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wrote:
wrote:

One other thing not mentioned yet is thermostatically-controlled attic
ventilation. Works great for me in SW CT, so I don't know how you
survive without one from June to October in TX.

Anything you can do with a fan can be done with soffit and gable vents,

I think that's an overstatement.

with no electrical energy. With A ft^2 of vent area at top and bottom
and an H' height diff and dT (F) temp diff, cfm = 16.6Asqrt(HdT).

Please point us to a derivation of your equation so we can consider
its assumptions.

For example, an attic with 2 2'x2' gable vents and equal soffit vent area
and H = 8' and dT = 10 F would have 16.6x2x2x2sqrt(8x10) = 1188 cfm of
airflow. I'd close the gable vents in wintertime with plywood doors
hinged at the top.

I know that my attic has vents similar to your example, and that its
temperature was well in excess of 120 degrees before adding a fan.
With an outdoor temperature of 90 degrees, I should have had a near
hurricane going on up there according to your calculation, but didn't.

Nick

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