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Who was that looking for DC attic fan?

Discussion in 'Home Power and Microgeneration' started by GeekBoy, Apr 24, 2006.

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  1. GeekBoy

    GeekBoy Guest

    This week's Home Depot circular has an a solar powered attic fan for $168.
    Comes with 10 watt solar panel and available for either gable (item
    #607688) or roof mount (item # 607690).


    GB
     
  2. tom

    tom Guest

    for anyone considering Attic Fans, some reading material on the pro and con

    http://www.advancedenergy.org/buildings/knowledge_library/ventilation/attic_ventilation.html

    http://www.askthebuilder.com/236_Powered_Attic_Fans_-_Attic_Insulation_Facts.shtml

    I (like so many) have been running dual thermostatic attic fans (bought from Home
    Depot and Lowes) for 12 years, until I discovered that they indeed are worthless and
    just used more electricity
     
  3. GeekBoy

    GeekBoy Guest


    Umm,,,,I guess you did not read the post. I did write they are SOLAR POWERED
     
  4. JoeSP

    JoeSP Guest

    When I do the math, a 10 watt panel will provide enough energy to do
    precious little air movement. I would probably go with a whirlybird vent,
    backed up by a small duct-mounted AC fan, controlled by a two-stage
    thermostat. The first stage would open an electric damper in the duct,
    allowing the whirlybird fan to suck out the air. Then if the whirlybird fan
    on the roof isn't doing enough, or if there's no wind, the fan in the duct
    would kick in at the second stage of the thermostat. This way, you would get
    adequate and controlled airflow at minimal cost, utilizing the wind whenever
    possible.

    Solar energy is free, but expensive, and rarely worth the investment when
    grid power is available. Wind power is both cheap and free, but it's the
    least reliable source. I think the best choice is wind-driven ventilation
    with a grid power backup.
     
  5. mika

    mika Guest

    Umm... I guess you did not read the links... it does not matter (read the
    links and you will find out why)
     
  6. GeekBoy

    GeekBoy Guest

    The best thing I have seen is when a neighbor replaced his roof. He
    installed a small vent that ran the entire length of the very top arch of
    the roof. He also installed better vents at the bottom ridge. Since heat
    rises, I see this as causing a natural draft to bring in cool air from the
    outside.
     
  7. GeekBoy

    GeekBoy Guest


    No need to . He said it was wasting electricity.
    Can't waste what will not end for billions of years.
     
  8. tom

    tom Guest

    actually, read the links and you will find why you are running A/C even harder (=more
    electricity)

    this has nothing to do with solar
     
  9. JoeSP

    JoeSP Guest


    Seems to me, most attics are already vented in such a way. Passive
    ventilation from natural convection will still contain a fair amount of hot
    air in the attic at any given time. Powered ventilation will reduce the
    temperature in the enclosure in proportion to the volume of air movement.
    That's why computer cases have fans and not just vent holes.

    The trick is to close it when the weather is cold. It's good to retain heat
    in this era of escalating energy costs. Some people I know draw heated air
    down from the attic in the winter to feed through the furnace and save a
    little on heating costs.
     
  10. GeekBoy

    GeekBoy Guest

    No matter what, most heat entering the home enters from the ceiling that is
    being stored in the attic.
     
  11. surfnturf

    surfnturf Guest

    Joe,
    Good attic ventilation is even more important in cold weather. Moisture from
    condensation must be allowed to escape, or the area will become a breeding
    ground for mould and fungus. Agree heartily with the rest of your post.
    Cheers,
    surfnturf
     
  12. GeekBoy

    GeekBoy Guest

    I agree since air will act live electicity and seed the path of least
    resistance.
    Those who believe in it apparantly cannot think on their own and hold every
    article on the net as absolute truth.
     
  13. have you thought of a solar chimney?
    Solar Chimneys: Where prevailing breezes are not dependable enough to rely
    on wind-induced ventilation and where keeping indoor temperature
    sufficiently above outdoor temperature to drive buoyant flow would be
    unacceptably warm, a solar chimney may be an effective solution. The chimney
    is isolated from the occupied space and can be heated as much as possible by
    the sun or other means. Air is simply exhausted out the top of the chimney
    creating a suction at the bottom which is used to extract stale air.


    http://131.251.21.249/local/natvent/NaturalVentilationInBuildings.htm
     
  14. thats true but an additional solar chimney may be a replacement option
    instead of the powered atic fan this person was looking for.
     
  15. Robert Megee

    Robert Megee Guest

    This week's Home Depot circular has an a solar powered attic fan for $168.
    That may have been me. I already have a 45 watt solar panel and was
    looking for just the fan. Most places I looked wanted to sell the
    entire system not just the fan. I did try a dc fan that Home Depot
    sold. The first one ran for all of 30 seconds before it died. It's
    replacement was so damaged that it wouldn't work at all. At least
    they gave me my money back. They were quite inexpensive and I know
    why now.
    I did find a fan. A 20 watt fan. I just hooked it up late yesterday.
    I don't have any temp measurements yet but the difference in my
    attic was very noticable. And that was at 6pm a bit past the peak
    output. As for its affect on the cooling of my house, I suppose the
    insulation between my living space and the attic should slow down
    heat transfer but it's still there. And it's not even really hot here
    in Texas yet.

    Robert
     
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