I own an old house. The furnace/blower was located in the hall w/ the return air directly underneath & supply located in the centers of MOST of the rooms. I replaced the unit and put the furnace/blower in the attic. 3 new, 12" round returns were added, 1 in the den, 1 in the living room & 1 in the master bedroom. The house is 2500sf, ranch style, 5 ton unit.
I need to replace the sheet rock on the ceiling in the master bedroom, & I thought it would be a good time to move the suppy to a more efficient location. The master is 13.5'x17.25'. The return is located near the center, along one edge of the 17.25' wall. There is a 35"x70" window on each of the 13.5' walls (near the centers) and the head of our bed will be near the center of the other 17.25' wall(opposite the return). The supply is from a trunk line that continues to a hall and large walkin closet. I want to run a new line to just the bedroom, but what size duct and where should the suppy/supplys be located? The master is approx. 18' from the main supply plenum.
Also, there is NO supply in the dining room! The dining is 13'x12' and located almost directly below the main supply plenum. The thermostat is on one 12' wall. What size supply duct in this room and the location?