An evaporated cooler is an electric powered air cooler that is used for climate control in extremely arid regions. Sometimes known as a desert cooler or a swamp cooler, evaporative coolers work opposite of the refrigerated air conditioners found in humid areas. Rather than removing moisture from the air, an evaporated cooler actually pumps moisture into the air, causing a significant cooling effect.
In the arid areas of western U.S. and other low-humidity locations, evaporated coolers can be a familiar sight. Desert coolers can be installed atop the roof of a building, or fitted into an opening in a wall. One type of evaporated cooler offers direct access to the controls on the front of the unit. Others are designed to pump cool air through heating, air conditioning and ventilation (HVAC) ducts within a building, providing an efficient and unobtrusive method to cool hot, dry air. Refrigerated air conditioning, or forced air, is more often found in humid locales.
The mechanics of an evaporating cooler are fairly simple. A fan blows hot, outside air over a moist pad that rotates on a drum, creating a cooling effect. A tray of water at the base of the drum moistens the pad. The water is provided via a thin, flexible hose attached to a water source. The entire cooling unit is housed in a metal box with multiple vents to the outside air.
Water usage can sometimes be a consideration in the desert. On a typical summer day, from 3 to 15 gallons (11.3 to 56.8 liters) of water may be expelled by a desert cooler. The purchase price is approximately equal to air conditioners rated to cool a similar space. An evaporated cooler takes up roughly twice the size of a refrigerated air conditioner, but only uses about a sixth of the electricity.
Some air conditioners work best when the cooled area is sealed from outside air as tightly as possible, but an evaporated cooler requires windows to be cracked at least a couple of inches (5.8 cm) for optimum climate control. A breach in the interior environment allows hot air to flow out and be replaced by cool, moist air. However, as the humidity rises, the swamp cooler becomes less effective.
Evaporative coolers need routine maintenance in seasonal climates. When temperatures dip below freezing, an evaporated cooler must be flushed and covered with a fitted canvas drape to protect it. In the spring, it is reconditioned and reconnected for another hot season of evaporated air conditioning.