SCIENCE OF HOME AND COMMUNITY 



The hot-air furnace. One disadvantage of heating by 

 stoves lies in the fact that several stoves are needed to warm 

 the whole house. Hence, systems are now very widely 

 used in which the whole house is heated from one furnace 

 located in the cellar, the heat being carried to the various 



rooms by means of 

 either hot air, or hot 

 water, or steam. The 

 hot-air furnace is a 

 large stove sur- 

 rounded with a metal 

 jacket, with' space be- 

 tween to allow air 

 to circulate. Air is 

 brought into this in- 

 closed space by a duct 

 leading from out- 

 doors, from the cellar, 

 or from the rooms 

 above ; and as it passes 

 over and around the 

 furnace it becomes 

 heated. The furnaces 

 are constructed so as 

 to give a large heating 

 surface. From the 

 top of the air jacket, 

 pipes lead to the sev- 



FIG. i. Hot-air system. 



eral rooms to conduct the hot air through registers placed 

 either in the floor or on the walls near the floor. Fre- 

 quently these pipes are covered with asbestos to reduce the 

 loss of heat. Each pipe usually has a damper near the 

 furnace and a register in the room that may be opened or 

 closed, by means of which the hot air supply may be shut 

 off from one part of the house and sent to other rooms. 



