What is a Swamp Cooler?

It sounds kinda... icky.

If you're used to living in humid areas, the sight of a swamp cooler on Tucson roofs might leave you with a quizzical look on your face.

When you drive around Tucson, you'll see some houses, mostly the older homes, with air-conditioner sized boxes on the roof, except they'll have dozens of small slats along the each side. These are swamp (or evaporative) coolers.

Attached inside each side panel is a pad -- either made of aspen tree shavings or synthetic material. The bottom of the cooler holds a tray of water that is pumped up and over to the pads, so water drips down the pads, wetting them thoroughly. A huge blower wheel inside pulls the hot outside air through the wet pads, cooling the air by adding water to it, then blows it through the air ducts in the house.

There are a couple models (Master Cool and Aero Cool) that have only one very thick pad in the front rather than one on each side. They work under the same principle, though.

These coolers are much more economical than air conditioning, and are quite simple to maintain, but their downside is they don't work well in humid weather (like during our Monsoon season) since the air is already water-saturated.