What Are Evaporative Coolers?

In low-humidity zones, evaporating water can provide a natural and economical way of cooling. This principle is used by swamp cooler and evaporative coolers. Passing outdoor air over water-saturated mats reduces its temperature by 15-40 degrees F before it is brought into the home.

To allow the warm indoor air to escape when an evaporative cool is operating, windows must be partially opened. The cooler air will replace the warmer air. Evaporative coolers provide constant airflow to your home, as opposed to central air conditioners that recirculate the same air.

Evaporative coolers are approximately one-quarter to one-quarter the cost of central air conditioning and consume less energy. Evaporative coolers are less efficient than refrigerated ACs and require more frequent maintenance.


Evaporative coolers are rated by the volume of air they bring to the home. Most models offer a range of 3,000 to 25,000. Manufacturers recommend adequate air-moving capability for 20 to 40 air exchanges per hour, depending on climate.


Evaporative coolers can be installed in one of two different ways. They either blow air into central locations or connect to the ductwork, which distributes it to various rooms. Installing centrally is a good option for small houses that are open from one room to the next. Ducted systems will be required for larger houses, with multiple rooms and hallways.

Most residential evaporative chillers are installed on the roof with a down-flow arrangement. Many experts prefer to install horizontal units that are mounted on the ground. They are less likely to leak and require less maintenance.

To cool a specific room or area of your home, small horizontal-flow cooling units are placed in windows. These portable coolers are good for moderate climates. However, they might not be able cool a room well enough in hot conditions.

Also, small, portable evaporative coolers on wheels are now readily available. Although these units are portable, their cooling capabilities are limited by the humidity of your home. They will typically only have a slight cooling effect.


An evaporative chiller should have at most two speeds. There should also be a vent-only option. Vent-only operation prevents the water pump from operating and humidifies the outdoor air. This allows the evaporative chiller to be used as a whole-house fan during milder conditions.

By adjusting the windows, you can control the cooler’s airflow through the house. You can adjust the openings of the windows and vents on your leeward side to give you 1 to 2 square feet for every 1,000 cubic feet of cooling capacity. It is possible to experiment with the opening of windows and the amount they should be opened. Hot air can get in through windows that are too close to the ground. If the windows do not open enough, humidity can build up.

You can regulate the temperature and humidity of your home by closing all windows except those that are being used. If you have open windows that pose security risks, put up ducts in your ceiling. Up-ducts are designed to let cool air in through the evaporative cooler and exhaust warm air. Additional attic ventilation is needed for evaporative cooling units installed with up ducts.

Optional filters reduce the amount of dust in the incoming atmosphere, which is an appealing option for homeowners worried about allergies. Filters can also be used to reduce water droplets that coolers may pull from the fan blades. The majority of evaporative coolers do not include air filters. But, these can be fitted during or after installation.

Evaporative Cooler Maintenance

By draining your evaporative cooling system regularly, you can save time and money. Mineral build-up should be removed regularly. Evaporative coolers will need to be cleaned every season.

A cooler that operates for a long time will require more maintenance. In hot environments where the cooler operates a lot of the time, inspect the reservoir, pads, filters, and pump at most once a month. If the cool season is over, replace the pads at the very least twice.

Some cooler pads made from synthetic paper can be cleaned with soap, water, or weak acid depending on the manufacturer. When pads are changed, cleaned, or replaced, filters must be cleaned. Before servicing the unit make sure that you have turned off the electricity.

Two-Stage Evaporative Heaters

Two-stage cooling systems are much more efficient and newer than single-stage models. They come with a precooler, more powerful pads, and motors that are more efficient. They are more commonly used in areas where daytime temperatures often exceed 100degF because of their high cost.