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Is it worth the savings in energy cost to install a gable fan for my attic?

I went up there and to install a bath fan and it was ridiculously hot. There are currently grated vents at each end of the attic, and grated vents about every 10-15 feet under the gutters. There is also about 1 ft of blown in insulation. I was thinking of installing a gable fan connected to a thermostat. If I were to do this, at what temperature should I set the thermostat? And should the fan blow air inward or outward? I live in Louisville, KY.

Gable vents are definitely worth the money but even more important are ridge vents (near the peak of the roof) There should be at least one for every 10 linear feet of roof. Ridge vents let hot air out like gable fans but don't require any electricity and also allow circulation year round which will prevent moisture build-up in the attic (bad for lumber and insulation).

The fan should blow out – you want the cool air coming in through the soffit vents (near gutters). The fan manufacture should have recommendations for temperature settings.

Be sure to have a qualified roofer do the ridge vent install – you don't want any leaks!

Hope that helps.

Mike
 

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appliance, HVAC Technician - January 3, 2009

Install as soon asyou can. Getting rid of theheat will greatly increase the life of your roof.
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Cory - January 3, 2009

Gable vents are definitely worth the money but even more important are ridge vents (near the peak of the roof) There should be at least one for every 10 linear feet of roof. Ridge vents let hot air out like gable fans but don't require any electricity and also allow circulation year round which will prevent moisture build-up in the attic (bad for lumber and insulation).

The fan should blow out – you want the cool air coming in through the soffit vents (near gutters). The fan manufacture should have recommendations for temperature settings.

Be sure to have a qualified roofer do the ridge vent install – you don't want any leaks!

Hope that helps.
References :

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paul h - January 3, 2009

Definitely go with a powered vent fan or look into some solar powered ones—no electrical costs.
http://www.solarroofvent.com/
http://www.solardynamicsinc.com/
Powered vent fans help keep the attic and ceiling temps lower to reduce the need for a/c use…I would recommend adding another 8-10 inches of blown insulation as well. A contractor or Home Depot type store should have info on insulation thickness factors and probably something on powered vent fans as well. Vent fans should exhaust any hot air from the attic to outside and you can adjust when they kick on—probably would want it on at a temp close to 80 degrees or so.. Whole house fans are another option to reduce a/c use on certain days depending on how the house is situated and other factors.
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Mr. Kool - January 3, 2009

I install several every year, and I'd put in the biggest fan I could find, in fact, in my house, I installed a condenser (outdoor a/c unit) fan in my gable, because they are much more powerful and run on 220, instead of 110, less electricity.
Forget the solar powered fans, not worth the effort.
If you install a gable fan, close off the area around the fan and the closest vents, so it will pull air from the farthest point and pull out the most heat.
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HVAC company owner

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