Gable Fan?

Ok, I just had a new roof with a ridge vent installed on my Cape, along with new siding and perforated soffit vents. There are also gable vents on either end.
Because of the configuration of the upstairs hallway, installing a whole house fan will be difficult (and I don't want to put it in one of the bedrooms). Also, I understand that whole house fans do a good job of pulling in HUMID cool air, as well as being noisey.
I'm interested in a gable fan - cooling the attic space, and leaving my dry air conditioned air alone on the second floor.
Is there any danger of the fan pulling in rain water through the ridge vent? Are they typically a low amp type of deal - meaning could it be wired into an existing outlet near by, or does it need it's own dedicated circuit?
Also, somebody said I shouldn't even have gable vents anymore, as there is supposed to be a flow between the soffit and ridge vents - and the gable vent will eliminate that. Should I just have one gable vent with a fan and cap the other one?
Thanks
-CF
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Ok, I just had a new roof with a ridge vent installed on my Cape, along with new siding and perforated soffit vents. There are also gable vents on either end.
Because of the configuration of the upstairs hallway, installing a whole house fan will be difficult (and I don't want to put it in one of the bedrooms). Also, I understand that whole house fans do a good job of pulling in HUMID cool air, as well as being noisey.
I'm interested in a gable fan - cooling the attic space, and leaving my dry air conditioned air alone on the second floor.
Is there any danger of the fan pulling in rain water through the ridge vent? Are they typically a low amp type of deal - meaning could it be wired into an existing outlet near by, or does it need it's own dedicated circuit?
Also, somebody said I shouldn't even have gable vents anymore, as there is supposed to be a flow between the soffit and ridge vents - and the gable vent will eliminate that. Should I just have one gable vent with a fan and cap the other one?
It sounds like you should leave well enough alone. A ridge vent with good soffit venting should be all you need. Some people are of the opinion that the gable vents will short circuit some of the air by allowing air to come in the gables and exit via the ridge, instead of coming up through the soffits. In practice, I doubt this is a problem worth worrying about. One thing for sure, adding a power vent into this equation is unlikely to make things better and may make them worse. Why do you think you need a powered gable vent?
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Not a powered gable vent. I'm talking about a gable fan.
The reason I want one is because it becomes unbearably hot up there in the summer.
-CF
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CFster wrote:

    I have a similar situation except I do not have ridge vents in my roof. My furnaces are in the attic and of course the evaporator coils are in those furnaces. Since here in the south it is like placing cooling coils in a oven in the middle of summer when the attic gets hot, I placed a thermometer in the attic one day to see just how hot it got. It was well over 115 degrees with only natural convection through eave vents and the two gable vents I have.
    First I looked for a circuit that powered only bedroom outlets or lights, and tapped into it for power to a couple of gable fans I installed. Since I was doing the wiring, I also installed a switch accessible in a closet so that I could disable the fans anytime I did not want the fans to run. Times like going on vacation etc. meant that I was not running them when they were not needed as I also turned off the A/C then as well. The motors on most exhaust fans use something like 1/5 HP and do not consume much current, so when added to the existing circuit I tapped into, there was no danger of exceeding its rating. The fans have a thermostat that can be set to turn on at 90 degrees or more and they turn off when they fall below the set level. When I measured the temperature again after installing the fans, the temperature never exceeded 100 degrees. Keep in mind it is normal for us to have most days in July and August in the high nineties. Since the sun beating down on the roof is primarily responsible for the attic temperature and not the outside air temperature, changing the air in the attic is what cools it.
    With regard to natural convection via ridge vents: I am sure they do some good and since they are designed to prevent rain from being blown in during a storm, I would think it is unlikely that a power gable vent would pull in water if it was raining. It is important that you have eave vents and that they are not covered with insulation or other material. It might even be wise to add more such vents if you can. I however believe a power vent or vents move much more air and consequently lower the temperature in the attic much more. If your furnace/air handler is in the attic, I would suggest you follow that route. It along with added insulation in the attic have made a major impact on my cooling costs.
Ken
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"Not a powered gable vent. I'm talking about a gable fan. The reason I want one is because it becomes unbearably hot up there in the summer. "
Well, now I'm confused. You said you were considering putting a fan in the gable in the attic and leaving the conditinoned second floor space alone. What is that, if not a powered gable vent? And where does it become unbearably hot? In the attic? That is normal with any attic, even if it's properly vented. You want to reduce the temp from a possible 140 to a more reasonable 110 or so, not get it to room temp.
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Yes, an exhaust fan that goes behind the gable vent. Sorry if I got the terminology incorrect.
-CF
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On 28 Jan 2006 16:31:28 -0800, snipped-for-privacy@optonline.net wrote:

Of course they pull in humd air, if tahat is what is outside. And don't assume the outside air will be cool. It will only be cool when it is cool outside. and that might not be until 8 or 9 PM, or later-- I forget. So when you want to sleep,or at least when you are home, that will be the very time you have to run t e fan.
A gable or a roof fan runs mostly when you're not home, in my case from about 10 in the morning until 7 in the evening, and because it is so much farther from me, I can barely hear it. usually I need to turn it off at the switch I have in the upstairs hall to know if it is running or not. (Or course I leave my windwos open all summer, so there is never dead silence in my house in the summer.
If you store things in the attic, it's better too, because you're not heating them to 140 and then cooling them off every day. I think the thermostatt came set at 85, but it does get up to 100 or maybe 110 in the attic, but no hotter than that.

I have a roof fan. Rain lands on the roof just outside the fan and bounces into the screen. some of that bounces back, I'm sure, and some goes through the screen and lands on the floor of te attic. It's a piece of plywood. I've never found it wet, only a little moist. Never soaked in even a millimeter, afaik. 22 years, and no damage, but nothing there to be damaged. I would not leave clothes or finished furniture underneath the fan.

Don't remember. I have one light in the basement and one light in the attic on the same 15 amp circuit. It' snever blown a fuse. I have gone through 4 motors in 22 years, some last a long time and some as little as 2 or 3 years. Don't know why. Change them from the insdie of course and I think I've gotten the time down to 30 or 20 minutes. Theres a motor repair store in Baltimore that sells exactt replacments.

I guess it matters how high up your gable vent is. I have a friend with a very low one, becauwse it is meant to replace the soffitt vents she doesn't have. If your gable vent is high, there is much less air about it, and some air must vent through the ridge vent without fan assistance.

Maybe it should be, but that certainly wasn't my experience. I had a full length ridge vent (in a townhouse about twenty ?four? feet wide) and full length without interruption soffit vents in both the front and back of the house, about 4 inches wide. The center of the attic is about 7 feet high, and (if it matters) the shingles were dark brown.
BEcause I don't use AC, I would come home about 5 or 6 pm and it would be so hot upstairs in the summer, I stopped gooing up there. I would sleep on the loft bed in the basement, and go up the next morning to shower and get new clothes.
After the fan went in the attic, it was at least 10 degrees cooler in the 2nd floor, and maybe 40 degrees cooler in the attic.
BTW,, after about 15 seasons wtih the fan, I noticed something that looked like the line from a dryer lint filter on much of the soffitt. I couldn't really see it from the ground but I could from a latter, and I peeled it all off. I'm sure without the fan, there wouldn't have been so much venting or that layer.

Remove NOPSAM to email me. Please let me know if you have posted also.
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