We live in a big 3 level house with the woodstove on the main (middle) level. The bedrooms and furnace is on the bottom level in the basement and my sewing studio is on the top floor. The basement is usually 15 to 25 degrees cooler than the main floor. We have 2 air returns to the furnace, which is always set on "house fan". One is on the main level where the wood stove is and one is in the basement ceiling (don't ask me why). So the warm air from the wood stove gets sucked in the main floor vent and heads to the basement where the vent there adds cold basement air to the mix to be blown back through the house. The vent is in closed position, but it was not helping. Tonight it is really cold out and the basement is cold too, despite the woodstove. It (finally) occurred to me to slap a couple magnetic bumperstickers on the vent to force the air to all come from the main floor vent! YAY for BYC!