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Swamp Cooler Quick Guide - All About Evaporative Coolers

A swamp cooler (also known as an evaporative cooler) is essentially a box-like frame containing a fan that is walled in by moistened pads, usually made of cedar shavings or cellulose.

The fan takes in hot air from the room and sends it through the dripping pads (which are kept soaked by a water pump), cooling the air by about 20° F as the water molecules evaporate from the pads.

The fan then blows the water-cooled air back into the house and out a vent (usually an open door or window) to maintain a balance in the air pressure of the building.

Swamp cooling units can be either portable or stationary, or roof or window mounted, systems. Portable swamp coolers can be moved from room to room while the stationary systems, especially the roof mounted units, remain in one place and create a central cooling system for the entire building.

How are swamp coolers different from air conditioners?

Air conditioners use a compressor to cool the air, which is a much more efficient method than that of a swamp cooling unit. Air conditioning can bring down the temperature based on the thermostat, shutting off and on automatically, opposed to manual or remote control like swamp cooling.

Air conditioners also displace hot air outdoors and cool the inside air with the refrigerant contained in the system. However, air conditioners require venting kits to aid in hot air removal while also dehumidifying the air.

If you are in a dryer climate, where the relative humidity is below 50%, a swamp cooler may be a better choice for your cooling needs. Not only is it a more cost effective means of cooling your building, but it will humidify the air in your space as well.

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What size evaporative cooler do I need?

Swamp coolers vary in size from small, portable units, to large, roof mounted units. The size you need will depend on how much space you want to cool and what the relative humidity is in your area.

Portable swamp coolers are the most versatile systems for a home or small office. They can be moved from one room to another to cool smaller areas, which can be a more cost effective method if there are rooms that are occupied more frequently than others.

Portable swamp coolers can range in size from approximately 20 to 42 inches high, but don't be fooled by the size. Some of the smaller units can cool up to 600 square feet of area while some of the larger units may cool smaller areas.

For larger buildings (such as an office building) and for arid climates, a roof mounted unit is probably the better choice because it provides similar results as central air conditioning. Using the same type of duct work as a central air conditioner, the swamp cooler can be used to cool many rooms in one building.

Whatever size evaporative cooler you choose, remember that it has to be used in a fairly dry climate in order for it to work effectively and efficiently. Also keep in mind that swamp coolers can cool the air by about 20° F and will also act as a humidifier.

How does a swamp cooler work?


The way a swamp cooler operates is fairly simple. There is a motor which pumps the water from the bottom of the cooler to the top, where it falls down the sides and along porous filter pads. A second motor drives a fan which pulls hot air through the unit and then pushes it into the hot room.

The main cooling action is the water evaporating as the air passes through the cooling unit. (Coincidentally, the water level is kept constant in the larger units with the help of a floating sphere functioning similar to the one in a toilet tank reservoir.

The portable units have tanks that require filling on a regular basis or have tanks for ice, which also needs to be replaced on a regular basis.) The hot air enters the swamp cooler, where two small motors power nothing more than a fan and a pump, which sends cool air into the hot room.

Does a swamp cooler require much maintenance?

Larger window and roof mounted swamp coolers typically need to be maintained at the beginning of the cooling season (usually around May or June), as well as the end of fall, depending on the location.

To maintain large swamp coolers, be sure to have all of the necessary tools at hand. A screw driver will be needed to remove screws for the access panel, wrenches or pliers to hook up the water supply, and an oil can for oiling the motor. Use a garden hose for cleaning up any debris and a flashlight to help you view inside the corners of the unit for anything that might clog the air or water passage.

If the evaporative cooler is mounted on the roof, you will have to climb up to perform the maintenance. Please be sure to take any and all necessary precautions when maintaining any outside cooling unit.

Maintaining a portable swamp cooler is quite a bit easier than maintaining a larger unit. In fact, most models do not require much maintenance at all, other than adding water to the tank when necessary. Depending on your needs along with ability and tolerance of higher spaces, a portable swamp cooler may be the best choice.

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