Yes, you don't want it to vent outside, you want it to vent into the attic, your Attic is most likely 110-130 degrees on a hot day, that radiates down into your house, so when you are sucking cool air into your house it's venting only 70-80 degree air into the attic effectivly cooling the attic as well as the attic should have some vents to push the hot air out. So it's cooling the house and attic at the same time. Trust me they are fucking awesome in the fall. In the summer if it falls below 70 at night, I will open some windows and suck some air in, just to cool the attic.