Evaporation is the most energy efficient cooling method. It was described and used by Ben Franklin, who explained that, “Liquid evaporates by shedding molecules into the air, changing from a liquid state to a gas …” which draws heat from hotter air and cools it as the water and air (molecules) “find equilibrium.” The remaining liquid is also cooled, “as hotter, faster-moving molecules are the most likely to escape into the air” (Read more at: http://home.howstuffworks.com/home-improvement/heating-and-cooling/swamp-cooler1.htm).

Evaporative, or “swamp,” coolers are used to cool indoor spaces using this method of air circulation and water. The process resembles the human perspiration process. Evaporative coolers are cost effective alternatives to air conditioners or conventional air cooling systems that typically use refrigerants in vapor-compression / absorption refrigeration-type cycles.

Evaporative Coolers

An evaporative cooler is not effective in all climates. It is particularly useful, however, in hot, dry climates. The main component inside the cooler unit is the blower / fan. The unit’s fan draws air in from outside through dampened fiber pads. Water drips over the fiber pads while the air is being drawn in. The pump prevents the pads from drying out completely. Humidity is produced which cools the building’s interior space. Energy required to operate an evaporative cooler is equivalent to that of a standard box fan.


Air ionizers are features added to evaporative coolers that clean impurities, dirt, dust, and other contaminants from the air drawn into the unit, before it is cooled and discharged. Ionizers work by releasing ions that are negatively charged that stick themselves to dirt and dust molecules, allergens from pet dander, and bacteria that cause viruses and diseases such as asthma. It has been proved that ionizers reduce respiratory and blood pressure rates and increases infection resistance.


Proper and regular maintenance is necessary to ensure all unit parts are clean and functioning and water remains clean and the discharged air is free of harmful bacterial contaminants.

The filter pads and water reservoir should be thoroughly cleaned every spring to ensure proper evaporative cooler performance. The back cooler panel may be opened so old pads can be removed and stale water may be drained (out of the drain plug or by using a siphoning hose).

Stiff-bristle brush the inside and vacuum out dirt and dust. White vinegar added to the water reservoir loosens residue that can be flushed away. Seal any reservoir leaks using silicon sealant. New fiber pads should be cut (using the old pads as a pattern) and fitted on the unit’s sides and back panel.

The motor and fan should be lubricated, the reservoir refilled and float adjusted, and the pump and fan checked to ensure water is appropriately trickling and the fan is properly operating.