that the water will flow a greater distance, or decrease the diameter, so that they will part with more heat. The specific gravity in pipe li (Fig. 21), must be greater than in pipe h„ to produce circulation ; the greater amount of cooling should 46 HEATING AND VENTILATION. Flow pipe Heturicpipe Fig.21 take place in the coils above the dotted line aj or bottom of boiler. (See Fig. 21.) The hot water should rise to the highest point in the most direct way, so that the pipes give out the heat in returning to the boiler ; otherwise a reversal of the circula- tion might occur. All closed boilers must be pro- vided with a supply cistern, located above the highest point of the ap- paratus; it should be proportioned to contain about -^ of the whole quantity of water in the pipes and boiler. The pressure in the boiler and pipes increases only with the height of cistern above the boiler or lowest pipe. The pipe from cistern should lead to the bottom of boiler, or into the return pipe, and bent in the shape of a syphon, see Fig. 20, to prevent the escape of heat or vapor from the boiler. The effect is the same, whether there are more flow than return-pipes, or vice versa ; each range will act separately, hav- ing a velocity of circulation peculiar to itself; they may return to the boiler separately, or united in a main pipe. Horizontal leading pipes should be larger in proportion to the branch pipes than vertical leading pipes, because the flow of hot water is more rapid in vertical than in horizontal pipes. Vertical leading pipes, running through several stories, should decrease in diameter as they ascend, or be supplied with cocks to equalize the flow ; the hot water tending to rise to the highest, leaving the pipes in lower stories comparatively cold. When coils are somewhat distant from each other, the con- necting pipe should be smaller than the pipes in coils. Pipes must be kept scrupulously clean and free from shavings, dirt, etc., or circulation will be retarded. HEATING. 47 Expansion and contraction in the pipes must be provided for. The advantages of hot water over steam are : less cost of fuel ; no danger of explosion ; requires less repairs ; the temperature in pipes is maintained 6 to 8 times longer than in steam pipes, after the fire is extinguished; and another great advantage is, fhat the temperature in the pipes can be increased or dimished, by reducing the flow of the hot water. DIAMETER OF PIPES — BORE. Connection Pipes to Coils. UPPER STORY OF A Bun.DING, DIRECT RADIATION. COIL SURFACE. DIAM. OF PIPS. SECTIONAL AREA. 6o sq. ft. or less. ^ [ inch. 0.44 sq. inch. 100 " ii I (C 0.78 175 " n I^ ' " 1.22 " 250 « ii I^ \ ." 1.76 -600 " ii 2 it 3-14 For each successive lower story, increase tlie cross sectional area of pipe by 15% over that in the preceding story. BASEMENT OR CELLAR OP A BUILDING, INDIRECT RADIATIOK. The sectional area of a branch pipe must equal the area of all the connections, and the area of a main pipe must equal the area of all branches. 48 HEATING AND VENTILATION. The return-pipes to a coil or series of coils must have the f^-me diameter as the respective flow-pipes; for example see Fig. 22. Fig.22 Reference : — Fig. 22. a = Flow connection pipes, i in. diam. b = Return connection pipes, 1 in. diam. c = Flow branch pipe, i^ in. diam. d = Return brancK pipe, i^ in. diam. e := Flow main pipe, 2 in. diam. f — Return main pipe, 2 in. diam. g = Coils. Fijies in Coils. — The diameter of pipes in coils should be : When coil is in contact with the incoming air, which is in- tended to be warmed, the diameter should not be less than 2j^ inches ; when the coil is a direct radiator, not in contact with cold air, die diameter should not be less than 1 1^ inch. FLOW OF HOT WATER IN PIPES. The circulation of water in pipes of a hot water apparatus is caused by the difference in weight of two columns of water, connected at top and bottom, see Fig. 23 ; one column being HEATING. 49 continually heated, and the water expanded, thereby produc- ing a difference in weight, and in consequence a circulation. The velocity increases with the temperature in the rising column, and the loss of temperature in the return column ; it is reduced by the friction in the pipes and elbows. The friction in pipes decreases with the velocity, and, in a less degree, with the increase in diameter of the jiipes; it also de- creases with the temperature of the water, up to certain limits ; this, however, is not considered in the following : Let Fig. 23 represent a boiler with main circulating pipes. Reference : — (All dimensions in ft. and lbs.) See Fig. 23. Let H = Effective head of water, producing motion. Hi = Height of water above lowest point of return pipe. t =Temp. of water in boiler = 210°. t, = Temp, of water as it returns to boiler. . . t+t, t^ = Average temp, of water m pipes = —^ ■ T = Temp, of air in contact with pipes, w = Weight of water at the temp. t. w. = Weight of water at the temp. t,. Q = Quantity of water to be moved, per second. 3 50 HEATINP AND VENTILATION. q = Contents of one lineal foot of pipe, u, = Units of heat given out by the pipe per lineal foot, per hour. 1 = Ixngth of pipe. A = Sectional area of pipe, d = Diameter of pipe, f = Friction in straight run of pipe, f, = Friction in elbows. V = Velocity of water in pipe in ft. per second, g = Accelerated gravity = 32.166 ft. per second, u = Units of heat given out per sq. ft. per hour, as per table, page 39. n = Number of elbows. Wj = Weight of water at temp, t^ H. W ( , r , rM V° „ H H = H.-^={x + nf. + f^}ll; H.= w w. ^i+nf,+f 1 A ^d° ■ "> d= qw4t,-T)' Q= V = o.78s4d°v; 4 u, = ud3.i4i6; q = 0.7854 d=; A = o.78s4d'; t, = 2t,-t ; 0.017152 f B O.OI439H — j=^ Vv HEATING. 61 FRICTION IN ELBOWS OR CONNECTIONS, I. XL. IV. YI. f.= 1.968. 84,{!r d a = — 2 When r = 2a, f^ =0.294. When r = loa, f. =0.131. 'Fig.29 J > 52 VII. HEATING AND VENTILATION. f, = 2{ O.I3I + I.847(-^)^}; d a = — . VALUES OF fi, FOR ELBOWS V AND VI. When - = O.I 0.2 0-3 0.4 0-5 f. = 0-131 0.138 0.158 0.206 0.294 when - = 0.6 0.7 0.8 0.9 I.O f. = 0.440 0.661 0.977 1.408 1.978 Coefficient of Friction, f, for Given Velocities, v. -S3 > o. O.OI 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 o. 10 O.I I 0.12 0.13 0,14 0.15 0.16 0.17 0.18 0.1859 °-i356 0-1133 O.IOOI 0.0893 0.0843 0.0790 0.0750 0.0715 0.0685 0.0660 0.0638 0.0624 0.0601 0.0586 0-0585 0.0556 0-0547 10.19 I 0.20 ! 0.21 0.22 0.23 0.24 0.25 0.26 0.27 0.28 0.29 0.30 0.31 0.32 0-33 0-34 0-3S 0.36 0-0536 0.0526 0.0517 0.0508 0.0500 0.0493 0.0486 0.0479 0.0473 0.0467 0.0461 0.0456 0.0451 0.0446 0.0442 ] 0.0437 0.0432 0.0428 0.37 0.38 0-39 0.40 0.41 0.42 0-43 0-44 0-4S 0.46 0.47 0.48 0-49 0.50 o-SS 0.60 0.65 0.70 0.0425 0.0421 0.0417 0.0414 0.0410 0.0406 0.0404 0.0401 0.0398 0-0395 0.0393 0.0390 0.0388 0.0385 0.0374 0.0364 0-0355 0.0348 0-7S 0.80 0.85 0.90 0-9S 1. 00 1. 10 1.20 1.30 1.40 1.50 1.60 1.70 1.80 1.90 2.00 0.0340 0-0334 0.0329 0.0323 0.0318 0.0314 0.0306 0.0299 0.0293 0.0287 0.0283 0.0279 0.0274 0,0271 0.0267 0.0264 f =0.01439 + 0.017152 HEATING. 