Water heater and furnace vents sharing common chimney connection

Hi guys,

This came up on a mock inspection that I did earlier. The larger vent is coming from a gas furnace to the chimney, the smaller vent is from the water heater. The home owner assured me that this is correct per his plumber nephew. I’m not so sure and leaning the other way and told him so. I’m interested in your thoughts.


And it is run horizontal?

The connection is OK, instead of thinking up and down, think upstream and downstream, the WH connector should be downstream of the larger appliance the furnace, which it is. As for the rest, in your pic it looks as if the small pipe is pointing down, but that could be the camera angle. The other unknown is pipe sizing, for that you need the gas code, appliance size in BTU, and chimney diameter and height, but that is outside a home inspection scope, sizes look OK from here :slight_smile: