Attic Fan Woes: UPDATE

[timbirr]

For those of you who may remember, I posted during the past weekend (Jn 10) about roofers plopping a new attic fan into my roof and leaving the wiring to me.

I hooked it up and nothing happened, even tho. the temp should have been hot enough to have it kick on (I had set the thermostat to 60 degrees and it was 74.5 in the attic according to my little thermometer).

So, I asked if anyone knew why. Got lots of opinions, even had a detour into how to use a Volt-Ohm meter....then someone asked if there was a light switch of some kind that I had no idea what it controlled. Happened that there is a "normal" looking wall light switch pretty much on the wall in the house hallway. And if you drilled a hole through the ceiling just above the switch location into the attic, you'd be pretty close to the fan location.

Anyway, looked and that switch was off. So, I flipped it on, but since it has been in the 50s-60s all week temperature-wise and I had reset the fan thermo to 102, nothing has happened. Well, it hit 90 today and the fan is whirring away....it is a little noisy though. My wife says it sounds like a helicopter. Well, that is a MAJOR lie, but it is a bit noisy....but anyway it does work!!

For those who care, it's a GAF Master Flow "roof-mounted power vent." I can't find any specifics in the manual about flow or anything, but it is a monster compared to the unit it replaced. It about three times larger....

[Proctologically Violated©®]

You can replace the motor/fan blades if necessary. Hard to say if there will be an improvement, noise-wise.

My attic fan really sucked, motor froze up. Kluged an oscillating fan in there, worked good for a while (very quiet), but froze also.

Finally put a fan from a window A/C unit in there, worked great until the capacitor blew. Powerful, not as quiet as the first replacement, but no noisier than the original.

NOW, new (well new-used) capacitor, works fine....

.

[trader4]

Since you think the new fan is a lot bigger, make sure you have adequate intake vents, eg sofftit venting that is not blocked. Otherwise, you can wind up sucking cool air from inside the house through leaks, negating the fan benefit in helping lower AC needed.

[Proctologically Violated©®]

Since you think the new fan is a lot bigger, make sure you have adequate intake vents, eg sofftit venting that is not blocked. Otherwise, you can wind up sucking cool air from inside the house through leaks, negating the fan benefit in helping lower AC needed.

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But doesn't that help bring up cold air from the upper levels, helping cool the upper levels to some degree? And vent some of the hot air accruing on the top floor? Sort of the purpose of a "whole-house" fan?

[trader4]

He has an attic fan, not a whole house fan. An attic fan is used in an attic which is supposed to be sealed and insulated from the living space which typically has AC. I say supposed to be sealed, because there is still going to be leakage. For example, take a look under a bathroom sink and you'll find holes into the wall for plumbing. Put an oversize fan in the attic without adequate intake vents and it will suck conditioned air through those random openings, resulting in energy loss.

A whole house fan goes in the ceiling of the upstairs and is used without AC system, or at those times you can use it instead of AC. It draws a large volume of air through open windows in the house and pushes it into the attic and then out through attic vents.

[mm]

That was I, more or less. Glad you got it fixed.

A whole house fan has to be used when the outside has cooled off, to suck somewhat cool air in from the outside.

A roof fan runs during the hot and hottest part of the day, and turns off between 5 and 9 pm.

So I don't know how much the bigger fan would suck out, but it would be the wrong temp.

This winter I put foam around my trap door because I worried about passive air currents from the second floor.

There is also the stack, which runs from the basement to the attic. I don't know if the heating duct is supposed to have sealing between it and the second floor, but I wasn't able to seal the half inch hole I drilled for various wires. Not sure how much air would leak out through the bathroom vents. Otherwise it seems pretty well sepearated.

[timbirr]

Well, thanks for that suggestion, because I was going to think about incantations under the full moon pretty soon. LOL.

I'm in Oregon, the hottest it gets here in a normal summer is about 95- ish, and then not for many days...usually in the 80s. No AC in this house, but the GAF manual does have a whole section about soffits and how big of fans to install and not to install more than one unless you have XXX numbers of soffits, etc. , not that I read it....

[trader4]

Might be a good idea to read it, unless you want a big fan using more power and sucking air from the house, because it doesn't have adequate intake venting.