I've been so happy with the 2 stage/variable speed trane furnace for the main living area, i'm considering replacing the 17 y.o. single stage furnace xe90 upstairs (when I replace the failing air conditioner up there).
The furnace is shoved in a closet, and sucks air from a ceiling louvered grill that connects directly to the attic. Dust particle collect along the cracks of the closet door, so i'm pretty sure a good bit of conditioned air is used for combustion.
How important would adding a roof connecting PVC pipe to this set-up for intake air? Can I ask the pros and cons (my big con would be drilling the hole in the roof and getting it properly sealed)?