In article , Huge wrote:
So common, in fact, that in some 27 years of regular visits to the US, I've
never seen one.

Google gives 16,400 hits on "attic fan"

As this is a d-i-y group:

http://www.easy2diy.com/cm/easy/diy_...ge_id=35693815

gives you instructions

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Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
Free SEDBUK boiler database browser http://www.sda.co.uk/qsedbuk.htm