Product review (1 stars): poor Idea
these are bad for your house.  they allow moisture in to your house which causes mold.  it you have build-up of moisture on the windows then you have a problem.  If you hook this to a gas drier then you also get carbon dioxide in your house.  if you really want moisture in your house then don't use the fan when you take a shower. you shouldn't need more humidty in the house if you cook, bath and breath.