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stevedar 06-15-2008 10:38 AM

Whole House Fan Ideas?
I am deeply confused by the whole house fan thing. I live in the Seattle area and right now it looks like if it ever hits 72 degrees again we'll be lucky.

Anyway, I have a heat pump which provides nice whole house air conditioning on those rare days that the temp exceeds 80 degrees, so I don't want to invest a huge amount of money in something that is going to not provide too much value. In fact, in the winter it will be a pain in the neck because it will let my warm air go up into the attic.

The more expensive ones offer a "closure system" so that when it's not running it will stop the air from leaving the house. I guess letting the moisture from the house in the winter into the attic is also problematic.

Here's my idea. Since the attic it vents to is adjacent to the garage, would it be possible to vent it over to the garage instead. That is what if you bought some HVAC flex duct and took it up, then right back down. Would this not help relieve the moisture problem and provide LOTS more air space than trying to pack it into my 4x12 pitched attic? I also see an added benefit in that it could be used to heat the garage as well if I were working out there in the winter.

Would that work? Then could I get away with buying one down at the home improvement store for $265 instead of paying $550 or more?

pweller 06-19-2008 05:58 PM

I hope this isn't too obvious, but a whole house fan only works when it is cooler outside than it is inside. I find you need about a 5 degree difference for it to be somewhat effective, with a 10 degree difference it will be very effective.

Here's what I do. I have an Oregon Scientific weather station thing, which has a wireless remote sensor to put outside. These are about $40 at Target, and the better ones will show both temp and humidity inside and out. Now, if you find it is 80 degrees in the house and 72 or less outside, then a whole house fan will work for you.

If you want a cheap entry into the whole house fan, you can do something similar to what I did, which is to get two cheap box fans. My house is about 1600 sq feet, and you need two fans to really make anything happen. One does not move enough air. These are about $15 each or so. If your windows are big, you can screw the two fans together and put them in one window, obviously blowing out. These can be noisy, depending on the speed. Try to put them in windows so that they are working with the usual wind direction. If you find this system works, you might just stick with it - or you might decide it is worth the $500 for a permanently installed system.

I use the cheap method, because I know it works.

steve771 06-20-2008 01:59 AM

I used to have a whole house fan when I lived in Ohio. Worked pretty well, however, those babies move a LOT of air, so I don't know if ducting would hold up. It would have to be a very large diameter, IMHO.

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