I recently added a room to my house by way of turning the garage int a nice bedroom. the attic and walls are insulated and garage door now a appropriately installed wall .
My a/c vents were installed a year ago by a local a/c contractor but the ducts ran into the rear of the garage which was wallled off to the main garage area. they have been moved foward now into the bedroom. he was aware i was going to do this and the tonage is correct . the problem i'm having is figuring out the right size duct for a ceiling return are duct and if it's ok to ad the to the air handler system . he had a 6 by 10 vent in the wood box but hadn't cut the insulating box behind the vent.
I would like to do the return air thing since the rest of the house is done that way and this is not an open air handler like the old days