I have a raised ranch, which has a finished half basement. It is always cooler in the basement than the main level. There is one return on each level. The vents are in the floor upstairs and in the ceiling downstairs. And the basement is open to the main level via the stairwell.

I have always closed the basement vents in the cooling season and opened them in the heating season, figuring that cooled air will always find its way to the basement and warm air will move upstairs. So I'm assuming that this would be more efficient. But I recently read that closed vents in an unused room result in increased pressure forcing the ECM blower to work harder.

So should I keep the basement vents open at all times?