Don’t Install an Attic Fan If You Have Central AC
LESLIE: Alright. Now I’ve got Chris in Illinois on the line who’s dealing with a ventilation issue. Welcome, Chris.
CHRIS: Well, on a previous show, I heard that – this one lady asking about how to keep her third floor from being so hot.
CHRIS: And you had said make sure they have proper ventilation and gable vents and ridge vent.
TOM: Soffit vents and ridge vents.
CHRIS: Soffit vents and ridge vent, of course.
TOM: OK. Right.
CHRIS: And what about installing a thermostatically-controlled power vent to help that in the summer months keep that heat out?
TOM: Right. Only if you do not have central air conditioning is that a good idea and here’s why, Chris. If you use an attic fan – that’s what you’re talking about. If you use an attic fan and it’s on a thermostat so it only comes on when it gets, say, over 100 degrees up there, if you have central air conditioning, it will pull so much air out of that attic that it depressurizes and then reaches down through all the little cracks and crevices in the walls around pipes and around molding and where wires come through. And it’s actually been shown to steal air-conditioned air from the interior space.
So using the attic fan in the summertime, when you have central air, causes you to run more air conditioning, not less, because it’ll actually pull some of that air-conditioned air up into the attic. So if you don’t have air conditioning, I think – and power ventilator – an attic fan is a fine thing to do. If you do have air conditioning – central air – I would not use it; I would stick strictly with passive ventilation. Ridge and soffit vents are best.
CHRIS: Alright. Well, great. That answers everything.
TOM: Alright, Chris. Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.