Quote:
Originally Posted by S-F
If you live in the house in the winter you may want to start thinking of ways to air seal that thing. It is in no way easy. When I run the blower door on a house with a regular whole house fan and then remove it from the equation by sealing it up (I guess a lot of people don't value them???) the air leakage reduction is absolutely stupefying. I'm talking about some really serious numbers with the blower door. On the order of hundreds of CFM @ 50. Sealing one off completely appears to be much like sealing off a plumbing bypass roughly the size of a standard double hung window. When they are removed after the test in for my job there but before the test out the results are even more staggering. It's like closing a door to the outside. I have yet to be able to reproduce such results with air sealing a decommissioned WHF but I always do give it my best. People are tearing these things out left and right here because when the auditor shows up with the IR camera and shows them the register for the fan they cry.
You will need to build a box made of some rigid substance which can be mechanically fastened to the.... whatever it gets fastened to and has a dead nuts tight air seal. That's something I can't do.
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I built walls around the whole house fan in the attic using 2 inch polyiso foamed together with GreatStuff foam in a can. Then a 2 inch thick polyiso lid on the walls in the winter and off in the summer. I throw FG insulation batts over all that.
I use weights on the polyiso lid to insure that it sits tightly on the polyiso walls.
It takes all of 3 minutes to do the changeover from summer to winter or winter to summer.
Very easy to build, and it appears to be quite effective.
I can't imagine being without a whole house fan in the summer -- it saves us from needing whole house AC at many times the energy cost.
Gary