53 Examples : — A pipe 500 ft. long, 4 in. = 0.33 ft. diameter, shall have an average temperature t^ = 150°, the temperature of air and walls surrounding it to =70°; what is the velocity v, head H, and column H, ? 1 = 500. d = 0.33. u, as per table = 178.87. 1 = 210°; T = 7o''. w„ at the temp, t^ = 61.2. u. = ud3.i4i6 = 178.87x0.33X3. 1416 = 185.44 units per hour per lineal ft. of pipe. q = o.7854d' = 0.7854X0.33° = 0.088 cubic ft. u,l 185.44x500 _ 92720 ~ qWj(t, — T) "~ 0.088x61.2(150 — 70) ~ 430.85 = 21 1^.2 ft. per hour = ^ = 0.06 per second. '' ^ 3600 ^ {, 1 I v° ( „ 500 ) 0.06' 0.0036 ^ = 128.73 -7^-^ =0.0072 ft. 64.33 t, = 2t^— 1=2X150— 210 = 300—210 = 90°; and w„ for 90° = 62.05; w, for 210°= 59.83. H 0.0072 0.0072 . , H = = ^- = -r = 0.2 = 2.4 mches, w 59.83 0.036 w, 62.05 54 HEATING AND VENTILATION. DIMENSIONS OF BOILERS, GRATES, ETC. Reference : — A = Total area of heating surface of boiler, in square feet. A, = Area of grate, in square feet. a = Area of boiler, directly heated, in square feet, a, = Area of boiler, indirectly heated (flues), in square feet. a, = Sectional area of boUer. aj = Sectional area of flues (all), D = Diameter of boiler. d = Diameter of flue. 1 = Length of boiler or flues. n = Number of flues in boiler. K = Number of pounds of coal consumed per hour. U = Total units of heat given out by the coils or radiators, per hour. u = Units of heat given out by i lb. = 6000 (effective). ^-6^' K = U of coal, generally DI3.I416 a=- u D dln3.i4i6; a2 a. d = a==+'i-3 2.s; a. In3a4i6' 1 = a, = a, 0.4 a. dn3.i4i6 dl3.i4i6 The flues in boiler are generally 2 to 4 inches diameter; the sizes used varying with the length of boiler or flue, and the quality of coal designed to be used, as follows : LENGTH OF BOILER, DIAMETER OF FLUES, IN INCHES. IN FEET. Soft i-oal. Hard coal. 8 or less 10 12 16 2 ^% 3 4 2 2 2>^ 3 Distance between flues, or .shell and flue, i to i^ inch. HEATING. 55 Example : — A hall, Fig. 7, 100 feet long, 80 feet wide, and 40 feet high, the surrounding walls 20 inches thick ; the ceiling flat, covered by a hipped roof; the two opposite sides of the hall are pro- vided with windows, 8 to each side, 4 feet wide and 14 feet high. The hall to be heated by indirect radiation, located in the basement, under the hall floor. The heating apparatus to be a "hot water," the temperature in pipes not to exceed 160°; the boiler to be a " cylindrical flue" boiler. The hall to be occupied by 300 persons, for twelve hours each day, the vitiation not to exceed 0.06%. Ventilation to be the vacuum movement, by means of air as- pirating chimney; the currents in hall to be upward and not to exceed 1.5 ft. per second. Loss of Heat per Hour. All sides of the building exposed, walls of brick j see for- mulas, page 36. ^^ l.cq(T-T.) c(2l, + r)-|-el,q 0.4912 X 4-83 X 1.227(70 — 40) ~ 4.83(2X0.4912 + 0.7358) + 20 X 0.4912 X 1.227 2.911X 30 87-33 ~ 4.83(0.9824 -f 0.7358) -f 12.054 8.299 + 12.054 z°-3S3 ^ \ = 0.09824x5X1 = 0.4912. c = 4.83. q = r -f 1, = 0.7358 = 0,4912 = 1.227. r = 0.7358. e = 20 inches. T = 70°. T, = 40'. 56 HEATING AND VENTILATION. Windo'ftfs y^ in. thick glass ; see formulas, page 36. U = q(T-tJ = 1.086(70-55) = 16.29 per sq. ft. \- 2 - 2 -55- r = 0.5948. q = r + Ij = 0.5948 + 0.4912 = 1.086. Incoming fresh air ; see formulas, page 39. U = Qnws (T - T.) = Vws(T - T,) = 1032000X0.079X0.238(70 — 40) ^582109.92. Q = 100x80X40 = 320000. V = 16x215x300 = 1032000, or 3440 cubic feet for each occupant, per hour. V 1032000 n =p^= = 3.2. Q 320000 s = 0.238. w, at^4o° = 0.079 ^'^^• Total Loss of Seat. From walls. Area, (100 + 10° + 80 + 80)40 — 896 = 13504 ; U = 13504X4-29 = 57932.16 From windows. Area, 14X4X 16 = 896; u = 896 X 16.29 = 14595-84. From incoming fresh air. For 300 occupants 582109.92. Total 654637.92 HEATING. 57 Heating Surface S. For indirect radiation, when the temjDeratare of radiator shall not exceed 160°, i square foot of hot water pipe, for airinov- ing, gives 126.13 units per hour. Number of square ft. of heating surface = •: -— = 5190, or lineal ft. of 4 in. diam. pipe= — ;; — , = 4956- ^^ 126.13x0.33x3.1416 320000 Cubic fL of au:lieated, per sq.ft. of surface = -i^ = 61.6. 5190 Size of Boiler. ^^ 654637-9^ ^ 6 sq.ft. 600 Quaniity of Coal Consumed ^er Hour, for Boiler. 1L^^ = 654637:92 _ ,^^ ^^^^ 6000 6000 Area of Grate Surface. K 109.10 „ A, = — — — - — = 10.91 sq. ft. 10 10 ' Size of Openings in Floor and Ceiling. 1032000 Velocity of current, 1.5 ft. per second ; total area .— 1.5X3600 = 154 sq, ft, or 154 openings i ft. square. Aspiratiiig Chimney. Assumed velocity of air in shaft = 10 feet per second. Height of chimney, 80 feet. 58 HEATING AND VENTILATION. ,, . , , V IO'^200O bechonal area = A = — - — = — '^ = 28.7, or a square V3000 36000 = -v/z8.7 = 5.3s, say 5.4 feet. The temperature necessary in the shaft to produce a velocity of 10 ft. is, v=(i + et)(i + f 1 + f.) (t, — t) ; in which ' 2ghe t = 4o°; t, = 70; e = 0.00208; g = 32.166; 1 = 200 ft. ; h = 80 ft. ; f = 0.05, and f, for 4 square elbows = 1.5X4 = 6.0 ; d = 5.4. Hence \o\\ + 0.00208X40) (1 + 0.05 1-6) ^ _^ 5'4- __ Ihrfl __ An\ ^~ 2X32.166X80X0.00208 ^ ' 100 X 1.0832x8.81; q;8.63 = ^ ^ — 30 = ^ 5 — 30 = 8q — 30 10.72 "^ 10.72 ^ ^ o = S9'- Quantity of coal necessary to produce this temperature, ^^ t,sW 59x0.238x81528 K= -^-irr = — =^ ^ — = 211 lbs. per hour. u% 5400 If the plenum movement were adopted,, using a Rittinger fan, the horse-power required would be, with the ^ of effect at 30, Hp = 0.38 Vh = °-3gX 1032000x0.14 ^ 549^2^ ^ 3600 3600 ->■ ' and allowing 8 lbs. of coal per horse-power, which is ampls, K = 15.2x8 = 121.6 lbs. per hour. HEATING. 59 HEATING WITH STEAM. GENERAL PRINCIPLES. In heating with steam, the pipes forming radiators, are gene- rally smaller in diameter than those for hot water, the tempera- ture increasing with the pressure of steam in the boiler. The temperature in pipes should never be below 212°; other- wise the steam rapidly condenses to water, to get rid of which the pipes must be inclined so that the v/ater may easily flow back to the boiler, or drip pipes communicating with the bottom of radiators and feed pipe ; the pipes should be so inclined, that the water will flow in the same direction that the steam does. The steam leaves the boiler at the top, and the water from the condensed steam returns at the bottom. The fire under the boiler must be kept brisk, or the heating effect ceases rapidly. A cock should be placed between the boUer and heating pipes, on opening which the steam drives the air in the pipes before it, to an outlet or air cock that must be provided at the end of the pipe and at the bottom of radiators. It is sometimes necessary to resort to air pumps for extracting the air in the pipes, especially when the coils are on different levels. The boiler should be so proportioned, that it will evaporate as much water as is condensed in the pipes ; and supplied with water by a stone float valve, the cistern being sufficiently high above the boiler that the pressure of water will overcome the pressure of steam in the boiler ; when practicable, force pumps or injectors are