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Solar powered attic fans

Old 08-19-2019, 09:48 AM
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Default Solar powered attic fans

My 30 year shingles (IKO) seemed to have lasted about 18 years. So as I plan the new roof, we are thinking of adding some Solar Powered Fans to ventilate the Attic, Seems like a good time to do so. We have a great Southern Exposure that will put sun on the panels most all day.
The floor space of the attic is only 1100 Sq Ft. with a 9/12 Pitch. There are many makes, models, styles, etc of these fans.. We were hoping the THT Community would have some good information! Would also like comments on 30 Year Shingle brands. IKO was NOT good in our 18 year test. Was thinking GAF this time?? THX for any input!
Old 08-19-2019, 09:54 AM
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Not a roofer but my understanding is passive ventilation is the preferred method.
Old 08-19-2019, 10:25 AM
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If you put a turbine vent up there natural convection should cause it to turn and thus ventilated the attic space.
Old 08-19-2019, 10:29 AM
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Originally Posted by pizzacutter View Post
My 30 year shingles (IKO) seemed to have lasted about 18 years. So as I plan the new roof, we are thinking of adding some Solar Powered Fans to ventilate the Attic, Seems like a good time to do so. We have a great Southern Exposure that will put sun on the panels most all day.
The floor space of the attic is only 1100 Sq Ft. with a 9/12 Pitch. There are many makes, models, styles, etc of these fans.. We were hoping the THT Community would have some good information! Would also like comments on 30 Year Shingle brands. IKO was NOT good in our 18 year test. Was thinking GAF this time?? THX for any input!
Your shingles are not lasting because in Large part they are IKO shingles!!!!!!!!! Try filling a warranty claim on them.......you'll be lucky after they pro rate them you get one bundle in compensation for their shitty shingles that they say are at fault. I will NEVER buy their shingles again!
Old 08-19-2019, 10:57 AM
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My brother the electrician has his power bill down to about 90 bucks a month. That's a 2,000 sq ft house in Florida with 2 teenage kids.

he did his own solar setup along with a bunch of other stuff. An attic fan was one thing he did.
Old 08-19-2019, 04:39 PM
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If the roof was improperly ventilated no shingle would have lasted.

Do you currently have unblocked soffit venting? To vent air out you'll need to pull some in. A ridge vent will work fine passively if you have enough linear feet or ridge and if installed correctly has little chance of leaking. But you must have intake air in the soffits. I have seen a newer product that goes under the first row of shingles. Not sure if I am a fan, perhaps someone else can chime in on that.

We used Owens Corning shingles for most of the houses we built.

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Old 08-19-2019, 04:52 PM
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Attic breeze is my preferred if using active ventilation.
Old 08-19-2019, 05:01 PM
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IKO Shingles SUCK-A-Mundo!! I only got 14 out of mine. Didn't help that the installer barely put enough nails in them to boot! A Nor'easter blew some off so I took the opportunity to replace the whole roof - went with Owens Corning too.
Old 08-20-2019, 07:14 AM
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florida power and light used to say electric powered attic/roof fans were a money loser.

solar powered, dont know
Old 08-20-2019, 08:50 AM
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My current set up has soffit vents running down both eves and a ridge vent down about 90% of the entire ridge. So I think it is properly vented, but it still gets hot as hell up there in July/August. Maybe a solar fan (or 2) wont help with the extreme temperatures? If not, I don't want to waste time or money, just thinking this is a good time. So I guess my question is:: Will a Solar Fan Lower temperatures in the attic when it is 90 degrees plus outside?? As always, thx for input
Old 08-20-2019, 09:08 AM
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I don't think it will lower the temperature in the attic but I would be installing them just to get some air circulating.
Old 08-20-2019, 09:37 AM
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I don't know how they couldn't lower the attic temperatures. The ridge and soffit vents are to control the amount of MOISTURE in the attic, not really to do anything to cool the attic. If you increase the flow of air through the attic, it would have to lower the temperature closer to ambient outdoor air temperature.

