I have a central natural gas forced-air furnace in a small (1500 sq. ft.) home. I have an unfinished main room downstairs and a room for storage upstairs that's not being used as a bedroom.
Is it cost effective to close the heating vents in these rooms? I'm fairly confident about the unfinished basement room, but not so much the upstairs room. The reason being that there's a return air vent in the storage room: the door stays closed and the return air vent isn't getting anything to return.
Upstairs there are a total of six rooms: kitchen, living room, bathroom, and three bedrooms. Each of these rooms has a vent. Each bedroom and the hallway connecting them have return-air vents. The thermostat is located in the hallway.