Take the “Swamp” Out of Swamp Cooler

Two stage evaporative coolers are a high tech version of the conventional, single stage swamp cooler. The

advantage a two stage cooler has over the conventional swamp cooler is the production of cool air with 10%-30% less humidity – depending on your climate.

A conventional swamp cooler, by its nature, adds moisture to the air it cools. To reduce the moisture, a pre-cooling, first stage was added.

In the first stage, warm, dry air is pre-cooled by passing through a heat exchanger cooled by evaporation on the outside. Because the air supply to the second stage conventional evaporator is pre-cooled, the end result is cool air with 50%-70% relative humidity compared to 80% humidity from a traditional swamp cooler.

An additional benefit of first stage pre-cooling and reduced humidity is extending the product’s usefulness into hotter and more humid conditions.

The largest units have a cooling capacity of 3 tons, a supply air flow of 1,400+ cubic feet per minute and consume around 3 gallons of water per hour. This is sufficient cooling capacity for up to 1,700 square feet of living space.

According to the American Society of Heating and Engineers (ASHRAE), two-stage evaporative coolers can reduce energy consumption by 60 to 75 percent over conventional air conditioning systems.

Coincidently, I found a study by the Department of Energy simulating the annual power consumption of different cooling systems in a prototype house in Borrego Springs, California. The two systems I chose for comparison from the study are a 13 SEER, 3 ton, DX (Direct Expansion) air conditioner and a variable speed, 3 ton Oasys brand two stage evaporative cooler.

According to the study, the air conditioner consumed 3248 kWh (kilowatt hours) of electricity during the cooling season. Using the average California retail electric rate (2007) of $0.1435 per kWh, the resulting cost is $466. By comparison, the two stage evaporative cooler consumed 667 kWh of electricity for a seasonal cooling bill of $96, or 79% less than the air conditioner.

The new two stage evaporative coolers have successfully taken the “swamp” out of swamp cooler, but may face some resistance to the $3,000 price tag until the next wave of electric rate increases hits home.

For more money saving alternative cooling options, please visit Alternative Heating Info