SYSTEMS OF VENTILATION 



331 



stands within the room as in the case of ordinary DIRECT 

 RADIATION. At the base of the radiator, however, an opening 

 is made in the floor. Cold, fresh air is admitted through an 

 opening in the wall of the building; it then passes upward 

 through the opening in the floor past the radiator where it is 

 heated (Fig. 234). Usually a base board of wood or metal 

 around the base of the radiator prevents the cold air from 

 entering the room until it has 

 been heated by the radiator. 

 This direct-indirect system is 

 uncertain in its action and 

 generally considered rather 

 unreliable as well as expen- 

 sive. Recall the principles of 

 furnace heating and the rule 

 of installing a furnace (Arts. 

 141-143) and explain why it 

 is that this direct-indirect sys- 

 tem is not more reliable. 



364. Ventilation of School 

 Buildings. The problem of 

 ventilating school buildings 

 is also largely determined by 

 the size of the building and 



the mode of heating. The usual mode of heating a one-room 

 school is by means of a stove, occasionally by means of a 

 furnace, and rarely by hot water or steam. The heating of 

 large, many-roomed school buildings is usually by means of 

 steam heat, sometimes by hot water, rarely by means of stoves 

 or furnaces. 



365. Heating and Ventilating the One-room School. 

 Several practical devices have been perfected which ac- 

 complish the heating and ventilation of the one-room school by 

 means of stoves. They are based upon the principle of the 

 jacketed stove (Art. 140) with the addition of devices for the 

 admission of fresh air and the removal of foul air. Since any 



FIG. 234. Direct-indirect radiation. 



