i live in a double wide mobile home and the duct work stinks. some vents blow out good and others have hardly any air coming out at all. now my question is should i replace the duct work or buy a new unit with a varible speed motor and run the fan all the time. my instructor told me the the varible speed running all the time would not use much power and would even out the house. i have read on this site for some time now and have gotten some good ideas, so i thought i would see what u guys think.