[cabmandone]

Just for the purpose of clearing the air (pun intended), An electrostatic filter uses no electricity. I'd strongly suggest a good filtration system and running your fan continuously. Running the fan has two benefits. 1: Better filtration of the air, 2: More even temperatures throughout the home. If you have metal duct have it cleaned and make sure they do each run off of the main trunk not just the main trunk itself. If you have the lazy installer duct (flex duct) you're probably best to get rid of it as it has a lot of static electricity and tends to catch a lot of dust. For best filtration your home should have one "return" duct in each room.

BTW, MRM great catch! After reading again it does appear he could stand to check humidity.