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WARMING AND VENTILATION. 



WAKMINO AND VENTILATION. 



71J 



11 round. It stood in vessel of water. The hotter the stove, the 

 more the water evaporated, o as to keep the air in a proper hygro- 

 methc stata. The steam generated from this water also carried off the 

 heat from the iron quickly, and thua aided in warming the building. 



Warming by Steam. The employment of steam boilers in Urge esta- 

 blishment* where steam engine* are worked, i* one of the circumstance* 

 which have led to the very extensive adoption of the method of warm- 

 ing by (team. A marked difference is observable in the principle of 

 this method, as compared with that of hot-air warming. The heated 

 agent, that is, the steam, is not permitted to mingle with the air of the 

 room which is to be wanned, but acts through the medium of the 

 metallic tube which confines it, and which it raises to a temperature 

 sufficient to warm the room, without imparting a burnt quality to 

 the air. 



The general arrangements of a steam-heating apparatus, as suggested 

 by Mr. Scott Russell, are somewhat as follows : At a convenient part 

 of the building, and as low as possible, there is to be placed a close 

 steam-boiler of the ordinary construction. From this boiler a small 

 steam-pipe is to be carried to the part of the building which is to be 

 warmed. This small pipe should be pretty thick, and carefully rolled 

 round with a bandage of flannel to the thickness of a quarter of an 

 inch, and the boiler should be wholly covered with bricks and plastered 

 over to keep in the heat. This smaller steam-pipe should have an area 

 of one square inch for every six gallons of water that the boiler can 

 boil off in an hour. Pipes of a larger size are to be laid round the 

 room above the floor ; or under the floor, if apertures be left to allow 

 a free circulation of warmed air to enter the room. Into these larger 

 pipes the steam is to be conducted, and in them the steam will be con- 

 densed into water, giving out its heat to the colder air of the room 

 which is in contact with the outside of these pipes. Small leaden or 

 tin pipes must be provided, for the purpose of bringing back this 

 condensed water into the boiler, for which movement a gentle slope is 

 given to the pipes. The water thus returned, being again heated in 

 the boiler and converted into steam, is again made to ascend and give 

 out iu caloric to the room which is to be warmed. 



The efficacy of this mode of heating depends on the great capacity 

 for heat which steam possesses, a capacity equal to 1000 ; that is, a 

 pound of water at 212' will absorb a thousand degrees of heat in 

 becoming a pound of steam. Steam will thus communicate as much 

 heat as a mass of red-hot iron ; and it will have this advantage over 

 the iron, that it can carry this heat to a distance without a similar 

 loss, because the heat, being latent, will not be given out until it arrive 

 at its destination and become condensed, when the whole of its 1 000 

 will be usefully applied. 



Tredgold, Mr. Scott Russell, Dr. Arnott, and other writers on this 

 subject have given the results of their calculations as to the quantity 

 of steam and steam-pipe thus required. Dr. Aruott, after taking into 

 account the loss of heat through the thin glass of windows, through 

 the thick walls of buildings, and through various openings and crevices, 

 arrives at the following result : In a winter day, with the external 

 temperature at 1 below freezing, to maintain in an ordinary apart- 

 ment the agreeable and healthful temperature of 60, there must be of 

 surface of steam-pipe, or other steam-vessel, heated to 200 (which is 

 the average suriace temperature of vessels filled with steam of 212), 

 about one foot square for every six feet of single-glass window of usual 

 thickness ; as much for every 12n feet of wall, roof, and ceiling of 

 ordinary material and thickness ; and as much for every six cubic feet 

 of hot air escaping per minute as ventilation, and replaced by cold air. 

 A window with the usual accuracy of fitting U held to allow about 

 8 feet of air to pass by it in a minute ; and there should be for ventila- 

 tion at least 3 feet of air a minute for each person in the room. 

 According to this view, the quantity of steam-pipe or vessel needed, 

 under the temperatures wipposed, for a room 16 feet square by 12 feet 

 high, with two windows, each 7 feet by 8 feet, and with ventilation by 

 them or otherwise at the rate of 16 cubic feet per minute, would be 



For 4 1 nqure feet of glus, requiring 1 foot for 6=7 

 1J38 feit of wall, Milmg, &c., 1 foot for 120 = loi 

 ,, IS feet per minute TcutiUtlon 1 foot for 6 = 2 j 



20 



that U 20 feet of pipe 4 inches in diameter, or any other vessel having 

 the same extent of surface. 



Mr. Scott Russell's calculations had relation to the quantity of water 

 and of fuel required, as well as that of the steam-pipe ; and he arrives 

 at the conclusion that a room containing 600 cubic feet of air, and 

 exposing 400 feet of surface, may be maintained at a temperature of 

 -" above that of the air without that is to say, at 60 in the inside 

 of the room when the atmosphere is at 40 without for a space of 

 twelve hours, by the evaporation of two gallons of water, and at the 

 expense of about three pounds of coal. This calculation rests on the 

 maintenance of the required temperature so far as the room and its 

 contents are concerned; but the change of the air requisite for a 

 person living in the room disturbs the formula, and brings into it 

 many new elements. 



Thi* mode of heating buildings is adopted to a large extent in 

 Lancashire, Yorkshire, and Cheshire, In the steam-power factories. 

