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FRIDAY, AUGUST 3, 2007
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Solar attic fan will keep down cooling bills

Dear Jim: My roof gets direct sun from noon through late afternoon and I imagine this is making the house hotter. I have some attic ventilation, but I thought about installing a solar attic vent fan. Will it do much? Mike H.

Dear Mike: It is not just your imagination the hot roof/attic is making your house warmer. It can also increase your electric bills and reduce the life of the roofing materials. Touch the ceiling under the attic floor and I bet it feels quite warm. Standard insulation on the attic floor is not particularly effective at blocking radiant heat from a hot roof.

You have two basic ventilation options to keep the attic cooler.

One is increasing the amount of natural ventilation area. This involves installing cool air inlet vents in the soffits and hot air outlet vents along or near the ridge (peak) of the roof. With no fan to create air flow, much vent area is needed.

The other option is a power ventilator for the attic. Since your primary concern is for summer cooling, installing solar-powered attic fans can be effective. What is nice about these is, on the sunniest days when the most ventilation is needed, these fans, powered by the sun, run very fast. On cool, cloudy days, less electricity is produced and they run slower.

As with any outlet vent, a solar attic fan should be located near the peak of the roof. The diameter of most solar attic fans is 12 or 16 inches, so you should not have a problem finding a location near the roof peak. It still is important to install the cool air inlet vents in the soffits to allow for maximum ventilation through the solar attic fan.

Solar panel

Most solar attic fans include a built-in solar panel that produces about 10 to 12 watts of electric power providing a maximum of about 850 cubic feet per minute of air flow. A typical 10-watt solar panel is slightly smaller than the top area of the fan.

Some of the larger 16-inch fans can handle a larger 20-watt solar panel and produce up to 1,200 cfm of ventilation.

It is not difficult to install a solar attic vent fan. Saw a 12- or 16-inch hole in the roof. All solar attic fans have built-in flashing. Weave the flashing under the existing shingles and nail or screw the fan in place. Since it is solar-powered, it requires no 120-volt electric wiring.

If you want to mount the vent fan on a shady side of the roof for aesthetic reasons, select a model with a remote solar panel. The small solar panel can be mounted on the sunny side of the roof with a small wire leading to the fan.

This remote design is also effective if a side of your roof does not face south or southwest. Another fan design has a hinged solar panel that can be tilted up to face the sun more directly.

The following companies offer solar attic fans: Marathon Roofing Products, (800) 828-8424, www.marathondrains.com; Nulight Solutions, (877) 326-2884, www.fan-attic.com; RE Williams /Natural Light, (888) 845-6597, www.rewci.net; Solar Dynamics, (800) 775-2134, www.solardynamicsinc.com; and Solatube, (888) 765-2882, www.solatube.com.

Energy Star for plumbing?

Dear Jim: I am remodeling my bathroom and I want water-saving fixtures. I installed efficient Energy Star labeled products when I did the kitchen. Is there anything similar to Energy Star for plumbing items? Kari H.

Dear Kari: There now is a labeling system similar to Energy Star for plumbing fixtures. It can be found at www.epa.gov /watersense. It includes useful information for conserving water and lists products that meet its requirements.

Send inquiries to James Dulley, The Decatur Daily, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www.dulley.com.

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