Some homes have return air vents in every room other than the bathrooms and kitchen. Others only have one large return in a common, central spot like a hallway. Something to consider when thinking about whether to close doors.
I have a return in the basement as well as a supply vent. The return is always wide open. The supply vent gets closed in the summer, otherwise the basement is too cold. If I leave the basement door open, it also gets too cold in the basement.
What is good for one house may not be good for another. (We have returns in each room).