used, these appliances require no elevated tank or cistern. The boiler must be supplied with safety valves, steam gauges, water gauges, and also gauge cocks, to indicate the pressure of steam and height of water. A blow-off cock, at the bottom of (50 HEATING AND VENTILATION. boiler, is also required, for supplying and cleaning the boiler every week or so, depending on the quality of the feed water. Steam possesses an advantage over hot water, in the ease of application, where great inequalities and frequent alterations of level occur, and particularly where the boiler must be placed higher than the places to be heated. For buildings occupied at intervals, steam is more effective than hot water, in its rapid generation of heat ; so also for buildings using power boilers, when of sufficient size to supply both engine and radiators. The original cost of steam apparatus is somewhat less than hot water apparatus. Expansion and contraction in the pipes must be provided for. The apparatus must receive constant care and attention, the fire must be kept brisk, the water at the proper level, and the steam not allowed to generate too fast, endangering perhaps the safety of the boilers. DIAMETER OF PIPES — BORE. AVhai pressure of steam is not above 15 lbs. per sq. inch (saturated steam). Connection Pipes to Coils — Direct or Lidirect Radiation. COIL SURFACE DIAM OF PIPE. SECTIONAL AREA. 25 sq . ft or less. ?i inch. 0.44 sq. inch. 40 (£ it I it. 0.78 <( 80 <£ a ^u " 1.22 (t 160 ii u ^H u 1-76 ie 250 ii 2 3-14 le Flow Pipes. The sectional area of a branch pipe must equal the area of all connection pipes, and the sectional area of a main pipe must equal the area of all branch pipes. HEAriNG. 61 Return Pipes. The sectional area of the return pipes from a coil, or series of coils, must be one size less than the respective flow pipe to the coils. Drip pipes should connect with all risers (vertical flow pipes), the water being taken into the return pipes or boiler. The sectional area of main pipes should be reduced as soon as practicable. Coils. Diameter of pipes in coils, from ^ to 2 inches. DIMENSIONS OF BOILERS, FURNACES, AND FITTINGS. Area of Fire Grate. With chimney draught = 0.1 to 0.04 sq. ft., per lb. of fuel per hour. With fan or blast = 0.04 to 0.0 1 sq. ft., per lb. of fuel per hour. Sectional Area of Flues or Tubes. From T to J area of grate. Capacity of Boiler. Steam and water space = heating surface X from 3 to i^ foot, in cylindrical and flue boilers ; and from i to 0.5 foot, in tubular boilers; and about o.i foot, in water-tube boilers. Capacity of Furnace, Tubes, and Flues From 6 to 8 ft. X area of grate. Area of Safety Valves in Square Inches. The greatest weight of water to be actually evaporated in lbs, per hour x Q.006. 62 HEATING AND VENTILATION. Steam and Water Space. Steam space = 0.4 total space. Water " =0.6 " Water should stand not less than 4in. above heating flues. The evaporating power of boiler should be 30% larger than the quantity of water condensed in the pipes. The temperature of steam in pipes diminishes with the dis- tance from the boiler. The horse power of a boiler is equal to the number of cubic feet of water evaporated per hour. When steam above 15 lbs. pressure is used, the boiler should be provided with a steam drum or dome = Yz steam space given above, so that the steam space = 0.525 total space. Reference : — A = Total area of heating surface of boiler, in square feet. A, = Area of grate in square feet, a = Area of boiler, directly heated, in square feet, a, = Area of boiler, indirectly heated (flues), in square feet, a, ^ Sectional area of boiler, aj = Sectional area of flues (all). D = Diameter of boiler, d = Diameter of flue. 1 = Length of boiler or flue, n = Number of flues in boiler. K =: Number of pounds of coal consumed, per hour. U = Total units of heat given out by coils or radiators, per hour, u = Units of heat given out by i lb. of coal (effective). 6; = Units of evaporation = 966 units of heat required to evaporate i lb. of water, under one atmosphere. Wi = Total quantity of water, condensed in pipes, coils, etc., in lbs., per hour, w, = Pounds of water at 212°, evaporated by i lb. of fuel. Hp = Horse power of boiler. HEATING. 63 A = J A, = O.I K to 0.04K for chimney draught ; DI3.1416 ,, a= ; a, = dln3.i4i6j a, = a3S.o; aj^a^o.a; r, ^2 a. a. 13.1416' hi3.i4i6' nd3.i4i6 ' a. n = dl3.i4i6 ' U u • W W e/ ' e.' w ' C2.5 Note. — The same proportions of flues and distances between them, given for hot water boilers, ^pply £^so to steam boilers. TEMPERATURE OF STEAM IN BOILER, AND PRES- SURE PER SQUARE INCH. Reference : — I = Inches of mercury that balance the steam. P = Pressure of steam per square inch in boiler, in lbs. T = Temperature of steam in boiler, t = Mean temperature of steam in pipes. I = ■{ 785+°-S8407 ) = P 2-0376 ; P= (—+0.52} "=10.48875; ( 202 ' T= I VP— 0.52 I 202; t = — T. Note.— These formulas are approximate only, but agiee ^te well with actual lo •nlt9' See table, page €4. 64 HEATING AND VENTILATION. PEESSHEK PER SQUARE INCH IN BOILER, P= OF STEAM IN PIPES, OF STEAM IN BOILER, Pressure of Atmosphere, 14.73. t = T = Included. Excluded. 210° 221.0° 17.67 2.94 220 231-5 21.38 6.65 230 242.0 25-75 11.02 240 256-5 32.89 18.16 250 263.0 36.58 21.85 260 273-5 43-31 28.58 270 284.0 51.04 36.31 280 295.0 60.25 45-52 290 305-0 69.77 55-04 300 315-0 80.98 66.25 Example : — Required, the dimensions of steam boiler, quantity of pipe, etc., to heat the hall, as per example, page 55. External temp., = 40°. Temp, of pipes, mean 230°. Temp, of hall = 70°. 20 Temp, of boiler = — 230 = 242°.!. Total pressure in boiler for 242° = 26 lbs. per square inch, in round numbers. Total units of beat to be supplied to hall= 654637.92 per hour. Units of beat per square foot of pipe, per hour, by contact for indirect radiation ^ 256.58. , .. 6c46'^7.Q2 Number of square feet of pipe = ''^ , ' ^ =2551.4. lineal ft of 2 in. diam. pipe = — 77— r~ 7. = 4892. ^^ '' '■ 0.166x3.1416 320000 Cubic ft. of air heated per sq. ft. of suriace = = 125. 2551.4 HEATING Size of Boiler. 6000 , ^^ 677.6 -6.2; K = -^= 109.3; 65 •~ 966 ' 6.2 A, = 0.1 X 109.3 = 10.9, 3«* * 66 HEATING AND VENTILATION. COMBUSTION OF FUEL, Combustion consists in the rapid combination of substances with oxygen, generally carbon and hydrogen, the result being the development of heat and light. The following are the principal combustibles used in the arts, and their chemical composition, according to Pdclet : Sign, Coal. Cole. Woofl. Substance. Terfrrtly dry. ■ Ordmary suae. Charcoal. Carbon c n o N W A 0.812 0.048 0.054 0.031 o-°5S 0,850 0.150 0.510 0-053 0.417 0.020 0.408 0.042 °-334 0.200 0.016 0.930 Hvdrocren Oxvffen ----- Nitrogen and Sulphur Water Ashes 0.070 Total 1. 000 1,000 1,000 1. 000 1. 000 The following substances consist of :- C, I lb. of Carbonic Acid consists of : 0.2727 lbs. of carbon. Water Air C.+2O. 2O1 ^-q-^^ = 0.7273 " oxygen, H. 0,+ H. O, O.+H. O. 2N,+0. 2N. 2N.+or = 0.111 " hydrogen, = 0.889 " oxygen, =: 0.222 " oxygen. = 0.778 " nitrogen. HEATINO. 