DIYbanter - View Single Post

060621 1320 - posted:

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

So, if you have a fire in the attic, the fan will come on and make things
worse...