HOT-WATER HEATING 



stove S, like all other stoves, has an inlet for air and an outlet 

 C for smoke; but in addition, it has built around it a chamber 

 in which air circulates and is warmed. The air warmed by the 

 stove is forced upward by cold air which enters from outside. 

 For example, cold air constantly entering at F drives the air 

 heated by S through 

 pipes and ducts to the 

 rooms to be heated. 



The metal pipes 

 which convey the heated 

 air from the furnace to 

 the ducts are sometimes 

 covered with felt, as- 

 bestos, or other non- 

 conducting material in 

 order that heat may not 

 be lost during transmis- 

 sion. The ducts which F COLD AW 

 receive the heated air FIG. 12. 

 from the pipes are built 

 in the non-conducting walls of the house, and hence lose practi- 

 cally no heat. The air which reaches halls and rooms is 

 therefore warm, in spite of its long journey from the cellar. 



Not only houses are warmed by a central heating stove, 

 but whole communities sometimes depend upon a central 

 heating plant. In the latter case, pipes closely wrapped with 

 a non-conducting material carry steam long distances under- 

 ground to remote buildings. Overbrook and Radnor, Pa., are 

 towns in which such a system is used. 



Hot- water heating. The heated air which rises from fur- 

 naces is seldom hot enough to warm large buildings well; 

 hence furnace heating is being largely supplanted by hot-water 

 heating. 



A furnace. Pipes conduct hot air to 

 the rooms. 



