Two stage volatile coolers are a relatively new addition to the family of alternative cooling appliances. The advantage two stage coolers have over conventional, single stage models is the yield of cool air with 10%-30% less humidity (depending on your climate).
The stages of a two stage cooler are described as "indirect" for the first stage, and "direct" for the second stage.
Homemade Air Conditioner Cooler
A accepted swamp cooler, by its nature, adds moisture to the air it cools. To offset this, a pre-cooling, or indirect stage, was added.
In the indirect stage, warm, dry air is pre-cooled by passing straight through a heat exchanger cooled by evaporation on the outside. Because the air contribute to the second stage evaporator is pre-cooled, the end follow is cool air with 50%-70% relative humidity compared to 80% humidity from a accepted single stage cooler.
An additional advantage of first stage pre-cooling and reduced humidity is extending the product's usefulness into hotter and more humid conditions.
Two stage volatile coolers are most often installed directly into an covering wall or at ground level supported by a small concrete pad. The units wish a 115 Vac electrical connection, a contribute water association and, if they have a water bleed-off mechanism to reduce mineral deposits, a method for water disposal.
The largest units have a cooling capacity of 3 tons, a contribute air flow of 1,400+ cubic feet per dinky and consume colse to 3 gallons of water per hour. This is sufficient cooling capacity for up to 1,700 quadrate feet of living space.
Since a two stage volatile cooler brings outdoor air into the home at a relatively high rate and doesn't recycle indoor air, unavoidable air pressure builds up inside the home. In order for the ideas to function effectively, the pressure must be relieved by occasion a few windows a merge of inches, or installing an exhaust duct or pressure operated damper in the attic or an covering wall.
According to the American society of Heating and Engineers (Ashrae), two-stage volatile coolers can reduce power consumption by 60 to 75 percent over accepted air conditioning systems.
Coincidently, I found a study by the department of power simulating the yearly power consumption of separate 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 volatile cooler.
According to the study, the air conditioner consumed 3248 kWh (kilowatt hours) of electricity during the cooling season. Using the mean California sell electric rate (2007) of .1435 per kWh, the resulting cost is 6.
By comparison, the two stage volatile cooler consumed 667 kWh of electricity for a seasonal cooling bill of , or 79% less than the air conditioner.
The new two stage volatile coolers have successfully taken the "swamp" out of swamp cooler but may face problems overcoming the image of its less comfortable predecessor; especially in light of a ,000 price tag.
However, based on the power cost comparison above, without taking into catalogue future rate increases, a two stage cooler would pay for itself in less than 8 years while interesting 79% less fossil fuel.
Two Stage evaporative Coolers Take the "Swamp" Out of Swamp Cooler
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