67 In which the chemical equivalents are :— of C, = 75.00; H, = 12.50; N, = 175.00; O, = 100.00. To estimate the theoretical units of heat in lb. of fitcl : — Distinguish the constituents into carbon, hydrogen, oxygen, and refuse, as per table, page (>(>. The quantity of each being in fractions of a lb. analyzed. U = 14500 C + 62000 I H — — > • Net weight of air chemically necessary for the complete com- bustio7i of a unit of weight of fuel, theoretically : — Reference : — W = Lbs. of air required, w = Weight of a cubic ft. of air. V = Volume in cubic ft. W=i2C + 36(h-^); W v = — . In most cases, additional air is required to sufficiently dilute the products of combustion, the increase being in the ratio of I JS^ to I, or 2 to I, of the theoretical value. 68 HEATING AND VENTILATION, LFFICIENCY OF FURNACES AND BOILERS, APPROX. Reference : — A3 = Intended number of square feet of heating surface (meaning both direct and indirect), per lb. of fuel per hour. E = Efficiency of furnace or boiler. U := Theoretical units of heat in a lb. of fuel. U, = Effective units of heat in a lb. of fuel. U. = UE. When the draught is produced by a chimney : — T- A, II A3 +0.5 12 When the draught is produced by a fan or blast .'— . T- A, II A3 +0.3 12 EXAMPLES OF EFFICIENCY (U — 13000). A3 E U, Small heating surface 0.50 0.46 5980 '' °-7S 0-S5 715° Ordinary heating surface in tubular boilers 1. 00 0.61 7930 1.25 0.65 8450 1.50 0.69 8970 (. 2.00 0.73 9490 Water tube and cellular ( 3.00 0.79 10270 boilers ) 6.00 0.84 10920 The efficiency is liable to be diminished from 0.2 to 0.5 of its proper value, through unskillful firing. HEATING. 69 PROPORTION OF SMOKE CHIMNEYS. Reference : — A = Sectional area in square ft. V = Volume of smoke delivered in cubic ft. K = Pounds of coal consumed per hour. h = Height of chimney in ft. V = Velocity of smoke in ft., per second. t = External temperature, average 50°. t, = Internal temperature, average 550°. v = o.o8v'(t. — t)h; v/(t.-t)h' V = Av = Ao.o8-/(t. -t)h; t. - 1 1 A ) Generally, allowing 600 cubic ft. of smoke for i lb. of coal, K ( K ) » A = 0.128 —T^, and h = 0.01638 ^ -r- { • HYGROMETRY. HUMIDITY OF AIR. Air, in a free or normal state, contains more or less vapor oi water. When this air is passed into rooms, over heated bodies and its temperature is raised, the quantity of moisturfe it con- tains is not diminished, but the relative humidity is lessened; or, in other words, its capacity for containing moisture is increased. When the air is cold, it may contain very little vapor, and yet be moist ; and on the contrary, when it is warm, it may contain a considerable quantity of vapor, and be very dry. In summer, there is usually more aqueous vapor in the air than in winter, yet it is less moist, the air being farther from its point of saturation, by reason of the higher temperature. The degree or point of saturation, or hygrometric state, is the ratio of the quantity of aqueous vapor, actually present in the air, to that which it would contain were it saturated, the tem- perature being the same. A body, gradually cooling in the ambient air to a lower tem- perature, will in time be at a temperature when the vapor in the air, being condensed, will be precipitated on the surface of the body in the form of dew; this temperature is called the dew point. To determine the humidity of air, Wet and Dry Bulb Hy- grometers are used, the dew point being obtained by noting the temperatures of the wet and dry bulbs, and inserting the values in certain formulas, given below. The methods generally used to hydrate or moisten the aii in rooms to the desired ratio or percentage of saturation, are : KYGROMEtRY. 71 by placing shallow vessels, containing water, in the hot air ducts, the evaporation being increased by the application of heat to the vessel ; or copper cylinders, placed horizontally and transversely across the duct, heated internally with steam or hot water, vapor being formed by the evaporation of drops or jets of water falling on the top of the cylinder ; or, for summer, sprays of cold water ejected through small holes in a pipe or series of pipes ; in each case the air passes through, and takes up a cer- tain amount of vapor, the quantity being regulated by adjust- ing the flow of water or temperature of the heat producing eva- poration. Reference : — T = Temperature of air. t = Temperature of the diw point, t, = Temperature of the wet bulb, tj = Temperature of the dry bulb. I = Height of barometer, balancing the air ( = 30 inches generally). Ij = Height of barometer, balancing the dry air (of the mix- ture.) p = Elastic force of vapor at the temperature T, in inches of mercury, p, = Elastic force of vapor at the temperature t, in inches of mercury. W = Weight of the vapor, in lbs., in a cubic foot of dry air mixed with vapor, w = Weight of a cubic foot of dry air, in lbs., at the tempera- ture T. w = Weight of the dry air, in lbs., in a cubic foot of saturated air. w, = Weight of the vapor, in lbs., in a cubic foot of saturated air. w = Weight of the air and vapor, in lbs., in a cubic foot of saturated air. 72 HEATING AND VENTILATION. w, = Weight of vapor in i lb. of air. Wj = Weight of dry air in lbs., mixed with i lb. of vapor. R = Ratio of humidity to saturation. wl, ,/WP , w, = -j^; w, = f^-y-; W3 = w,+w,; w, = — ; W5 = — ; W = w,R ; * w, ^ w, I.=I-p; R = |"; p=|; p. = pR; t = t,-(t,-t.)k; 0.0807 29.92 490.4 VALUES OF k. TEMPERATURE OF DRY k TEMPERATURE OF DRY k TEMPEILATURE OF DRY k BULB. BULB. BULB. Below 24° 8..S From 31 - 32° 3-7 From S5°- 60° 1.9 From 24°- 25° 6.9 32-33 3-3 " 60 - 65 1.8 " 25-26 6.,S 33-34 3-0 " 65 - 70 1-7 " 26-27 6.1 34-35 2.8 " 70-75 1-7 •' 27-28 S-b 35-40 2-5 " 75-80 1.6 " 28-29 .S-i 40-45 2.2 " 80-85 1.6 " 29 - 3° 4.6 45-50 2.1 " 85 - 90 i-S " 30-31 4.1 50-55 2.0 HYGROMETRY. 73 ELASTIC FORCE OP VAPOR OF WATER IN INCHES OF MERCURY, AND WEIGHT OF DRV AIR PER CUBIC FOOT, IN LBS. p = 29.92 at 212°. •s i' •s fa 1- of a cubic dry air, DS. |i •)S2 W e S.H ¥ ¥ ■S(i! H u< ^ H u* ^ h Ui i T" p w T° p w T p w 0.044 0.0864 31 0.174 o.oSog 63 0.576 0.0758 I 0.046 0.0861 32 0.I8I 0.0807 64 0.596 0.0757 2 0.048 0.0860 33 0.188 0.0805 65 0.617 0.0756 3 0.050 0.0858 34 0.196 0.0804 66 0.639 0.0754 4 0.052 0.0855 35 0.204 0.0802 67 0.661 0.0752 5 0.054 0.0853 36 0.212 0.0801 68 0.685 0.0751 6 0.057 0.0852 37 0.220 0.0799 69 0.708 0.0750 7 0.060 0.0850 38 0.229 0.0797 70 0-733 0.0748 8 0.062 0.0848 39 0.238 0.0796 71 0-759 0.0747 9 0.065 0.0846 40 0.247 0.0794 72 0-785 0.0746 10 0.068 0.0845 41 0.257 0.0793 73 0.812 0.0745 II 0.071 0.0843 42 0.267 0.0791 74 0.840 0.0743 12 0.074 0.0842 43 0.277 0.0789 75 0.868 0.0742 13 0.078 : 0.0840 44 0.288 0.0788 76 0.897 0.0741 14 0.082 0.0838 45 0.299 0.0786 77 0.927 0.0739 15 0.086 0.0837 46 0.3II 0.0784 78 0.958 0.0738 16 o.ogo 0.0835 47 0.323 0.0783 79 0.990 0.0736 17 0.094 0.0833 48 °-33S 0.0781 80 1.023 0-0735 18 0.098 0.0831 49 0.348 0.0780 81 1-057 0-0734 19 0.103 0.0830 5° 0.361 0.0780 82 1.092 0-0733 20 0.108 0.0828 51 0-374 0.0776 83 1. 