14 MASS. EXPERIMENT STATION BULLETIN 360 



Cooling and Ventilating 



Three types of cooling and ventilating equipment are available: viz., natural 

 air m9vement, exhaust fan, and intake fan. The most commonly used has been 

 the exhaust fan, but recent experiments and practice indicate that the intake fan 

 is as good or better and is less expensive to install. 



The exhaust fan system consists of a fan of proper size, installed just beneath 

 the ceiling in the center of one wall, and inlet openings at the floor level on the 

 opposite wall. The combined area of the inlets should be twice the area of the 

 fan. The fan should have a capacity to give a complete air change every five 

 minutes. That is, a room 40'x60'xi0', having a capacity of 24,000 cubic 

 feet should have a fan capable of moving 4,800 cubic feet per minute. This is a 

 fan capacity of ]4 cubic foot per minute per bushel of apple capacity. 



Table 2. — Fan Sizes. 



The more recently developed practice of driving in cold air and building up 

 pressure to force it down through the stacks of apples and finally out through 

 ports at the same end of the room as the fan, is a reverse of the exhaust-fan 

 practice. In this system the fan is located just beneath the ceiling in the center 

 of one wall, so set that outside air is forced into the room. The outlet ports are 

 placed on the same wall as the fan and just above the floor level. The sizes of 

 fan and ports are the same as recommended in the exhaust system. 



Storage Costs 



A good air-cooled storage may be provided at an initial outlay of from twenty 

 to fifty cents per bushel of capacity. This variation is caused by the fact that 

 some storages are adapted from an existing structure, while others are built new. 



Using fifty cents per bushel of capacity as a cost figure and a 3,000-bushel 

 capacity as an example, storage costs will amount to about five cents per bushel 

 per year, including interest, depreciation, taxes, and other charges. 



