We just bought a relatively small home, 1400 sq ft here in Boston. The first floor is 1/2 below ground level and is always quite cool, and the second floor is always warm, even when it's in the 50s outside. The HVAC system was installed new less than a year ago and heats the first floor quite well. To keep the second floor from getting even hotter i've closed all the vents on the second floor. My question is regarding return air. The system only has one air return vent, that being on the second floor. Does it matter that there is no return on the first floor, and would putting one in make a difference to stabilize the temperature between the floors? I could fairly easily install a return air vent on the ceiling of the first floor and am wondering if there would be any benefit to doing so? Ideas?
Thanks in advance!