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solar attic fan vs roof vents

10 years ago

Hi,

We have bought a solar attic fan at a good price from costco.

Our architect/contractor mentioned that the attic fan can be used in lieu of many roof vents (which can make the roof look ugly), depending on the size of the roof.

Is that possible? Is there a simple calculation that be done to determine this?

Also, i have heard recommendation for a ridge vent instead of multiple smaller roof vents? Is that better than either solution?

Thanks a lot.

Comments (11)

  • 10 years ago

    It would help if you told us the climate, if the ceiling below is well sealed, how the attic is used and if there are any HVAC ducts or equipment in the attic.

    To go through all the different possibilities would be a real chore so I will wait for your response.

    For now I will say that there are very few situations where a mechanical exhaust fan in an attic is a better idea than eave and ridge vents.

  • 10 years ago

    I agree with Renovator8.
    do a site search for threads about pav's
    (powered attic ventilators)

    did you save your reciept?

    best of luck.

  • 10 years ago

    Thanks guys.
    I did read the other threads about pav's. Both positives and negatives.

    More details about our project:

    its california central coast weather. Attic is ok-sealed. Attic is used to install furnace and will have ducts going around. There are sufficient soffit vents that it should be sufficient to provide air for any powered ventilation.

    Hope this helps.

  • 10 years ago

    I have no experience with such a mild climate but for more severe climates the current expert wisdom is to include the attic space in the conditioned space of the house by insulating the roof above the attic, leaving an air space between the insulation and the roof deck and providing code compliant eave and ridge vents.

    Here is a link that might be useful: current wisdom

  • 10 years ago

    Good thing it's Costco. Return it and do the sealed attic bit.

  • 10 years ago

    In my opinion it is always better to use a non mechanical solution when possible. Ridge vents are the best but hip roofs may limit the amount that can be used.

    Here is a manufactures calculator page

    Here is a link that might be useful: calculator

  • 10 years ago

    @hollysprings yes :) best part about costco.

    @ChrisStewart are ridge vents easy to install? Our project, the framing is done and the plywood has already been installed on the roof.

  • 10 years ago

    Ridge vents should be easy to install if they haven't put on the shingles. In most cases they just cut a slot in the sheathing on both sides next to the ridge and the vent sits on top of the slot.

    Bruce

  • 10 years ago

    I haven't found a building scientist or researcher who thinks attic fans, solar powered or not, are useful. See, for instance, Energy Star andDr. Joseph Lstiburek.

    Properly done, sealed or vented attics work well.

    This post was edited by worthy on Tue, Nov 19, 13 at 21:09

  • 10 years ago

    If this is an open attic the roof framing should not be an issue.

    It might be necessary to cut back the sheathing at the ridge before installing the ridge vent.

  • 10 years ago

    The biggest danger besides wasted money having zero effect is making things worse by sucking the conditioned air of the house into the vented attic.

    A MUCH better return on investment would be going into the attic, pealing back all the insulation, air sealing the ceiling plane and adding more insulation once finished. Air sealing and blown cellulose is dirt cheap compared to years worth of wasted energy, even in most mild climates.