How to Use an AC With a Swamp Cooler

Swamp coolers work best in low-humidity locales.

Evaporative coolers, also known as "swamp coolers," are a simple, low-cost way to use evaporation for cooling. Swamp coolers are an effective cooling system only in low-humidity climates or seasons, while air conditioning cools the air despite high humidty. Since a swamp cooler draws in dry air, the house needs to have at least one window or door open; air conditioners need to have all windows and doors closed. So in a state like Arizona, you can use a swamp cooler during the hot, dry summer months and your air conditioner during the rainy season.

Things You'll Need

• Air conditioner
• Swamp cooler

Instructions

Operation of swamp coolers and air conditioners

1. 

   Central air conditioning requires ductwork.

   Depending on the season and the humidity, you have to decide which of the two cooling systems to use. If using a swamp cooler, you need to keep open one window or more because the warm indoor air goes outside through open windows or doors as the cooled, fresh air replaces it. The air is pulled in through moist pads and then blown throughout the house. Cooling by evaporation can drop the temperature from 15 to 40 degrees Fahrenheit. In hot climates, people often use sleeping porches, and in the 1920s in the Arizona desert people would hang wet bed linens on their porches and use an electric fan to pull air in through the sheets or blankets for cooling. This evolved into the swamp cooler, which can be plugged into any outlet. The devices do use a lot of water; if you don't use it with its water pump, you can use a swamp cooler as a whole-house fan, weather allowing.

2. 

   You can plug a swamp cooler into any outlet; central ACs require a separate circuit.

   Since air conditioners recirculate the air, you have to close all windows and doors when using it. ACs require a separate circuit and they use three to five times as much electricity as a swamp cooler.

3. 

   Shade plants and awnings help keep a house cooler.

   Since you can't use them at the same time, you must decide which system to use. In Arizona you can use a swamp cooler in summer. But in a humid climate, its use depends on the amount of humidity. At 30 percent humidity on a hot day, you can still use a swamp cooler. But if the humidity is higher than that, you need an air conditioner to stay comfortable. The University of Arizona Cooperative Extension website advises shading windows and walls and insulating walls to control heat and humidty.

4. 

   You need open windows when using a swamp cooler.

   To ensure security when using a swamp cooler, you need ceiling vents or up-ducts that vent into the attic --which means extra ventilation in the attic -- or window stops, since windows have to be left opened part way. If your windows are open too far, hot air comes in; if they're not open enough, humidity increases. There is no formula for determining it; you have to figure out what works in your house.

Tips & Warnings

• Swamp coolers use a lot of water; in dry areas and droughts, and periods of water-use restrictions, this is a problem.

References

• California Energy Commission: Consumer Energy Center: Evaporative Cooling: How an Evaporative Cooler Works
• The University of Arizona Cooperative Extension: Evaporative cooler water use
• U.S. Dept. of Energy: Energy Savers: Evaporative Coolers

Resources

• Wonder Quest: Swamp Coolers