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What are Evaporative Coolers?

10/1/2013 11:54:52 AM | by Anonymous

Evaporative Coolers

Evaporative coolers are electronically powered device that cool air through the evaporation of water. They are used for climatic control under extreme arid areas. They are also known as a swamp or desert cooler. Evaporative coolers function differently from typically air conditioning systems that utilize vapour compression or absorbing refrigeration cycles. Evaporative coolers work by employing large amounts of water. The temperature of dry air can drop significantly through the transition of liquid water to water vapour. This can cool air without the use of much energy as compared to refrigeration. Wet cooling towers use the same principle as evaporative coolers. However, they are only designed for purposes other than directly cooling the air in a building.

In arid areas and low-humidity locations, the evaporative coolers can be a relatively familiar sight. They have the added benefit of conditioning air with more moisture for more comfort of building occupants. They can either be fitted into an opening in a wall or installed atop the roof of a building. One type of evaporative cooler offers access directly to the controls positioned on the front of the unit. Whereas, others are designed to pump the cool air through other methods such as heating, ventilation ducts within a building and air conditioning. All of these help provide an unobtrusive and effective method to cool hot and dry air. Forced air and refrigerated air conditioning are more commonly found in humid locales.

The mechanics of an evaporative cooler are generally simple. When a fan blows warm, external air over a rotating moist pad situated on a drum, it creates a cooling effect. A tray of water is placed at the base of the drum to moisten the pad. The water provided is via a flexible, thin hose attached to a water source. The entire cooling unit is placed in a metal box with multiple vents to the outside air.

Water usage is a huge consideration point in the desert. On a typical day during summer, approximately three to fifteen gallons of water may be expelled by a desert cooler to keep it cool. The purchase price is almost equal to air conditioners that are designed to cool a similar amount of space. An evaporative cooler uses up roughly double the size of a refrigerated air conditioner with only a sixth of the electricity.

Several air conditioners work best in cooled area that are sealed as tightly as possible from the outside air. However, an evaporative cooler requires windows to be cracked a couple of inches about for the optimal climate control to occur. A breach on the interior environment would allow hot air to move out and are replaced by cool, moist air. However, as the rate of humidity rises, the swamp cooler becomes generally less effective.

It is crucial to maintain the evaporative coolers for them to function over a long period of time. They need routine maintenance over seasonal climates. When temperatures fall below freezing temperature, the evaporative cooler needs to be flushed and covered with a canvas drape to protect it from freezing and eventually causing damage. During spring, it is reconnected and reconditioned for yet another season of hot evaporated air conditioning.


Some advantages of using evaporative coolers are due to their low cost as compared to a refrigerated air conditioning. They are slightly less expensive to install and operate. They also bring about the ease of maintenance, users need not spend hefty amount of money for the maintenance of the coolers. This is because there are only two mechanical parts, the fan motor and water pump. Both of which can be repaired at low cost and convenient by a mechanically inclined home owner. They also provide a constant high volume flow rate of ventilation air reducing the “age-of-air” within the building dramatically. In dry climates, it increases humidity. This helps to improve comfort and decrease static electricity problems.


There are also certain disadvantages alongside to its advantages. The coolers usually have higher dew point conditions. This would mean a decrease cooling capability of the evaporative cooler. There is also no dehumidification. The high humidity supplied by the coolers at 80% - 90% accelerates corrosion especially in the presence of dust. This shortens the life of electronic and other equipments. They would also require a constant supply of water for wetting the pads. The moist water pads are also a common area for mosquito breeding.


On top of just knowing what an evaporative cooler is and the mechanical functions, it is also important to weigh out the good and bad effects before deciding if the investment in an evaporative cooler would be a smart decision to make.


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