VENTILATION AND HEATING. \\J 



main, the action of the heat of the stove is to make a 

 current of warm air up from the stove, which current 

 passes along the ceiling to the more distant corners of the 

 room, then descends, joining the cold air, and repeating 

 the round. 



A Stove and Jacket. In some cases a jacket is placed 

 around a stove, and a duct from the outer air connects 

 with the lower part of the space inside of the jacket and 

 outside of the stove. Then as the air heated by the stove 

 rises, fresh air is drawn in from outside to be warmed. 

 In this case the direct heat from the stove is shut off from 

 the room. Heat radiates in straight lines. When one 

 holds out his hands beside a stove the heat he receives is 

 radiant heat. Most of the heat from a grate is radiant 

 heat. But in a jacketed stove the heating by air currents 

 is called heating by convection. 



The Furnace. Now a furnace is practically a jacketed 

 stove (almost always placed in a basement). Furnaces 

 have this good feature that they are all the time sending 

 fresh air into a room. 



Foul-air Shafts and Fans. Although in private dwell- 

 ings heated by furnaces there is no special provision for 

 the escape of foul air, there is ordinarily sufficient renewal 

 of the air. But in public buildings there should be escape 

 flues for foul air. 



Frequently a large foul-air shaft is built in some central 

 part of the building, and a small stove placed in it to create 

 a sufficient up-current. In many public buildings the cur- 

 rents created by heat are insufficient to renew the air 

 properly. Fans are used, which force the air, properly 

 heated, into the room. 



