In low-humidity regions, evaporating water in the air can provide a natural and economical way of cooling. This principle is what evaporative coolers or swamp coolers rely upon. When outdoor air is passed over the water-saturated pad, it evaporates, reducing the temperature by between 15 and 40 degrees Fahrenheit before it is sent into the home.

Partially opening windows allows warm indoor air to escape while it is being replaced by cooler air. Evaporative coolers, unlike central AC systems, which circulate the same air, provide a constant stream of fresh air to the home.

Evaporative coolers can be installed for half the price of central air conditioners. They also use less energy and require about one-quarter the amount of maintenance. Evaporative coolers require more frequent maintenance than frigerated air conditioners. They are also less suitable for low humidity.

Installation

Evaporative coolers can be installed in either one of two ways. They blow air into a central place or connect to ductwork to distribute the air to different rooms. Installations at a central location work well in small houses that have open living spaces. Larger houses with multiple rooms and hallways will require a duct system.

Most residential evaporative coolers are installed on the roof in a downward-flow arrangement. Experts recommend installing ground-mounted horizontal units as they are more maintenance-friendly and riskless of roof leaks.

For cooling a small area of a home, horizontal-flow coolers may be placed in windows. These portable evaporative coolers work well in moderate climates but may not be capable of cooling a room sufficiently in hot areas. These coolers are increasingly popular in western states with milder summers. They can reduce the temperature in one room by between 5 and 15 degrees Fahrenheit.

These small, portable evaporative coolers on wheels are also now available. These units offer the convenience of being portable, but their cooling power is limited by humidity. These units generally provide only a slight cooling effect.

Operation

An evaporative cool should have a minimum of two speeds and a vent-only option. Vent-only operation does not allow the water pump to operate, and the outside air is not humidified. This allows you to use your evaporative cooler in mild weather as a whole-house fan.

You can adjust the window openings to control the cooler’s air movement throughout the house. Find the right window to open and the right amount of opening. To allow too much heat in, windows should not be opened too far. Humidity can build up in the home if they are not opened enough.

Temperature and humidity can be controlled by closing unoccupied windows and opening the windows in those areas. Install up-ducts to the ceiling in areas where open windows pose a security risk. Up-ducts allow warm air to escape into the attic while cooler air enters from the evaporative cooling system. Up-ducts are required to ventilate the attic for evaporative coolants.

Homeowners with allergies may find it attractive to purchase optional filters which remove most of the dust in the incoming air. Filters can be used to reduce the possibility that some coolers will pull water droplets out of the pads and into the fan blades. While most evaporative coolers do not come with air filters as original equipment, they can be attached to the cooler either during or after installation.

Evaporative Cooler Maintenance

Regular draining and cleaning of your evaporative cooler will save you time and money. It is important to remove all sediment and other minerals. Evaporative coolers should be cleaned thoroughly every season.

The cooler will need more maintenance the longer it is in use. In hot climates, where the cooler is used a lot, you should inspect the reservoir, filter, and pump at a minimum once a month. In cooling seasons, the pads should be changed at least twice and if the cooler is in continuous operation, every month.

Some cooler pads made of paper or synthetic can be cleaned using soap, water, or a weak acid according to the manufacturer's instructions. After the pads have been changed or cleaned, the filter should be cleaned. Before you service the unit, be sure to turn off the electricity.