November 23, 2024
ANALYSIS

Solar-powered fan removes excess heat from attic, ceiling

Dear Jim: Our house feels warm even with the air conditioner running. The temperature seems to be low enough for comfort. Could the heat be coming from the attic? Will solar-powered attic fans help much? – Caroline J.

Dear Caroline: Your situation is not uncommon. My guess is, if you put your hand on the ceiling, it will feel warm. Even though the room air is cool, you feel warm from radiant heat transfer. It is the reverse of when you feel chilly during winter when you sit near an outside wall or window.

In addition to your feeling warm, your central air conditioner is running overtime to remove this excess radiant heat coming down through the ceiling from a hot attic. To make matters worse, you often have to set the thermostat lower to stay comfortable and your electric bills go even higher.

A solar-powered attic exhaust fan is a good choice to help keep your attic and roof, and thus the ceiling below, cooler. A solar-powered fan is an ideal match for your needs because as the sun is more intense on the roof, it also creates more free solar electricity so the fan runs faster.

Another monetary benefit of keeping your attic and roof cooler is an extended life for the shingles. High heat hastens the degradation of just about any material used in a house. By placing one or two solar fans up near the peak of the roof, the hottest air will be drawn out of the attic.

You don’t have to be an electrician to install a solar attic fan. The solar panel is built into the top of the fan and it produces free electricity. To install one, you just have to saw a hole with a 12-inch diameter in the roof and loosen a few shingles. Nail the fan in place and replace the shingles. Curb-mounted models are also available for flat and tile roofs.

If the area of your roof where you want to install the fan does not face the sun directly, you can install a remote fan. It uses a similar fan, but it has a separate solar panel. The 1-foot square solar panel, on an adjustable stand, can be mounted up to 20 feet away in a sunny location.

The remote panel may be the most efficient option because the small solar panel stays cooler than when it is built into the top of the fan. The hotter solar cells get, the less free electricity they produce. The small wire, which carries the safe 12 volts, can barely be seen on the roof. You may also consider attaching two solar panels to one fan for extra cooling.

Another installation option to consider is a built-in design with a hinged solar panel. It can be tilted up from the fan top to face the sun more directly. Also, with the solar panel tilted upward, even at a slight angle, air flows around it to keep it cooler and keep its efficiency high.

Write for Update Bulletin No. 987, a buyer’s guide of 11 solar-powered and turbine attic fan manufacturers listing air flow ratings, watts, sizes, features, prices, and a sizing chart. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH 45244., or, instantly download it at www.dulley.com.


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