I recently moved to a new house. The HVAC unit was working during warm days but did not fire during cold days.
Two contractors saw the unit and they agree that the exhaust pipe is too small for the unit and distance to the outside.
The unit is 100,000 BTU and the pipe travels around 29 feet with a few angles. The installed pipe is 2" in diameter
and according to the manufacturer's specification it should be 3". Picture attached
The first suggestion to fix the problem was to install a new pipe. This is not easy becaust I will have to open up the ceiling
in two rooms and the unit is on the fourth floor making it very difficult to access the outside vent, which is on the side of the house.
The other suggestion was to connect the exhaust and intake pipes with a Y and draw combustion air from the room. The Y would
enlarge the capacity of the exhaust pipe. The problem is that the HVAC is in a closet in the laundry room which is relatively
small. One contractor suggested drawing combustion air from the elevator shaft that is behind the closet, very close to the
My question is, is it ok to draw combustion air from the elevator shaft? Would the Y system work? Any other alternatives
about drawing combustion air without going outside? Should I just look into enlarging the exhaust pipe?