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  • natel
    started a topic Solar Attic Fans

    Solar Attic Fans

    I'm looking into solar attic fans. My first question is why are all the solar attic fans such low wattage? My second question is do they make them that are gable mount so that I don't have to cut a big hole in my roof? Maybe an even better question is how much do attic fans help, if they even help at all?

  • Shockah
    replied
    0420041001.jpg

    Cheap Attic, Bilge, or Compartment Fan.

    30watt Bilge Blower/50watt Panel... nothing in between.
    Volts as high as 16.5
    Blower begins blowing at >3v.

    Leave a comment:


  • russ
    replied
    Originally posted by inetdog View Post
    OK, somebody got careless with the Moderator editing tool and inserted someone else's words in the above post under my name. Whatever happened, the above reply to Naptown did not come from me.
    I doubt Mike did it and I didn't so careful with the finger pointing - these forum platforms are generic I suppose - easy for someone to play games.

    Leave a comment:


  • inetdog
    replied
    Originally posted by inetdog View Post
    The use I have in mind is actually for a garage which has only small passive louvered gable vents. In the summer it gets really hot and makes the workshop area almost unusable.
    I can put money into radiant barrier insulation on the inside of the uninsulated open truss roof, or powered gable fans, or something solar. Any thoughts on the respective merits of each? (Almost forgot: Currently there are no floor level or other vents in the walls, but I do have screened windows on the shaded side that can be opened if I remember.)

    (I have seen discussions of line-powered fans that say the Home Depot type will only last a few years, but touting a $400 line-powered German model. Are there lifetime issues with the solar-powered DC motors?)

    The summer outside temperature does not get much above 100 on the worst days, but the inside of the garage can easily get 20 degrees or more hotter at head level and intolerable up near the roof.

    OK, somebody got careless with the Moderator editing tool and inserted someone else's words in the above post under my name. Whatever happened, the above reply to Naptown did not come from me.

    Leave a comment:


  • stev
    replied
    I want to put a box fan in the gable end of my house.
    I have a 105 watt solar panel to run it.
    A new Grape Solar fab 8 from Home Depot.
    Any 12 volt box fans? Any ideas?
    Good idea on the radiator fan from the auto junk yard.

    Leave a comment:


  • Wy_White_Wolf
    replied
    I took an old cooling fan and it's relay out of a junker car. Wired the relay to a snap switch to acitvate and a 100W solar panel. Turns on about 85F and off at 75F. Works great and was alot cheaper than the premade units. I only expected it to last a year but it's starting it's 3rd year and running strong.

    WWW

    Leave a comment:


  • Volusiano
    replied
    Originally posted by tonystewart View Post
    I have 3 solar fans from Home Depot, mounted and sealed to the roof under 3 of the 5 "metro" metal roof vents. I have a continuous soffit with ducts between trusses.
    I attached 60 watt panels to each of them. They spin fast.
    My attic has radiant barrier on top of the fiberglass insulation and my attic temperature has lowered substantially.
    135 degrees was common in the summer, now it doesn't exceed 105.
    They have been in operation for over 14 months, I feel they will pay for themselves over time.

    I'm in South Florida, Your mileage may vary
    How are you able to attribute how much of the lowered attic temperature to the radiant barrier and how much due to the solar fans? I would guess that much of it is due to the radiant barrier.

    Leave a comment:


  • inetdog
    replied
    Originally posted by LucMan View Post
    They are not for everyone! Most likely no roof penetrations in hurricane country are acceptable.
    They work great here in NY.
    Interesting.
    I have no doubt that they work great in the sense that they can be seen spinning.
    But there have also been some credible studies that purport to show that in terms of actual air movement, a pivoted fixed vent (keeping the horizontal opening downwind) without the obstruction inherent in the whirlybird actually does a much better job at less cost and with smaller roof openings.
    If there is little wind, then the restriction to air movement that the whirlybird provides makes the ventilation much worse than an open vent (with a rain cap).

    Leave a comment:


  • russ
    replied
    Seems to me like a radiant barrier and a air mover fan is your best bet.

    Leave a comment:


  • inetdog
    replied
    How about vents for a detached garage?

    Originally posted by Naptown View Post
    how much they help is dependent on how the attic is ventilated now. But generally they are not worth much.
    The use I have in mind is actually for a garage which has only small passive louvered gable vents. In the summer it gets really hot and makes the workshop area almost unusable.
    I can put money into radiant barrier insulation on the inside of the uninsulated open truss roof, or powered gable fans, or something solar. Any thoughts on the respective merits of each? (Almost forgot: Currently there are no floor level or other vents in the walls, but I do have screened windows on the shaded side that can be opened if I remember.)

    (I have seen discussions of line-powered fans that say the Home Depot type will only last a few years, but touting a $400 line-powered German model. Are there lifetime issues with the solar-powered DC motors?)

    The summer outside temperature does not get much above 100 on the worst days, but the inside of the garage can easily get 20 degrees or more hotter at head level and intolerable up near the roof.

    Leave a comment:


  • tonystewart
    replied
    Originally posted by LucMan View Post
    They are not for everyone! Most likely no roof penetrations in hurricane country are acceptable.
    They work great here in NY.
    Did your area receive extensive wind or water damage from the last hurricane?

    Leave a comment:


  • LucMan
    replied
    Originally posted by tonystewart View Post
    Do you know what we call those in South Florida? Hurricane openings! The new roofing codes won't even allow them to be installed. No roofer will touch those in South Florida.
    They are not for everyone! Most likely no roof penetrations in hurricane country are acceptable.
    They work great here in NY.

    Leave a comment:


  • tonystewart
    replied
    Originally posted by LucMan View Post
    Take a look at the Whirlybird attic ventilators, just a slight breeze and they spin removing humidity and hot air from the attic.
    http://www.ehelpfultips.com/do_whirl...vents_work.htm
    Do you know what we call those in South Florida? Hurricane openings! The new roofing codes won't even allow them to be installed. No roofer will touch those in South Florida.

    Leave a comment:


  • LucMan
    replied
    Take a look at the Whirlybird attic ventilators, just a slight breeze and they spin removing humidity and hot air from the attic.
    http://www.ehelpfultips.com/do_whirl...vents_work.htm

    Leave a comment:


  • tonystewart
    replied
    Originally posted by natel View Post
    If I have a single 120w solar panel, can I safely power two of these fans?
    Yes, no, maybe, depends on voltage, amperage, etc. Kinda vague

    Leave a comment:

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