Just inspected a condo with a room off of the hallway that houses a high efficiency furnace and hot water heater. The doors to the room I am calling a Mechanical room are solid, no louvres. There are 2 registers/grills in the room on the wall one at floor level and one close to ceiling. I am assuming this is for combustion air but I can’t verify as they are behind the unit and I don’t have access. I am concerned about adequate air make up with solid doors. BTW, the unit discharge vent pipe looks like it goes straight up to the roof. The air intake is a short piece of PVC off of the unit (not to outside).
Any comments are appreciated.