128 0.0731 21 0.113 0.0826 52 0.388 0.0775 84 1.165 0.0730 22 0.118 0.0824 53 0.403 0-0773 8S 1.203 0.0728 23 0.123 0.0822 54 0.418 0.0772 86 1.242 0.0727 24 0.129 0.0821 55 0-433 0.0771 87 1.282 0.0725 25 0-I3S 0.0819 56 0.449 0.0769 88 1-323 0.0724 26 0.141 0.0817 57 0.465 0,0767 89 1.366 0.0723 27 0.147 0.0816 58 0.482 0.0766 90 1. 40 1 0.0722 28 0-153 0.0814 59 0.500 0.0765 91 1-455 0.0721 29 0.160 0.0813 60 0.518 0.0763 92 1. 501 0.0720 30 0.167 0.0812 61 0-537 0.0762 93 1.548 0.0719 62 ' C.556 1 0.0761 i •■ 74 HEATING AND VENTILATION. Example : — The temperature of the air in a room is 70° ; the temperature of the wet bulb is 60°. Required the temperature of the dew point, the weight of vapor in a cubic ft. of air, and the degree of humidity. Given : T = 70°, t. = 60'. t, = 70°. I = 30"- p for 70° = 0.733 inches, w for 70° = 0.0745. Requii-ed (the answer) : t°=S3°- w, = 0.0011377 lbs. R ^ 0.55. W = 4.38 grains. I, = 29.267 inches, w, = 0.0726 lbs. w^ = 0.0156 lbs. Wj = 65.09 lbs. t = t,-(t,-t.)k = 7o-(7o-6o)i.7 = 53° ; ,/ wp . 0.0741; X 0.731: w, = ^ X ^ = s/aX '^^ ^ '-^^ =0.0011377; w,, in grains = 0.0011377x7000 = 7.96 grains; p., for 53° = 0.403; p, 0.403 „ ^^. P 0-733 W = w,R = 7.96x0.55 = 4.38 grains J I. = 3°— 0-733 = 29.267 ; 0.0745x29.267 w. 3° w, 0.00113 ; 0.0726 ; Wj 0.0726 w, 0.0726797 Wj, 0.0011377 = 0.0156; = 65.09 ; HYGROMETRY. 75 EVAPORATION. Wlien moisture must be supplied to the air of ventilated rooms, by the methods just explained, the following formulas give the quantity of water to be evaporated per hour, required for the desired humidity ; the superficial area of the water ; and the units of heat necessary to produce the evaporation of the water of a given temperature, in a given temperature of the am- bient air. Additional Reference: — A = Area of water surface in sq. feet, exposed to the air. E = Water evaporated, per sq. ft. of surface, in lbs., per hour. H = Units of heat required to raise i lb. of water from o° to tj, and then evaporate it. 11, = Units of heat lost by radiation from the water, per sq. ft., per hour. See formulas, page 39. Hj = Units of heat lost by the air which carries off the vapor from the surface of the water. K = Pounds of coal required to evaporate the water. R, = The desired per cent, of humidity, generally 70. s = Specific heat of air = 0.238. tj = Temperature of the. water to be evaporated. U = Units of heat required to evaporate i lb. of water. U, = Units of heat required to evaporate W3 lbs. of water, u = Units of heat in i lb. of coal ; generally 6000. W = Weight of water in lbs. in i cubic foot of air before hydration. W, = Weight of water in i cubic foot of air, the humidity of . which = R, in lbs. W, = Weight of water to be evaporated for i cubic ft. of air (from R% to R,% of humidity). Wj = Total weight of water to be evaporated per hour. 76 HEATING AND VENTILATION. C = Cubic ft. of air, per hour, to be hydrated. z =: Time in hours necessary to evaporate i lb. of water at the temperature t^. Water Below the Boiling Point H = 1081.4 + 0-305 tj ; H,= 225r^_i.oo43^ — 1.0043 i ' H,= W3s(t3-T); U=H + H.+ H,; E = (p— p,), for quiet air (no ventilation) ; E = - T (P~P') » fo*" ^^ moving; I ^=E' W = w,R; W. = w,R,; W, = W. -W; W3:=W,C; w u Heating surface, see u, and A,, pages 77 and 78. ' U. (t,-t3) ' A. u. t4 = ^Tr+t3- Example : — Continued from page 74. A hall is to be supplied with 3,000,000 cubic feet of air, at a temperature of 70°, per hour. Water at 180°. Wj = 0.0011377 lbs. W = 0.000625735 lt>s. R, = 0.70, when saturation = i.oo. t3 = 180. 1 = 30. HYGROMETRY. 77 I, = 30—15-3 = 14-7 inches, for i8o°. Temperature of the dew point := 53°. p, = 0.403 inches, for 53°. u = 6000. w = 0.062 lbs., for tj. p = 15.3 inches, for 180°. w I, 0.062X14.7 I _ 30 _ 0.03038 _ — *.-53j ' -/'*^P ,/0.o62XiS.3 0.01976 y^-T ^' ^ — E = ^^^|^(iS-3-°-403) J = 2.76; ^ = ^ = «-36 '^°"'"SJ H= io8i.4+(o.30sXi8o) = 1 136.3 J H, = 225x1.0853(1.878—1.175)0.36 = 62.14; H» = 1.53X0.238(180—70) =40.1 ; U = 1136.3 + 62.14 + 40-1 = 1238.5 ; W3 ^0.000170655x3000000 = 512; U. =512x1238.5=634112; W, = o.ooi 1377 X 0.70 = 0.00079639 : W, ^0.00079639 — 0.000625735 =0.000170655; „ 634II2 6000 -^ ' Water at the Boiling Point. t3=2I2°. Additional Reference : — A, = Superficial area of the heated surface in contact with the boiling water, in sq. ft. t^ = Temperature of the surface A^ (t^ > t^). 78 HEATING AND VENTILATION. II, = Units of heat per square foot, per hour, emitted by sur- face A,. Values ofM^: — u, = For vertical tubes passing through the water 230 For a double bottomed or steam-cased vessel 330 I'or horizontal tubes, or worm 430 H= io8i.4+(o.3osX2i2°) = 1146.06; . = 225r(i.oo43 3 _ 1.0043 )z ; Hj = o, for boiling water; U = H + H.; U,(t, — 2I2)A,_ W,= A.= 966 966 W3 u,(t,— 212)' 966 W, Example : — How many pounds of water are evaporated per hour by an open vessel, with a 2 in. diam. pipe passing horizontally through the boihng water, having 20 superficial feet of heating surface, and filled with steam at 260° ? u,(t.— 2i2)A, 430(260—212)20 „ W, = ^' rr = ^^-^ T-r — ^ — = 427-3 Ibs. per hour. 3 966 966 The evaporation at the boiling point is the most effective and economical. VENTILATION. VACUUM SYSTEM.— Steam Jet, Fig. 31. Steam jets are sometimes applied in the ventilating shaft, at what point is immaterial as to effect ; the steam acting as the motive power, by creating a partial vacuum for the air from below to fill, as also impelling the air out of the shaft, similar to blast- pipes of locomotives for increas- ing the draught through smoke pipe. The percentage of effect of the stem jet is about — - of the ■^ 100 amount of coal consumed. Diameter of blast pipe, gene- rally }4 inch. The effectiveness is increased by widening the shaft towards the top. Reference : — G = Volume of air, in lbs., passing out of the shaft, per second. S = Volume of steam, in lbs., passing out of the blast pipe, pei second. A = Area of blast pipe outlet. A, = Area of shaft or chimney. Aj = Total area of all air or smoke ducts leading to shaft. X = Pressure of atmosphere over pressure in chimney or shaft. h = Pressure of steam in boiler, h, = Pressure of atmosphere — 33.95. Fig.3l Measured by column of water = 33.95 ft. 80 HEATING AND VENTILATION. p = Pressure of steam in boiler, in lbs., per sq. inch. a = Coefficient of friction in outlet of blast pipe = 1.663. u = — = Sum of coefficients of friction in ducts leading to JD shaft; for values of which see f, page 81. In locomotives, u = 6 ; B = ■^. k: G ~ S" A. A = m; K A~ n; h _P 33-95 14.7 X ~ m^ a(m — a(m ■ -i)h -1)4 G ■Bn'^' S ■ ; m = i+ Vi + Bn'j h=(m— i) _ /n'( m— i) V u m^+ n Additional Reference ; e = Density of the steam emitted by the blast pipe, (water e, = Density of the air = 800, for water = i. g = Accelerated gravity = 32.166. V = Velocity of efflux of steam, in ft., per second. V, = Velocity of air in shaft. C = Cubic ft. of steam emitted per second. W = Weight of steam emitted per second, in lbs. VV; = Weight of air emitted per second, in lbs. C, = Cubic ft. of water to be evaporated by boiler per hour. v= •v/2ghe; C = vAf; )2.5xC e C3600 W = ^ifl^;W. = Wkj K = Amount of coal consumed per hour. w = Pounds of water, at 212°, evaporated by i lb. of fuel. VENTILATION. 