DIYbanter - View Single Post

wrote:

wrote:

Edwin Pawlowski wrote:

Ideal is both.

If you have no AC, go with the whole house fan. The advantage is that it
will draw in cooler air from outside and push the hot air out of the attic.
The disadvantage is that on a very hot day, it will draw in the hot outside
air and replace what may be cooler inside. That is when the power vent in
the attic is best.

If you do add AC, you don't want to use a while house fan at the same time.

Ditto that, but using the fan for double-duty. In my case, during the
day the power vent fan in the attic switches on around 100 deg. F, with
the attic sealed off from below.

Starting a power vent fan in the attic when it's only 100 degrees is a
waste. Attic insulation should be more than adequate to handle a 25
degree temp delta. What yo need the attic fan for is to keep it from
getting to 140. I have mine set to go on at about 110

FWIW, I have mine set to go on at 90, and I don't think that's a waste;
it can't keep up, so needs a head start -- any higher and the peak attic
temp gets too high. So the devil, as always, is in the details. If you
have a relatively small fan, as I do, having it come on early might make
a lot of sense.

When temps drop outside in the

evening, I open some windows at the (N) side of the house, farthest
from the door to the attic, and open that door, then drop the setting
on the fan t-stat. Soon, I'll just put in a manual switch in parallel
with the t-stat, or a timer.

J

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .