Thread: Solar Attic Fan
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Old 07-04-2012, 09:26 PM
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Quote:
Originally Posted by faithfulfrank View Post
A typical Attic is designed to pull cooler air passively from the soffits up through either a ridge vent or non-powered roof vents placed close to the ridge. This natural convection works well as long as you have the proper amount of ventilation.
Agree

Quote:
When you install a powered vent, it will take air from the least resistance. This usually is from the already installed ridge vent....thus "short circuiting" the natural convection from the soffits and leaving much of the attic with less air movement.
Not saying you're wrong just want to understand, there is more sq" of ventilation area in the soffits than the ridge vents, I think you agree.
Therefore, the least resistance in not the ridge but the soffit, does that make sense?

Quote:
Worse, sometimes they can produce negative pressure from openings in the living space ceiling and draw CONDITIONED air from the interior of the house into the attic
But those openings would have to have less resistance than then the ridge or soffit I would think.

Quote:
This negative pressure could also cause backdrafting from a water heater and put carbon monoxide into the house.
That's a stretch, how about using the right size not oversized fan in the first place. Moreover, with that theory those same fumes would exhaust out thu the attic.

Quote:
Studies have shown that powered ventilation may lower the temps up by the ridge by about 10 degrees, but the temps right above the insulation show a drop of less then 5 degrees.
Can you please point me to those?

Frank, understand I think the radiant barriers are my first choice, my second choice is to seal all the duct work in the attic, than a fan if that doesn't cut it.

Great to have a professional contribute but some of us like to dig deep into silly things like this
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