Topic: Attic Fan
started by: TheCatt
Posted by TheCatt on Jul. 05 2011,13:19
Anyone here have an attic fan? (Fan that blows hot air out of attic, not a whole house fan).Our AC has issues keeping up with >90 degree days, and seems that a fair amount of cooling is lost in the attic where our second system has all of its duct-work. AC company wants to completely redo the duct-work (and/or upgrade the AC, which is 12 years old anyway; and inefficient by today's standards <10 SEER>).
Seems to me that blowing hot air out of the attic through the gable(s), letting "cooler" air flow in from the soffit ducts would do a lot to reduce the temps, possible more cheaply.
Posted by GORDON on Jul. 05 2011,14:00
I have one. It's on a temp/humidity sensor... if the temp hits 90F or humidity is 90%, the fan kicks on.Unk's is hooked to a wall switch.... in the evenings he manually turns the things on to draw cool air into the upper part of his house, the idea being that it keeps the house cool the next day during the heat. I do the same thing, if probably less effectively, with a window fan in my upstairs hallway.
Either way, I can't see how one wouldn't help considering my house attic in NC would hit 120F+ during the hot summer days.
Posted by TheCatt on Jul. 05 2011,14:14
I think the idea is to take advantage of the temp differential between the highest part of the attic (143 today in my attic, on a 92 degree day), versus the outside air/soffit temp (92-100), so that the attic isn't just a heatbox radiating heat to the ducts (and to a lesser extent, the house itself). It doesn't draw up cool air from the house, but rather the relatively cooler air from outside.
Posted by TheCatt on Jul. 05 2011,14:15
Posted by GORDON on Jul. 05 2011,14:22
Yeah, exactly. But an added bonus is going to be that the cooler the attic is, the quicker heat will rise from the lower levels, unless you have uncommonly thick insulation for the NC area and you have zero heat transfer in your upstairs ceilings.Which means the AC will kick on less, as it doesn't need to work as hard to heat your living space.
Posted by TheCatt on Jul. 05 2011,15:56
(GORDON @ Jul. 05 2011,17:22)
QUOTE
Yeah, exactly. But an added bonus is going to be that the cooler the attic is, the quicker heat will rise from the lower levels, unless you have uncommonly thick insulation for the NC area and you have zero heat transfer in your upstairs ceilings.
Which means the AC will kick on less, as it doesn't need to work as hard to heat your living space.
Which means the AC will kick on less, as it doesn't need to work as hard to heat your living space.
Wait, you completely lost me there.