Ours comes into the house (via an air duct) through the wall, rather than the roof. It's a large metal box with four sides made of removable vent panels filled with what looks like mats of hay or straw (the cooler pad).
The fan runs, sucking air through the water soaked pads and blows cool air into the house. You draw the cool air around the house by cracking windows about three fingers wide.
This works only in dry climates, not during rain or humidity. Thankfully we have little humidity in our area of Idaho and our average precipitation per year is less than 9 inches!
Why am I explaining this to you? Masochism aside? Because Hubbers had to "cowboy up" the cooler today. I don't tolerate heat well and it's been toasty lately! He broke the switch that regulates the water flow and had to replace it, but we're good to go now! Too bad we're on the way out to a picnic in the park for our local La Leche League. Can't take the cooler with me...
- Estimated cost for installation is 1/8 to 1/2 that of refrigerated air conditioning
- Estimated cost of operation is 1/4 that of refrigerated air.
- Power consumption is limited to the fan and water pump vs. compressors, pumps, and blowers.
- The constant and high volumetric flow rate of air through the building reduces the age-of-air in the building dramatically.
- High temperature, high humidity outside conditions decrease the cooling capability of the evaporative cooler.
- Evaporative coolers require a constant supply of water to wet the pads.
- Water high in mineral content will leave mineral deposits on the pads and interior of the cooler.
- The water supply line needs protection against freeze bursting during off-season, winter temperatures. The cooler itself needs to be drained too, as well as cleaned periodically and the pads replaced.
Click on the swamper image for a larger view, or visit Wikipedia for more info.
Cool drinks image via MorgueFile.