81 Hp = Horse power of boiler. Hp = C.; K = ^i^5. Coefficient of Friction, f : — f = 0.56, orifice in a thin plate, f = 0.75, short cylindrical pipe. f = 0.98, short cylindrical pipe, enlarged outward, trumpet shaped. Example : — Let p = 5 lbs. per square inch, in boiler. u = Sum of coefficients of friction in ducts and shaft = 6, e = 1250, for steam at five lbs. pressure, when water = i. A — 0.00136 square ft. A, =^ 4.0 square ft. Aj = 5.0 square ft. w = 8 lbs. water evaporated, per lb. of fuel. A, 4.00 A» c.oo , , h = 33:95iiS^„ 14.7 ^^' X = 1.663(2941 — 1)11.54 _ 56421.6 294i'-i.663(294i-i) + g3676 ^^^"^ '""^ = 0.009 ^^^^ > G _ / 3676°(294i-i) _ / 397281494 40 _ — S ■V6X3q4i=+.-?676 V 5iQOoq62 " v76S4 4 6X3941"+ 3676 V 51900562 27.6 times more air than steam, in units of weight ; 82 HEATING AND VENTILATION. v= Vzxsz.ieex 11.54x1250=: ■/928003.52 = 963.3 ft. per second ; C ^ vAf =: 963.3 X 0.00136x0.75 = 0.982 ; „, 62.5x0.982 „ W = — ^ =! — = 0.0491 lbs : 1250 1.3CC W, = 0.0491x27.6 = 1.355; ^°^ ^i"" of 7°° temp. =- — -- = 18 cubic ft. of air per second, being a velocity of v. = -- = 4.5ft.; 4 ^^^0.982x3600^^3 1250 , K = — — 5 — ^ =22 lbs. of coal per hour. 8 Computing the velocity of the air in shaft from the pressure, x. ,, v'2gxe, ■v/2X 32.166x0.009x800 ^463. 176 v, would = fr — = ,— = — — vu v6 2.44 2 I. C2 = — -^ = 8.82 : consequently the per cent, of effecf 2.44 4. c = =-- = 0.51, or for velocity of 8.8, o.o u v,= , , m=— a(m^-i)+Bn=x hi4.7 X = and h = —, '-^ : p = — ^^-L. 2ge. a(m-i) ^ 33.95 HEATING. FLOW OF STEAM IN PIPES. The pressure and temperature of steam in a pipe decrease H'ith the length of the pipe and the heat lost per unit of time. The loss of pressure in the pipe, caused by friction and the loss of heat, does not affect the question of Heatitig and Ven- tilation ; but the decrease of the temperature of the steam in the pipe, caused by friction, must be known to compute the amount of heat lost or emitted ; and to compute the temperature we must know the pressure. The following formulas give the diminished pressure at the end of long pipes, when the initial pressure in the boiler, and the quantity of water evaporated per hour, are given. Reference : — V = Volume of steam in cubic ft., of the pressure P, from I cubic foot of water. v = Velocity of the steam in the pipe, in feet, per second. C = Number of cubic feet of water evaporated in the boiler, per hour. P = Pressure of steam in the boiler, in lbs., per square inch. P, — Pressure of steam in the pipe, in lbs., per square inch, at the distance 1 from the boiler. 1 = Length of the pipe in feet, or distance from the boiler where P, is required, d = Diameter of the pipe in inches, a = Sectional area of the pipe in feet, f = Coefficient of friction. See page 52. h = Head of steam for velocity v, in feet. 84 HEATING AND VENTILATION. h, = Vertical distance in feet from the boiler to the highest or lowest point that the pipe rises or falls, g = Accelerated gravity = 32.166. m = Specific volume of the steam. = ■/2gh ; h = --; m = ^— -. 3600a ^ S ' 2g' 62.5 When the pipe rises from the boiler, When the pipe falls from the boiler, p. = p|i-=j-!— (fl£ih-h.)}. For straight pipe without elbows, r °-2I7 - f = — J-!-, same as for air ; see page 23. Vv Example : — A boiler evaporates 20 cubic ft. of water into steam of 45 lbs. pressure ]3er square inch, per hour ; the steam is passed through a pipe, 300 feet long and 2 inches in diameter. What are the velocity of the steam in the pipe and the pressure at the end of the pipe ? 562X20 3.1222 V ^ 3600 0.0218 = 143.2 J f = 0.018; a ^ = 13^:766 = 3^«-7^ '" = 6^^=9.0; ^M 45X144X9^ 2 •* ''i I 10325.88 ) , ^ = ^5 {^--^3-1^; = 45 (I -0.177) & 37.035 lbs. per square inch. ADDENDA. LOSS OF HEAT THROUGH WALLS. All sides of the room exposed (no surrounding rooms), formula, page 36. l.cq(T-T,) . c(2l, + r) + el,q' Brick Walls. T-T. = 1°. 1, = 0.09824 X 5 = 0.4912, see page 35. c = 4.83, see page 37. r = 0-7358, see page 33. q = r + 1, = 0-7358 + 0.4912 = 1.2.27. ^^ 0.49I2X4-83X 1-227x1 ■~ 4.83(2X0.4912 + 0.7358) + ex 0.4912 X 1.227 2. 911 "8.299+6X0.6 Stone Walls. T— T, = 1°. \ = 0.4912. c = 22.4, for coarse marble, being about an average. r = 0.7358. q = 1.227. 0.4912 X 2 2.4 X 1.227 X ^ 22.4(2X0.4192 + 0.7358) + eXo.49i2X 1.277 ^ 13-5 "^ 38.487 + ex 0.6 86 HEATING AND VENTILATION. TABLE BASED ON THE FOREGOING FORMULA. Thickness, e, of wall. Loss in units of heat, U, per square foot per hour, for a difference of z° between the external and internal air. in inches. Brick. Stone. 4 0.273 0.330 8 0.223 0.312 12 0.188 0.295 i6 0.163 0.280 20 0.144 0.267 24 0.129 0-2S5 28 O.I16 0.244 32 0.106 0.234 36 0.097 0.224 40 o.ogo 0.216 LOSS OF HEAT THROUGH GLASS (Windows). Case I. When the air in a room and the internal surfaces of walls have the same temperature, T = t = t^, U = q(T-tJ; and for a difference between the external and internal tern- T+ T perature of 1°, when t^ = ^ = J^, U = 1.086 X J^ =^ 0.543, per square foot per hour. Note:— q =:r+lj; r = 0.5948; 1, = 0.4912. ADDENDA. 87 Case II. When the air in a room is of a higher temperature than sur- face of wall opposite to window in question, U = 0.45, per square foot per hour, on an average. Case III. When all sides of the room are glass, as in conservatories, and temperature of internal air higher than temperature of in- ternal surface of glass, U = 0.3s, per square foot per hour, on an average. NOTES. Fresh air inlet openings should be somewhat larger than the exit openings. The temperature of air in occupied rooms, heated, should be about 70", to which the heating apparatus must be proportioned, when untler fall working power, in heating the external air from its lowest known range ; see table of " Minimum and Mean Temperature." In indirect radiation, the top of coil must not be higher than the bottom of heating or hot air flue ; while in direct radiation, the bottom of coil must not be lower than the top of fresh air inlet opening. The smokestack from boilers is generally placed in aspirat- ing chimney, and its heat utilized in rarefying the air in it. BOILERS. By Total Heating surface of a boiler is understood all that superficial area of the boiler in contact with flames and hot gases from the fire in the furnace — that is, for cylindrical tubular boilers, the lower half of the shell and the whole of all the tubes. By Effective Heating surface is understood a certain mean between that part of a surface receiving the greatest, and that 88 HEATING AND VENTILATION. part receiving the least amount of heat generated in the fur- nace — it is the whole of a horizontal surface over a fire or hot gas ; one half of a vertical surface in contact with a fire or hot gas ; three fourths of the lower half of shell exposed to the fire, and half of the area of all tubes or iiues heated internally. On an average it is from A to |- of the total heating surface. For example : — A cylindrical tubular steam boiler, 4 feet in diameter, 15 feet long, and containing 49 tubes, 3 