How to Cool a House With Evaporative Coolers

Evaporative coolers --- or "swamp coolers" --- use water to push warm air out through open windows to keep homes naturally airy and cool. According to Energysavers.gov; "Evaporative coolers cost about half as much to install as central air conditioners and use about one-quarter as much energy." Because evaporative coolers provide natural humidity, they're best used in dry, desert-like climates.

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  1. Select the right size evaporative cooler for the room or area you want to cool. Evaporative coolers are rated by the number of cubic feet per minute (CFM) of cooled air that flows into a room. Typical models (from portable types to whole house duct systems) are sized from 3,000 to 25,000 CFMs. Figure out the cubic feet of the area you want to cool and divide by two to determine the appropriate size cooler you need.

  2. Decide if you want your cooler to blow air into one or more smaller rooms (as in a central location installation) or to cool your entire house (as in a ducted system installation). Portable swamp coolers -- or horizontal-flow coolers --- are installed in a single window and are good for cooling one room or a small part of your house. Ducted systems are ideal for large homes with hallways and many bedrooms to cool.

  3. Open windows in different rooms and at varying heights to experiment with temperature and humidity levels. If your windows are open too much, you'll feel the hot air coming in and your cooler will operate less effectively. If your windows aren't open enough, you'll get more humidity than you bargained for. Close windows in rooms that aren't being used.

  4. Maintain your evaporative cooler so that it runs efficiently throughout the summer. Change the pads and filters at least twice during the cooling season. Check the pump and reservoir for sediment accumulation and clean it out regularly. Evaporative coolers need to be thoroughly cleaned at the beginning of every season.


  • Portable swamp coolers that sit in the window aren't suitable in extremely hot weather.
  • Evaporative coolers with up-ducts installed will need more attic ventilation.
  • Evaporative coolers use a lot of water and may be a concern in dry climates where water supply is rationed.
  • Down-flow swamp coolers installed on the roof may cause roof leaks and more difficult maintenance.
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