62 



HEAT. 



FIG. 49. 



\ 



Arrangements have been made by which the incoming cold air is 

 warmed by some of the excess of heat which 

 would otherwise be wasted up the chimney. The 

 air is admitted from the outside into boxes placed 

 round the grate and chimney, and then carried into 

 the room preferably to the furthest corner from 

 the grate, somewhat as in Fig. 51. If the entrance 

 into the room is sufficiently subdivided, no serious 

 draughts will be felt. 



In large rooms used for meetings, the problem 

 of warming, and at the same time ventilating, 

 efficiently, is one of great difficulty, and one which 

 architects have only very partially solved. The 

 shape of the building and its surroundings may 



greatly influence the direction in which convection-currents tend to 

 establish themselves, so that it is 

 almost impossible to foretell the special 

 difficulties to be surmounted. As 

 there is in such halls, generally, 

 nothing corresponding to the open 

 chimney, ventilators are usually pro- 

 vided near or in the ceiling, and the 

 whole room may be in this case 

 regarded as a chimney. The air of 

 the room is warmed by the heating 

 arrangements and by its occupants, 

 so that a circulation is established 

 through door or window, or through 

 other communication, with the external 

 air and out through the ventilators. 

 Frequently, however, especially in cold 



weather, local circulation is established near the windows, the air in 



contact with them being cooled, 

 and falling through its increased 

 density, this fall being recog- 

 nised as a cold down-draught. 

 This may be lessened either 

 by having double windows, or 

 warming the windows by gas- 

 jets or water-pipes placed in the 

 inside sills. Probably, the most 

 common fault in large rooms is 

 that, from motives of economy 

 in construction, the ventilation 

 is left too much to work itself. 

 Some means, such as a fan, 

 should always be provided, by 

 which the impure heated air 

 should be extracted at the top, 



while fresh air, warmed if necessary, should be introduced at such a level 

 and in such a direction that it will not be felt as an unpleasant draught 



FIG. 50. Tobin Ventilation. 



I i 



FlG. 51. Arrangement for Warming 

 Incoming Air. 