inches in dia- meter, has a total heating surface of half of the area of shell in addition to the area in the flues, equal to 94 feet in shell (not counting the ends) and 577 feet iji flues, total 671 square feet. The effective heating surface of this boiler is : ^ of 94 ft., and ^ of 671 ft., or a total of 406 square feet. The heat utilized per square foot of total heating surface, is for:— Steam boilers, from 1200 to 3600 ) units of heat per Hot water boilers, from 600 to 1800 J sq. ft. per hour. On an average, 15 square feet of effective, or 25 square feet of total heating surface, are required per horsepower, the effi- ciency increasing with tlie size of the boiler. A cubic foot of water, evaporated (from 60° to 212°) per hour, is equal to one horsepower, nominal. The following formula is used to compute the effective heating surface for steam boilers. Let A = Total effective heating surface of boiler, and Hp = Horsepower: A = [Hp-f(VHpX2.s)]x8. Steam boilers for heating purposes are generally proportioned with a greater total heating surface per cubic foot of water evaporated, than those used for power only. A Hot water boiler requires about twice as much total heating surface as a steam boiler for the same amount of work in units of heat. It requires about 11 18 units of heat to raise the temperature of I lb. of water from 60° to 212° and evaporate it ; therefore, i horsepower will require, 1118x62.5 = 69875, say 70000, units. ADDENDA. 89 pasrei oq 01 -(10131 rKM„mooi^i^nooocovoooooui»«i * (Ads 05 UJ CC 1? d .a —1 m « H ^^ w < f^ 1 o B "^ o CO 'g ' "IS I ■an a ■ §-" S ■ "a I •gS.1 •pasitri aq oj -duiai ui m m moo •som m m m 12 SI i5 !1 2.^ !2°^ ^0 trS.'^'^o O O ONcomfor-^mo o •psjinbai s; 911} -som JO -ojij t^^O p^co r^ ts ro [<« t» t^oo ts 0^0*0 mco o ^*^^^«.co^o ^mt^m* ■U!W UT!3J^ lITJSpy ■ujM ■il]Vi •"IN M\noo ■* H T M M MM 1 1 ' 'I? TCOfOlO'^fOfOC) I N N O NO ooo^ooo -If o\ti M mo ^n-ro\ t^oo co "O »>. ■> -•'—■■ CI M m I " ' V I ro M C^^O ^ T^ P>. H H o\ N O "1 O^C0 00 00 0\ -J- tN tHO ^ I- I r» « m^ H ^ g vo o ^ O t^oo i « tnwoo O w 'J- ^00 o ( ^ o* « CO M moo fo o « ^ o^ ^ 00 ro m c^ o rooo h w o -^oo »n o\ o ^^ ^ « Mill I iiTT I I I I (HOt^'*Hro«M m ij- H ts.00 o ■* « m m t^ ro«3 oo «> i> "} K>f3 fiSlS^S S?Sm?mS> Mm« MM wmfOfON H mvo M rT*« mroroN w ■>)-'^r co m fo lo^ o I I I ro m^ o MD h* I I n "T ro moo 00 O O O M m^q ^ "^ « V^ '^^^ S* T* S" MM 7T T"ii| £«^ • c.B J>> H G ;d M o pq > > Wall. r Window, r, ■1^ Cubic space, c 1 8 Wall, r to Window, r, Cubic space, c 1 Wall. r \b Window. ri ^ Cubic space, c O^ 9^ Or Wall, r Window, r. Cubic space, c E 00 Wall. r o Window, r, ^ Cubic space, c Wall, r 00 Window, r, 00 Cubic space, c w vb Wall. r b Window, ri w n H > > H O •z K Temperature of coil. Cubic space, c 1 % M a w w o i > 3 Wall, r 00 Window, r. 00 OS to Cubic space. c 1 Wall. r b Window, ri Cubic space, c 1 o OS so Wall. r Window. ri s Cubic space, c Oj sb Wall, r b Window, r. OJ Cubic space, c "o so bs Wall, r Window. ri so Cubic space. c » bs Wall. r SO Window, ri Is) o Cubic space, c ^ ON Wall. r Wifidow. ri fa M n H fd > O 1— 1 > H KH V O H a' •z (i> ^- y a •z o ■a ^ m p n s ^ ^ n a > r -I 3 iz; ^j H Li l-H M "T*' > „ > H n 3 ►t-i r\ 1— 1 O *%. > n -{ P 1 5 fd ft 1 n K l.'l > 2; 4 ^ H OS a n > !i •z n w Tl W ?d K c: fd 92 HEATING AND VENTILATION. SIZE OF PIPES TO AND FROM COILS. Reference: — R = Superficial area of heating surface in coils, in square ft. A == Sectional area of flow or return pipe, in square inches. D = Diameter of flow or return pipe, in inclies. h = Height of coil above bottom of boiler, in feet. A = R 0.009000 — 0.00025 h- Tj A 0-7854 D° j^ = r = r ; 0.009000 — 0.000025 " 0.009COO — 0.000025 '^ D = 1. 1284 v'R 0.009000 — 0.000025 h. The following table of diameter of pipes and coil surface they will supply are calculated from the above formulae. The table gives the sizes required in practice, wliich are ample for any size of apparatus, whether for a concentrated or extended system, with due allowance for friction and re- tardation from valves or other fittings. To find the required size of a pipe, whether flow or return, find the square feet of coil surface it must supply, under the height over boiler; the diameter will be found in first column on the same horizontal line. For Example: — A coil containing 153 square feet of heat- ing surface, 40 feet above bottom of boiler, requires a ij5^- inch-diameter pipe. ADDENDA. 93 Diameter of main and branch pipes and square feet of coil surface they will supply, in a low-pressure hot-water ap- paratus {212°) for direct or indirect radiation, when coils are at different altitudes for direct radiation or in the lower story for indirect radiation : u a c i- g-s DIRECT RADIATION. HEIGHl OF COIL ABOVE BOTTOM OF BOILER, IN FEET. S 10 20 30 40 5° 60 70 80 90 100 Sq. ft. Sq. ft. Sq.ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq.f. Sq.f. r^ 49 5° 52 S3 55 57 59 61 63 65 68 0.4417 I 87 89 92 95 98 loi 103 108 112 116 121 0.7854 1% 136 140 144 149 153 158 161 169 175 182 189 1.227 ij^ igo 202 209 214 222 228 235 243 252 261 271 1.767 z 349 359 370 380 393 405 413 433 449 465 483 3141 '% 546 577 595 613 633 643 678 701 727 755 4.908 3 78s 807 83s 856 888 912 041 974 1009 1046 1086 7.068 3'A 1069 1099 1132 1 166 1202 1 241 1283 1327 ■374 'i'J 1480 9.621 4 139s 1430 1478 1520 1571 1621 1654 1733 179s 1861 1933 12.56 ■t'A 1767 1817 1871 1927 1988 2052 2120 2193 2272 2356 2445 15.90 5 2185 2244 2309 2379 2454 2531 257.1 2713 2805 2907 3019 19.63 6 3140 3228 3341 3424 3552 3648 3763 3897 4036 4184 4344 28.27 7 4276 4396 4.^=8 4664 4808 4964 S132 5308 5496 5700 5920 38.48 8 5580 S744 5912 6080 6284 6484 6616 6932 7180 7441 7735 50.26 9 7068 7268 7484 7708 7952 8208 8482 8774 go8 9424 9780 63.62 10 8740 897S 9236 9516 9816 10124 10296 10852 1I2ZO 11628 12076 97-54 II I05S9 10860 11 180 11519 1 1879 12262 12666 13108 13576 14078 14620 95.03 12 12360 12912 13364 13696 1420S 14592 15052 15588 16144 16736 17376 113.09 13 14748 15169 15615 16090 16591 17126 17697 18307 18961 19633 20420 132-73 M 17104 17584 18109 18656 19232 19B56 20528 21232 219S4 228CO 23680 153-93 15 ■9«34 20195 20789 21419 22089 22801 23561 24373 25244 26179127168 176.71 16 22320 22978 23648 24320 25136 25936 26464 27728 28720 29776130928 201.06 HEATING WITH STEAM. Practical rules and tables for determining the dimensions of a gravity steam-heating apparatus, heating surface of boiler, its grate surface, radiating surface, and size of steam and return pipes. Reference :— A = Superficial area of external walls, exclusive of inside partitions, in feet. A, = Superficial area of windows, in feet. g^ HEATING AND VENTILATION. C = Cubic contents of space to be heated, in feet. H = Total heating surface of boiler, in square feet. G = " grate R = " radiating surface in heaters or coils, in sq. feet. (- ^ Cubic feet of space heated per square foot of radiator. r = Square feet of wall r = " '' window " * 1 HEATING AND GRATE SURFACE OF BOILER. For smaller buildings or private residences : — when R = 70 to 200 square feet: — H =— and G = — 5 25 when R = 200 to 500 square feet: — H=| andG= -. 