I saw the previous cold air return thread. I have maybe a slightly different question and know little about HVAC systems. In my house (7 years old) in Minneapolis, I have a forced air furnace in the basement with a cold air vent (flexible 6-8" duct that falls to the floor, shaped like a U pointing upward, and located near the furnace). Last week I measured brisk air flow at 10oF coming from the outside and was wondering whether this is the reason our finished basement runs 5-7oF cooler than my 1st floor where the thermostat is located (usually set to 65F). We have warm air ducts that blow hot air into the basement but maybe no air return back to the furnace. What can I do to warm up my basement so that it is closer in temperature to my first floor temperature? Is there a simple fix to this problem? Does it make sense to heat the air coming in to the house from the outside? Better recirculate the air? Thanks.