 In the cotton-mills, woollen-mills, flax-mills, power-loom factories, dye- 



works, bleach- works, print-works, Ac., the facilities for producing an 

 uninterrupted supply of steam are so great, that the stoam-heating 

 system becomes by far the most economical that can be employed. 

 Orrell's cotton-mill at Stockport may be taken as an exemplification i 

 a large class of such buildings. This mill is situated on the banks of 

 the Mersey, and occupies a ground area of 280 feet by 200 feet It in 

 six stories in height, and has several distinct apartments 280 feet in 

 length each. All the preparatory processes are effected in the upper 

 stories ; while the weaving and finishing are conducted below ; but all 

 the rooms and galleries are alike boated by large steam-pipes, running 

 the whole length of the rooms, and conveying steam from one end of 

 the building, where the boilers are situated, which furnish not only 

 this supply of steam, but also that required by four steam-engine* 

 employed in the mill The steam is admitted to the heating-pipes in 

 quantity proportionate to the coldness of the weather. 



A very large structure at New York, presented to the city ss a 

 museum and lecture-room, and called the Union Building, affords a 

 good example of the steam-heating system. There are no less than 

 eight miles of small pipe arranged in the basement, filled with high- 

 pressure steam. A fan-blower, twelve feet in diameter, sends a vast body 

 of air rapidly through the pipe-rooms ; and the air thus wanned finds 

 its way into spaces beneath every floor. A hole of one inch diameter is 

 made through the floor under every chair or seat in the lecture-hall, 

 2300 in number ; up these holes warm air is sent in winter, and cold 

 air in summer. 



Warming by Hot Water. The principle on which the hot-water 

 method is founded is different from all the others which have passed 

 under our notice. When a vessel of water is heated, the water does 

 not become hot by the conduction of caloric from particle to particle, 

 but from the ascent of heated particles from the bottom, where we 

 suppose the heating agent to be applied, to the upper strata. This is 

 proved from the circumstance that if heat be applied only to the 

 surface of the water in a vessel, it is by extremely slow degrees that 

 the lower strata becomes heated. Heat being applied to the bottom of 

 a vessel, the lower strata of particles, becoming specifically lighter than 

 before, ascend, while the colder particles at the surface descend to 

 supply their place; and hence a series of ascending and descending 

 currents is formed. Now, if, instead of having the heated water 

 only iu a vessel, it ramify also through closed tubes connected with 

 the vessel, the ascending and descending currents may be passed 

 through different parts of a building, besides the room where the 

 vessel itself may be placed. The heated water, rising to 21 2, or to any 

 temperature depending on the fire to which it is exposed, gives out 

 heat to the metallic pipe through which it passes, and this pipe again 

 communicates heat to the air of the room. Hence the operation of this 

 method of warming depends on the circulating, or ascensive and descen- 

 sive property of heated water, by which the portions of pipe farthest 

 removed from the fire become as much heated as those in its immediate 

 vicinity. 



Where all the apartments to be warmed are on one level, an open 

 boiler may be used ; but where it is necessary to carry the pipes to 

 different floors of a building, some of them much above the !< 

 the boiler, the boiler must in that case of necessity be closed. \Yl-n 

 an open boiler is employed, a pipe branches out from the upper partoi 

 the side, extends horizontally through the rooms to be warmed (with 

 out in any case rising above the level of the water in the boiler), anil 

 returns again to the boiler, which it enters at a lower level tli 

 other. Under this arrangement a current of heated water will flow 

 from the boiler at the upper orifice, and, after traversing the tube, 

 return to the lower orifice. A closed boiler is, however, more exten- 

 sively useful, since it enables all the stories of a building to be warmed 

 by one apparatus. The whole system, including both tubes and boiler, 

 is filled with water at a valve at the highest point ; and when heat is 

 applied to the boiler, a circulation ensues which speedily causes the 

 whole length of tubing to become hot. In this form of the apparatus 

 the temperature of the water is kept down to a moderate pitch, in 

 order to avoid danger ; but in a modification of it, called the " high- 

 pressure " method, the boiler consists of a coil of pipe forming part of 

 the circulating pipe, and is capable of being safely heated to such a 

 degree that the pressure of the water within equals lOOOlbs. on the 

 square inch. The whole system of water circulation is brought to so 

 high a temperature, that the metal of the pipes warms the air of a 

 large building very speedily. 



Many large and important buildings are warmed on one or other of 

 these two hot-water systems mostly on that with the closed boiler. 

 The hot-water apparatus put up by Mr. Perkins in the British Museum, 

 for warming the rooms formerly used by readers, suggested the plan 

 which U adopted for warming the present magnificent reading-room. 

 This room is warmed by three boilers, the furnaces of which consume 

 their own smoke. Main pipes conduct the hot water from these 

 boilers to smaller pipes, which bring it into the room, and the water I In u 

 returns by other pipes to the same boilers. There is an air-shaft 

 whii-li reaches the full height of the building, having windows in it to 

 admit fresh air. There is a fan, or blower, at the bottom of the shaft. 

 Air is forced from the shaft through valves into arched brick chambers, 

 whence it cannot return. This air is filtered through a \vii. 

 and is then conveyed up into the reading-room not to warm it, Imt 

 to keep up a supply of pure air. The doors of the room are made 