6 30 For. public or larger buildings: — H = — and G = — . 7 35 RADIATING SURFACE IN COILS OR HEATERS. When rooms are exposed on all sides: — c r Tj when rooms are exposed to the northwest: — R = - + ^- + ^■ c 1. 15 r 1-15 rj when roonas are exposed to the southeast: — c 1.2 r 1.2 r. ADDENDA. 95 \^ Ul *-« Steam pressure, in lbs. per sq. inch. M 004^ Cubic space, c 1 \0 OO-vi Wall, r ^^ -f^ -1^ 00-1^ Window, r. ^-4 0^ On *J^ 6 Cubic space, c 1 % ^ 00 Wall, r is) bo-i^ Window, ri •M -vj o 00 W ON Cubic space, c 1 O^ ^ p ^o 4i>- (j^ ^ Wall. r b "^ b Window, ri -3 PI S "0 \0 COM M *^ Cubic space, c 33 > b ■-- ;-« Wall, r O ■n On On"-" ■^ to r > VI v>\ w Wall. r povj o " +. 00 Window, ri OJ to bo Cubic space. c to o vp M 3\ Wall. r ^0 \0 00 N i. Window, ri >^ to Cubic space. c \ N M M Wall. r M P O ■ijp l^ VJ Ln Wall. r n b ■ d Window. r. > > H O 0^ w ^ Cubic space. c 1 ? " P Wall. r 0^ *-" Window, r. ^ VO 00 On ^ J to (^ Cubic space, c 1 H < W H > -f^OJ to 4^ bO b Wall. r VI OS 0> »-n\0 to Window, ri M to " vj^ Cubic space. c 0^ > C P) 1) P) H 1—1 o 2; > ^^ b bo Wall, r co- w H n w w to to to VI vji to to .-. M 00 p\ oj b\ Wall. r p ^ 00 i.n 4^ ».n Window, ri OJ Oi to Ul vj v.n vj Cubic space, c M to to to ■{^ ." p "to to b Wall. r to " Window, r. 4^ 00 00 .-' OOUn OOW Cubic space. c \ OJ to to poi^ b '^ Wall, r 1^ ^Ui Window, ri i^ ^ n H !* > > H ^ 7; »' ^ ^ w n ►tJ ■^ n » a -I 3 *-t ^ 2; ii b r ^ ^ ?iJ ^ § Si ^ > ■« ^ " ?3 .0 =1 n ffi l.~J > ^ ^ w » n s- ^ « 2; n PI -d M ?d ffi d fd 96 HEATING AND VENTILATION. SIZE OF STEAM PIPES TO AND FROM RADIATORS. Reference:— R = Superficial area of radiating surface, in feet. D = Diameter of flow pipe to radiators, in inches, d == " of return " from " " P = Steam pressure, in lbs. per square inch. 1 = Distance in feet from boiler to radiators or branch, w ^= Weight of a cubic foot of steam at pressure P. / R D = =V '«4 = -l/"' R = -^- V'-^-- d = v^- The diameter of pipes and amount of radiating surface they will supply, given in the following tables for different boiler pressures, computed from the above formulae, allow for all sources of retardation from fittings, such as elbows, valves, etc. To determine the diameter of a supply branch pipe: — Find the area of radiators to be supplied, in the column of areas under distances from boiler; the dimension given in first column on the same horizontal line will be the required size. To determine the diameter of the main supply pipe: — In the column under distances from boiler, where a branch pipe is taken off, find the area of all radiators supplied from this point; the required size of pipe will be found in the first column on the same horizontal line. Example : — Steam pressure i lb., area of radiator 45 ft., 400 ft. from boiler, necessary pipe i inch diameter for branch pipe. Total area of radiators to be supplied, from this point say 1000 ft. Under column of distances for 400 ft. ADDENDA. 97 we find 1037, and the corresponding diameter of pipe in first column 3J^ inches. Diameter of sieam supply pipes and sq. ft. of radiating smface theywill furnish with steam from 9 to (>2'^ feet from boiler. STEAM PRESSURE i LB. PER SQUARE INCH. 215.50 Diameter of pipe, DISTANCE OF R.-IDIATOR FROM BOILER, IN FEET. in inches. 9 64 100 22s 32 1 400 484 625 Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. ■fi 146 55 44 29 24 22 20 17 I 301 113 90 60 50 41 41 36 Ik 529 198 I.:8 106 88 79 72 63 ^V9. 832 312 249 166 139 124 113 99 2 1707 640 512 341 284 256 233 205 2^ 2982 iiiB 894 596 497 447 406 357 3 4708 1765 I4I2 941 784 706 642 565 3^ 6919 2595 2075 1384 "53 1037 943 828 4 9146 3429 2743 1889 1524 1371 1247 1097 AV,. 12966 4862 3889 2593 2161 1944 1768 1555 5 17005 6377 5IOI 3401 2S34 2550 2319 2040 6 26628 9985 7988 5325 443S 3994 3631 3195 7 39150 14684 1 1 747 7831 6526 5873 5340 4608 8 54679 20504 16404 10936 9113 8202 7456 6560 9 73659 27622 22098 14731 12276 1 1049 10044 8836 10 95496 35811 28648 19099 15916 14324 13022 11459 STEAM PRESSURE 3 LBS. PER SQUARE INCH. 222°. Diameter of pipe, DISTANCE OF RADIATOR FROM BOILRR, I\ FEET. . in inches. 9 64 100 225 324 400 484 625 Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. y^ 240 90 72 48 40 36 32 29 I 494 185 148 98 82 74 68 59 ii4 863 324 259 172 144 129 118 103 ^y% 1361 510 408 272 226 204 185 163 2 2796 1049 839 559 466 419 3«i 335 2^ 4884 1831 1465 977 814 732 666 585 3 7700 2887 2310 1540 1283 "55 1050 924 31^ 1 1323 4246 3 97 2264 1887 1698 1544 1358 4 15819 5932 4745 3164 2636 2372 2157 1898 4j^ 21226 7959 6368 4245 3537 3184 2894 2547 5 27997 10361 8289 5599 4666 4144 3768 3315 6 44230 16586 13269 8846 7372 6634 6031 5307 7 64013 24005 19204 12802 10668 9602 8729 7681 8 89615 33605 26884 17923 14936 13442 12220 10754 9 120275 45103 36082 24055 20046 1 8041 16401 14433 10 156277 58604 46883 31255 26046 23441 21310 18753 98 HEATING AND VENTILATION. Diameter of steam supply pipes and sq. ft. of radiating surface they will furnish with steam from 9 to 62^1 feet from boiler. STEAM PRESSURE 5 LBS. PER SQUARE INCH. 227.5°. % 2 2K 3 3J^ 4 4i^ 5 6 7 8 9 10 DISTANCE or RADIATOR FROM BOU-ER, IN FEET. Sq. ft. 288 604 1058 1669 3434 5980 9436 13899 19430 25958 35133 53433 78439 109517 137053 191360 64 Sq. ft. no 224 397 626 1288 2242 3539 5212 7286 9734 13175 20037 29414 41068 55144 71760 Sq. ft. 88 181 317 500 1030 1794 2831 4170 5829 7787 10540 16030 25531 32855 44116 57408 Sq. ft. 59 121 211 334 686 1196 1887 2779 3886 5191 7026 10686 15687 21903 27410 38272 324. Sq. ft. 48 100 176 278 572 996 1572 2316 3271 4326 5855 8905 13076 18253 25642 31893 Sq. ft, 44 90 158 250 515 897 1415 2085 2914 3893 5270 8015 12765 16427 22058 28704 484 Sq. ft. 40 82 135 227 468 815 1290 1895 2649 3540 4791 72B6 1065 1 14934 20052 26094 625 Sq. ft. 35 72 127 200 412 717 1132 1667 2331 3114 4216 6412 11412 13142 17646 22963 STEAM PRESSURE 10 LBS. PER SQUARE INCH. 2400 Diameter DISTANCE OF RADIATOR F iOM BOILER, IN FEET. in inches. 9 6+ 100 225 324 400 484 62s Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. Sq. ft. ^ 366 137 109 73 61 55 50 44 I 752 282 225 150 125 112 102 90 ii4 1312 492 393 262 218 196 179 157 I '2 2074 777 622 415 345 311 281 249 2 4244 I59I 1273 848 707 636 578 509 2^. 7436 2788 2231 1487 1239 1115 IOI4 892 3 1 1 702 4388 3510 2340 1950 1755 1595 1404 3,1^ 17205 6452 5161 3441 2884 2580 2346 2064 4 24042 goi6 7212 4808 4007 3606 3278 2884 4^ 32292 1 2 109 9687 6458 5382 4843 4403 3873 5 42013 17505 12604 8402 7002 6302 5729 5040 6 67564 25337 20269 '3513 1 1 260 10134 9213 8107 7 97372 36514 29211 19474 16228 14605 13278 1 1 684 8 136209 51078 40862 27242 22701 20431 18574 16344 9 182955 68608 54886 36591 30492 27443 24948 21954 10 237973 89240 71392 47594 39662 35696 32451 28556 Ccitulogue of tht Scientific Piiblicatiom of D. Van Nostrand Company, 23 Murray Street and 27 Warren Street, New York. ADAMS, J. W. Sewers and Drains for Populous Dis tricts. Embracing Rules and Formulas for the dimensions and con struction of works of Sanitary Engineers. 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