How Evaporative Coolers Work

Nature's air conditioner

Evaporative coolers create cold air and lower the temperature in a room by forcing air through water saturated pads or panels.  The natural evaporation of water powers the dynamic cycle that allows evaporative coolers to work.  As water evaporates, it absorbs energy from ambient heat to complete its physical change from liquid to vapor.  For example, when you come out of the water on a hot day, the water on your skin evaporates into the air, so that even on the hottest day, you might experience a chill as your body temperature rapidly lowers. 

Evaporative coolers function in much the same manner-by drawing hot air through a wet medium using a fan or blower.  When water evaporates from the pads, it takes heat from the air with it, resulting in a dramatic cooling in the newly conditioned air.  The cold air is then pushed out of the system by the fan.

Whenever dry air passes over water, it absorbs some of the water. Evaporative cooling naturally occurs near waterfalls, rivers, lakes and oceans.  Since evaporation occurs more readily in air that is not yet saturated with water, evaporative coolers function best in hot, dry air.  In high humidity conditions, evaporation ceases because the air is already saturated with water vapor.

Why should I use an evaporative air cooler?

Other benefits

With evaporative cooling, a complete air change occurs every few minutes. Unlike the traditional "closed" system of a refrigerated unit, evaporative coolers function best when air can flow freely. 

The air in a room can be completely cycled through every few minutes, resulting in superior ventilation and increased air quality.  Constant cool air movement pushes heat out, along with stale air, smoke, odors and pollution.  The high volume of fresh, cool air produced by the evaporative cooler helps the human body ventilate naturally.  Evaporative cooling also helps maintain natural humidity levels, so wood furniture and fabric fibers do not dry out prematurely.

More information on evaporative coolers