How much would depend on how much airflow you're causing vs hot much heating is taking place. I haven't done any calculations to see how much CFM you'd need to move to make an appreciable difference, but someone probably has.
Old 09-04-2019, 08:09 AM
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TTT, thx for all comments. I am getting close to starting job. Will post what products we use
Old 09-04-2019, 09:13 AM
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Originally Posted by km1125 View Post
The ridge and soffit vents are to control the amount of MOISTURE in the attic, not really to do anything to cool the attic.
How do you think they accomplish that? Through the movement of air.

On a simple roof like that, if you have properly sized and unobstructed soffit and ridge vents, there is not much to be gained by adding a fan. Adding a fan may actually increase the temp of your roof surface (when thinking of shingle life, that is what matters, not attic air temp) in spots and make the problem worse if not thought of as part of a whole attic ventilation strategy. Natural convection currents should create the proper flow across the underside of the sheathing and keep it as cool as it's going to get.

My free internet warrior advice is to make sure you have properly sized and unobstructed vents, and use a better shingle.


Old 09-04-2019, 09:49 AM
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36 Watt Commercial Solar...

This is what i got to replace an electric attic fan that wasn't working when i moved into my new house. Has made a big difference even on the 2nd floor, used to get pretty warm from the attic heat in the summer. I should have checked temps before and after install. It moves a good amount of air and is pretty easy to install. Only thing that sucked is I have a good amount of pitch on my roof like yours and was a little sketchy just keeping my footing putting it in.
Old 09-04-2019, 09:55 AM
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Certainteed or GAF is what I would use on the roofing material. I’d use the Ice/water and the synthetic felt they sell instead of regular felt.
Old 09-04-2019, 10:09 AM
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Originally Posted by pizzacutter View Post
My 30 year shingles (IKO) seemed to have lasted about 18 years. So as I plan the new roof, we are thinking of adding some Solar Powered Fans to ventilate the Attic, Seems like a good time to do so. We have a great Southern Exposure that will put sun on the panels most all day.
The floor space of the attic is only 1100 Sq Ft. with a 9/12 Pitch. There are many makes, models, styles, etc of these fans.. We were hoping the THT Community would have some good information! Would also like comments on 30 Year Shingle brands. IKO was NOT good in our 18 year test. Was thinking GAF this time?? THX for any input!
My understanding is that Attics exhaust fans are a bad idea because it changes the pressure between your AC house and the Attic space allowing for the air between the to separate systems to come through.

https://www.greenbuildingadvisor.com...itive-pressure

Last edited by alfnator; 09-04-2019 at 10:38 AM.
Old 09-04-2019, 02:19 PM
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When I re-shingled a house about 8 years ago, the company I chose had bundled a pair of solar fans into their already low quote. I said sure, figuring it was a gimmick.

I was shocked when I saw them, they were much bigger than I expected (maybe 18-24” around?) and while I didn’t live there long enough to have a scientific test - they both pumped out hot air you could easily feel while standing up there, I don’t know how it wouldn’t have made a difference. I think the fans had a list price in the $200 range. Definitely didn’t move so much air that they’d be creating a pressure differential but a steady flow of output.
Old 09-04-2019, 02:41 PM
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As far as lowering the power bill, I’d say it mostly depends on how well the attic is insulated. An attic with less insulation will benefit from air movement more so than a insulated attic. You’d have to get an awful lot of suction to cause your A/C to be sucked into the attic. Make sure your ducts are sealed well with mastic.

I just installed a solar powered dc cooling fan in the gable end of the house about a month ago. I have the panel mounted to where it will turn on around noon and run till the sun is down. Cost was maybe 50$ and it seems to keep the attic a little cooler in the blazing heat of the day, plus it keeps air moving. The house is nearly 100yrs old so insulation could be better to say the least. I’d say it’s worth it. As far as roofing material my favorite shingle is metal
Old 09-06-2019, 08:56 AM
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All great comments. The other thing I will investigate is spray on foam on the underside of the roof sheathing (in the attic) I have heard a lot of good about how that keeps attic temperatures down. It also strengthens the roof system by tying togehether the sheathing and rafters. That is a consideration as we are only 2 miles to Ocean-Front. Thx again for comments

BTW the fans that I have narrowed down so far are I-Living, Natural Light, Attic-Breeze, Remington,,, I like all these .. they are running between $350 & $550 … for the size I need

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