FARM SANITATION 529 



nace, piping, and radiators of sufficient size. The capacity of 

 a furnace depends primarily upon its heating surface, al- 

 though the size is commonly designated by the size of the 

 fire pot. 



Radiators. Radiators, designed to give off heat from the 

 water heated in the furnace, are made of cast-iron, pressed 

 steel, or pipe. In any case the amount of heat furnished is 

 determined by the amount of surface from which the heat 

 may radiate. This is always measured in square feet, and 

 one feature of the design of a hot-water system is to provide a 

 sufficient amount of radiating surface to heat each room. 

 Radiators may be obtained with greater or less number of 

 sections in various sizes, to furnish any amount of radiating 

 surface desired. 



Estimating the Radiation. One rule for determining the 

 amount of radiation for climates where the temperature occa- 

 sionally falls below zero is as follows : 



cubical contents of room 



Square feet of radiation = — : — — ■ — ■ ■ ■ + 



200 

 square feet of glass 



+ lineal feet of exposed wall. 



2 



The hot-water system will successfully heat rooms on the 

 side of the house exposed to strong wind. It is much cleaner 

 and the plant will last at least twice as long as the hot-air 

 system. The cost will, however, be from one-half to double 

 that of the hot-air system. It is claimed that the hot-water 

 system uses one-third less fuel than the hot-air furnace. 



A steam system may be installed for heating residences, 

 but it requires close attention and so is seldom used.* In 

 large buildings and factories it is universally used, the use of 

 steam reducing to some extent the size and cost of piping. 



