Evaporative Coolers
These are not as common as refrigerated air conditioners. They are well suited to very dry areas, as found in the southwest. They operate by sucking in fresh air from outside across moist pads and cooling the air by evaporation.
There are two types of evaporative coolers:
- direct cooler: adds moisture to the air inside the home (considered beneficial when the climate is very dry)
- indirect cooler: does not add moisture to the air
To be efficient, coolers must be the correct size. Cooling capacity is measured by the fan pressure necessary to circulate cool air throughout an area (measured in cubic feet). This means that these units are normally rated in cubic feet per minute (cfm). As a guide, calculate the cubic area of your home in square feet, and divide this figure by 2. As an example, a 1,200 square foot house with 8 foot-high ceilings results in a cubic area of 9,600; divide this by 2 and it means that a 4,800cfm evaporative cooler would be necessary.