I am installing a suspended ceiling in a room where the heating/cooling register (approx. 8" x 11" overall) is currently at joist level. The new ceiling is 4" below the joists. How do I go about extending the duct to mount the register on the underside of the ceiling panel? Or do I simply angle the horizontal section down so the end finishes up at the right level?
BTW, this the room I mentioned in a previous message that has a heating/cooling register but no return. (Our bathrooms are the same, I now realize.)