Find out whether it is economical to run an attic fan. Attic fans are not recommended if you have central air conditioning because when you turn the fan on in the summer, it depressurizes the attic but also reaches down into your house and starts drawing off air-conditioned air, effectively driving up your cooling costs. Instead of installing a fan, just make sure your attic is well-ventilated using passive vents. The most preferred are ridge vents and soffit vents.
LESLIE: Now we’ve got Doug from Rhode Island who’s got a question about an attic fan . How can we help you with that?
DOUG: Somebody gave me a new, 15-inch attic fan. And I’m considering installing it but I also wondered, the electricity I’m going to use to run the fan, it’s maybe a wash. I don’t know. In other words, is it economical to run this attic fan?
TOM: Yeah. I’ll tell you what, I don’t have a good opinion of attic fans because what we have found – do you have central air conditioning in your house?
TOM: Well, what’s been found is that if you turn the attic fan  on in the summertime, that it depressurizes the attic but it doesn’t stop there. It’ll reach down through the insulation – it’ll find all the little cracks and crevices in that ceiling space – and it’ll reach down into your house and it will start drawing off air-conditioned air and actually drive up your cooling costs.
So, I’m glad you didn’t have to pay for the attic fan but I wouldn’t put it in, if it was me. I would just make sure that my attic was well-ventilated, using passive vents. The most preferred are ridge vents and soffit vents .
DOUG: Yeah, I’m trying – I have sufficient vents.
TOM: Yeah. Then I don’t think you should put it in. I don’t think it’s going to help you and it could potentially hurt you.
DOUG: OK. No, I understand exactly what you’re saying.
DOUG: Thank you for your time.
TOM: You’re welcome. Good luck with that project. Thanks so much for calling us at 888-MONEY-PIT.