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Thread: solar attic fan

  1. #1
    Join Date
    Sep 2004
    Location
    Fort Worth, Texas
    Posts
    586
    I was at Lowes today and saw a solar powered attic fan. 850cfm for 1200sqft. The vents I have now are those cheapo mushroom headed looking rascals. I live in Texas and my attic is hotter than Satan's armpit. What's the verdict. $368 a good investment or a waste?
    Installs, Changeouts, & Heat Stroke.....not necessarily in that order

  2. #2
    Join Date
    May 2006
    Location
    Winder, GA.
    Posts
    387
    In theory I believe so. Not past the test stage as of yet.

    Longevity is the main issue.

    Hell the conventinal would cost 150 to 200 hundred and you keep on paying day after day after day after day after day...gotta get back on my meds.

  3. #3
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,295
    Originally posted by rubberduck
    I live in Texas and my attic is hotter than Satan's armpit. What's the verdict. $368 a good investment or a waste?
    Can you translate that TX expression into
    a Real temperature?

    Are there any ducts in your attic?
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  4. #4
    Join Date
    Sep 2004
    Location
    Fort Worth, Texas
    Posts
    586
    I have flex in the attic.

    That would translate into triple digits with around 60% humidity.

    I am thinking that I am losing alot of cold air from the flex duct due to the warm temp in the attic.
    Installs, Changeouts, & Heat Stroke.....not necessarily in that order

  5. #5
    Join Date
    Nov 2005
    Location
    Northern VA
    Posts
    512
    Conventional attic power vents cost very little to operate and can move twice as much air as the solar fans. You will never make back the first cost difference with the solar unit. The exception might be if adding electric service to your attic would be expensive - if, say, the furnace circuit is the only one up there now. (Since that's a single-appliance circuit, you can't legally add anything else to it.)

    Solar - *might* mean you don't need a permit, or you might need a building/appliance permit. Permits for solar equipment are no-fee in many areas too. Note that despite the manufacturer's claims, this is still an electrical device and some jurisdictions might still want a "low voltage" electrical permit. Keep in mind that you will need to install two solar fans to move as much air as one conventional fan, and that solar fans don't work when the sun isn't shining.

    Conventional - you will almost definitely need an electrical permit, possibly in addition to the building/appliance permit. Add permit fees on top of the cost of providing a legal branch circuit to the fan. Often those costs will be minimal, sometimes they will be substantial. In most cases, the conventional fan will probably end up being cheaper - and it runs all the time when the attic's hot enough to need it, not just when there's direct sunlight available.

  6. #6
    Join Date
    Jul 2006
    Posts
    21
    Not to mention the proabable effects of even small hail on the solar pannels.

    If one of the goals is to remove humidity from the attic, snow or ice buildup would also be an issue in winter time.

  7. #7
    Join Date
    Jul 2005
    Posts
    435
    If you have an asphalt shingle roof, have a roofer come buy and install a full ridge vent along all your ridges
    (cobra etc.).
    These type of vents have proven to be the most effecient and if your soffit venting is adequate natural convection will force the hot air out!

  8. #8
    Join Date
    Jul 2006
    Posts
    21
    Yep - but I understand there are issues with getting enough ridge length for hip roofs, as well as draft-bypassing if you have multiple-level peaks. A draft can be created that makes the lower peak's ridge vent an intake and the upper ridge vent as the outlet - which can really cut down on the intake at the soffit level.

    Guess who's roof is both multi-peak and a hip roof? :(

  9. #9
    Join Date
    Jun 2004
    Location
    Dallas
    Posts
    179
    I was put off by the high cost also, until I found a solar fan for 50 at HD and a solar panel for 50 at HD (you can add more panels if you want more speed- nice feature)

    So for 100 I got a fan than runs for free, operates at a closer to proper speed (meaning any 120v fan pulled WAY too much- would have caused problems) and runs when the wind is not blowing- which often happens in the hottest parts of the day around here (DFW).

    Shop around some more- that price you found is way to high.

    Good luck.

  10. #10
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    be careful with ridge vents -- need to be baffeled--

    read -- lots of discussion last yr for turbine type & elec pwr vents --
    I have used both. My 120v fan over bdrm [3rd level] is 20+y/o, works fine -- runs when ODT =>85F & not hazy or cloudy -- 4-5h/da =$$0.05/da for elec.

    The current units, like most items now, are poorly made! My elec lasted 2wk from Lowes in 2000 = $100 -- fan shook loose from bracket & jammed = motor shot! then blowing rain came in since top hat was not large enuf. I had tin- knocker put a 1" skirt on hat to stop rain & now just let gravity remove air out of attic of 2nd level. --
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

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