Find out why you should not get an attic fan if you have central air conditioning. Also learn why you should install ridge and soffit vents to improve attic ventilation before you consider putting in a fan. This is because an attic fan does not take moisture out; it only takes the heat out.
LESLIE: Now we’re going to take a call from Jenette in New Jersey who’s looking for some advice on a good attic fan .
Jenette, how are you? How can we help?
JENETTE: Yes, I live in central New Jersey and I have a small ranch house. I don’t have central air conditioning  and I was considering looking into an attic fan and I need to know what type and any AC you can think of.
TOM: How old is your house, Jenette?
JENETTE: About 40 years old.
TOM: So it was built in the 60s?
LESLIE: And she’s looking for a fan that sort of sucks the warm air out and out through the roof and sort of helps the cooled air circulate.
TOM: Right, right. Now in theory, an attic fan would be mounted on the roof and it would draw air out of the attic. Now I’m going to say that it’s probably OK, in this particular house, to install an attic fan because you don’t have central air conditioning. Now if you did have central air conditioning, I would tell you not to install an attic fan and here’s why. Because typically, attic fans are so strong that not only do they take the hot air out of the attic but they reach down into your house and take the cool air out of the house as well.
JENETTE: Oh, an attic fan will do that.
TOM: Yes, an attic fan is definitely strong enough to do that because there are hundreds of holes in the structure of the house that allow it to do that. For example, every place that there’s an outlet there is a connection to the attic where I have seen attic fans turn on and those outlet areas basically become depressurized where the hot air jumps in there, goes up through, and right up to the attic. So an attic fan is definitely strong enough to do that.
I generally will recommend that you use passive venting before you put it in an attic fan. And by passive venting, I mean you put in ridge vents at the peak …
JENETTE: Yeah, we do have ridge vents at both ends of the peak.
TOM: No, that’s not a ridge vent.
TOM: If you say you have vents at both ends of the peaks, those are gable vents. Ridge vents go at the peak of the roof. They replace the ridge shingles that go all the way down the top and they’re more effective than gable vents. And in a 1960, 1965 house, you’re typically not going to have enough ventilation. And I’ll tell you something else that happens a lot to homes of that age, and especially in the northeast, is over the years you get a lot of condensation because you don’t have enough ventilation and the plywood rots out. So improving ventilation in a house like that by installing ridge and soffit vents  is a good idea.
And one more reason that that’s better than an attic fan is because an attic fan does not take moisture out; it only takes the heat out. The moisture forms in the winter time and the attic fan is just not going to come on then.
So for all those reasons, I would say that you’re better off putting in passive vents. And if you had air conditioning, I definitely would never put in an attic fan.
JENETTE: Well you’ve given me a lot of options.
TOM: Any more questions, give us a call. 1-888-MONEY-PIT.