Typically, the fan resides in the ceiling, with some sort of mechanism to seal off the attic from the main part of the house when the fan is off.
I use Tamarak brand. A little expensive, but quiet, subtle and the seal is motorized and seals well.
However, I had to modify it. The problem was caused by a poor seal between the attic and the house. The fan would pressurize the attic and instead of blowing air out the gable-end vents, it would blow dusty attic air into the house – through lighting fixtures, vents and such.
I ran it for 5 minutes before I decided it would not work. I smelled the attic air in the living room and, being sensitive to dust, took measures.
So, I kept the opening in the ceiling, with the seal in place, and removed the fans. I put the fans right at the gable end, so it pulls from the attic, which pulls from the house – then blows it straight outside. I think I lose efficiency this way, but I don’t blow attic dust into the bedroom.
In the recent remodel, added two fans on the side for more power. It works fine. I grew up in Tucson so I don’t feel the need for AC with these fans in place.
I know friends who spend $11K on their AC. Not for me. Not in SD. Maybe inland, it is needed, but we are in a breezy part of Clairemont.
