apostolakisl
Senior Member
I am thinking my next step is going to be to put a return into the closet and possibly a duct fan to keep air circulating. Probably about a 4-6" line and T it into the main return for the upstairs AC unit.
You should consider putting a damper that allows you to switch from venting the heat into the HVAC return or venting it to the outside/attic. In the summer months you may not want the hot air getting pushed into the hvac system, especially while it is cylced off since it will cause a trickle of hot air to come out your vents elsewhere in the house.