Whole house fan - 2 story house


Old 05-25-08, 12:05 PM
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Whole house fan - 2 story house

Will a whole house fan work well in a two story house? My house is 3,000 square ft. 1,500 up and 1,500 down. Should I get a big 36" attic fan that will move a ton of air and hypothetically cirulate the whole house or should I just plan on it working for the upstairs only and get a smaller (24 or 30") fan.


Last edited by garykral; 05-25-08 at 12:15 PM. Reason: Want email notification
Old 05-26-08, 07:00 PM
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I would get a smaller unit, and when you are downstairs, open the windows down there where you want air movement, and when at night close down some of the lower windows and open the upstairs.

I would think a larger fan would make more noise than you'd like to have at night when you are trying to sleep. I've never been around one so I couldn't say.
Old 06-02-08, 09:47 AM
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We're in a similar situation and I just installed mine this past weekend. I have a 2,500 sqft two-story house in so cal.

I went with the 30" GAF from Home Depot... < $300.

Normally, I have an eight degree swing from downstairs to upstairs by the end of the day. I only have one day under my belt since I used it for the first time last night but for the first time in my history, I cooled the upstairs down one degree lower than the downstairs!

I ran it for an hour and had three upstairs rooms windows opened about 4 inches each.

The only negative thing were noisy louveres. They rattled while the fan was on. In my case, it seemed that the rattling is better when fan is on High. I have adequate ventilation but I think all the insulation in the attic is probably deflecting a lot of air flow. If it were empty of insulation, I bet the noise would be less.

Things to note if/when you install it. The Plenum boards really make a big difference. There was one 17" section I forgot to enclose with a Plenum board and when I turned it on to test it, didn't see much movement from the drapes around the open window. I went back up, cut the Plenum to fit and installed it. When testing it again, the drapes went wild and you could really feel that nice breeze come into the room.

Best of luck! Feel free to ask questions while this is still fresh in my mind.
Old 06-02-08, 02:45 PM
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If your in an area with high RH the fan may not be a good idea
Old 06-20-08, 12:16 PM
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We have one as well and our house is 2 stories plus a basement. 4000 sq ft all together. 1 WHF does wonders. We have to have ours on a timer because if we leave it on all night we'll wake up cold.

You'll want to make sure it pulls air for the whole house. That way it can pull cooler air from downstairs upstairs and the even cooler air from outside.
Old 06-23-08, 10:48 AM
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A bunch of tips--
Size the fan for the whole house. Open windows in the areas you wish to ventilate. Use the speed control as needed. Belt drive fans tend to be quieter, as they run slower. Smaller fans run faster & make more noise. Locate the fan in the upstairs hallway ceiling. Mount the fan on some sort of sound isolating material, like foam rubber or felt.
In my house, I installed a large vintage two-speed belt driven furnace blower in the gable end of my attic. It draws through a louver in my upstairs hallway, and is controlled by a timer. It is extremely quiet and cools the house down quickly in the evening.
As mentioned, it's great for days when the humidity isn't an issue. Just don't use it when the humidity is up.

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