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| | | Although they're often confused, an attic fan (also called a roof fan or a PAV--a powered attic ventilator) isn't the same as a whole house fan. An attic fan runs during the day to reduce heat build-up by ventilating just the attic area. A whole house fan is used at night, reducing or eliminating the need for air conditioning by drawing cool air into the entire home and forcing hot air into the attic and out through the roof. | | |
| Typical costs: | - Prices for electric attic fan kits average $70 -$300, with operating costs of about $2 -$3 a month; a humidistat (which activates the fan if it senses excess moisture inside the attic) adds another $90 -$150. Solar-powered attic fans have zero operating costs and sell for $350 -$600 depending on capacity, manufacturer and optional features such as a thermostat, according to ToolBase.org. For professional installation of an attic fan, contractors generally charge $30 -$70 an hour; the total cost will vary depending on attic conditions and the complexity of the project.
- A whole house fan averages about $150 -$350 and costs about 1-5 cents per hour of use, compared to 17 cents - 20 cents an hour for air conditioning, according to the US Department of Energy. However, prices for larger whole house fans can go as high as $550, and many homes need added attic ventilation to let the hot air escape quickly. Coupled with professional installation services, this can bump the total cost to about $1,000 -$1,600.
What should be included: | - On a hot day, temperatures in an attic can climb as high as 150 degrees F; attic fans push out this overheated air. Attic fans can be installed through the roof or through a side wall of the attic. There is some potential for leakage after installing a roof-mounted attic fan, and in extreme cases an attic fan can bring noxious gasses back into the house. AskTheBuilder.com recommends against attic fans, while HomeVentilation.com provides strategies for mitigating potential problems for both attic and whole house fans, including installing both kinds of fans.
- Whole house fans are usually mounted in a central spot in an upstairs ceiling and vented into the attic. They work best in climates with relatively cool evenings, such as the Midwest or the northern half of the US; they don't work well in more tropical homes with air conditioning, because they can pump out the expensively cooled air.
- Better Homes and Gardens gives details instructions for adding an attic fan or installing a whole-house fan.
Shopping for an attic or whole house fan: | - Enter an attic size in the calculator provided by CSGNetwork.com to get estimates for the capacity needed for an attic fan.
- The US Department of Energy gives a simple formula for picking the right size for a whole house fan.
- One attic and whole-house fan manufacturers is Broan. Lowe's offers a limited selection of whole house fans.
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Article updated July 2007 |
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