The swamp cooler is becoming more and more popular as a cost effective way to cool or an automotive shop. They do not rely on the standard refrigeration process in order produce cooler air. A typical swamp cooler uses good old fashion evaporation to cool air in a room. This evaporation process is both energy efficient and easy on  the environment. Swamp coolers have been used for decades in dry, desert climates where they work the best, but you will also see these units behind the benches of your favorite football team in those hot September months. Auto shops have also started using them as an inexpensive way to keep their shops cooler and mechanics more productive. However, there may be some confusion on how they operate and how to select the correct size swamp cooler.

The temperature of air coming out of an swamp cooler obviously depends on the temperature and the humidity of the air going in. A swamp cooler can deliver comfortable air under a wide variety of typical summertime temperature and humidity ranges.

In addition to dropping the temperature of the air, evaporative cooling offers an additional cooling benefit. The constant movement of the air created by the blower - the cooling breeze it creates, if you will - makes the occupants of a room feel 4 to 6 degrees cooler than the actual temperature. This is the same effect you feel when you turn on a ceiling fan or a simple window fan. For this reason, the "effective temperature" created by an evaporative cooler will feel 4 to 6 degrees cooler than temperatures shown on the chart.

An added benefit of evaporative cooling is that it works best in the hottest time of the day. As the temperature outside increases as the sun climbs, the humidity normally drops. In the early morning, for example, the temperature may be 70 degrees, with a relative humidity of 60 percent. By mid-afternoon, when the temperature has climbed to 90 degrees, the humidity may well have dropped to 30 percent - conditions that make the swamp cooler work more effectively.

 
For a swamp cooler to effectively cool, it must be the proper size for the job. A small portable unit, for example, will not adequately cool a large-sized room.

While the output of air conditioners are rated in BTUs (British Thermal Units), portable evaporative coolers are rated by CFMs (the cubic feet per minute of air that the cooler can blow into your home).

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