DEVELOPMENT OF HOUSE HEATING 



127 



A furnace should have such a perfect circulation that the jacket 

 never becomes very hot. The purpose of the furnace is to 

 send heated air into the rooms above and not to heat the 

 basement. 



HOT WATER HEATING 



145. Principles of Heating by Hot Water. In heating 

 houses by means of hot water, we depend largely upon the 

 same principles as in furnace heating. In the furnace we 

 depend upon the heating of the air and the consequent ex- 

 pansion of it to produce the circulation; so here also we depend 



FIG. 95. A hot water system. 



upon the heating of the water and the consequent expansion 

 of it to produce the necessary circulation. 



The WATER HEATER is usually placed in the basement (Fig. 

 95). The hot water flows from the highest point of the 

 heater through the MAIN FLOW PIPES to the radiators placed 

 in the various rooms. From the radiators, the cold water 

 returns through the RETURN FLOW PIPES to the bottom of the 

 heater. In passing through the radiators, the water heats 

 them and they in turn heat the air in the rooms, producing 

 convection currents precisely as the stove does. 



The water cannot be kept in circulation without some active 

 force to keep it moving. It is easily seen that we have 



