We have a new 2-story house under construction right now, and it appears that the HVAC contractor is putting one large return for the upstairs HVAC system (separate system), which covers 1300 square feet, in the upstairs hallway. The floors will be all hardwood, and there will be gaps under the bedroom doors (4 bedrooms upstairs) with the doors closed.
Is it better to have a separate return in each room, or will one large one in the hallway suffice, provided there is enough airflow under the doors, or if the doors are left open. If returns are placed in the individual rooms, is there a best location for them? The ducts are all run through the ceiling. If returns are in the ceiling as well, should they be spaced a minimum distance from the ducts?