Understanding Swamp Coolers Understanding Swamp Coolers

You could almost think swamp coolers were one of the latest developments in home cooling technology. Energy efficient, only use natural materials and have no potentially toxic gases, able to cool a home on a hot day as much as 10º F, and best of all, the hotter it gets, the better they work. However, swamp coolers aren’t a new idea, in fact, people living in hot arid areas have known and used evaporative cooling for hundreds of years. However, with our growing concern about the environment, the idea of swamp coolers (or evaporative coolers to give them their proper name) is enjoying resurgence.

How does evaporation cause cooling?

  • When warm, dry air passes over something wet, a little of that moisture will be absorbed and the air gets cooled as some heat moves from the higher temperature of the air into the water. It’s the same process nature uses to control our body temperature using perspiration - as our perspiration evaporates, we feel cooler. That’s why swamp coolers work better as temperatures climb - hotter air will absorb more water and as a result, be cooled more.

How do swamp coolers cool?

  • A swamp cooler is essentially a box containing a fan that has water moistened positioned in front of it. When the fan is running it draws in warm outside air and pushes it through the moistened pads effectively cooling the air while adding some moisture to it. There is usually a secondary fan in the swamp cooler to push the now cooled air out into the room.
  • The pads are commonly made from cedar or aspen shavings (that resist mold) and are kept moist by a constant flow of water dripping onto them from a small pipe.
  • In addition to lowering the air temperature, swamp coolers have a secondary cooling effect caused by the creation of a constant flow of air and this cooling breeze that makes people in a room feel about 5ºF cooler than the air temperature.

Are they really good?

  • Swamp coolers use substantially less energy than air conditioners and since they operate on 120 Volts household current even a large central unit can be simply plugged into a regular outlet. As well, because the technology is so simple, swamp coolers cost much less than air conditioners.
  • In addition, by keeping the air in a home humidified, swamp coolers prevent wooden furniture and floors from drying out. Plus, the pads act as an air filter, keeping air borne dust and pollen out of the room and making breathing easier.
  • Finally, swamp coolers work best when at least one window in a house is open, as opposed to an air conditioner that requires all windows be closed. So, swamp coolers help get rid of household odors and ensure a constant supply of fresh air into the home.

Sounds really good, do they have a downside?

  • Unfortunately, swamp coolers aren’t the solution for everyone. Since they only work in areas and climates where the air is predominantly hot and dry, swamp coolers are ineffective or even useless in regions with mainly hot, humid conditions. In other words, a swamp cooler won’t work in a swamp.
  • Plus, since swamp coolers require a constant flow of water, in areas where water is scarce, swamp coolers can put major strain on a home’s water supply.


Murray Anderson is an experienced freelance writer with over 500 articles published on the web as well as in print magazines and newspapers in both the United States and Canada. He writes on a wide range of topics and is a regular contributor to DoItYourself.com. He can be contacted at [email protected].

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