Power vent + direct vent?

I don’t think I have ever seen this before… a furnace exhaust vent, single wall which empties into a horizontal B-vent, that goes vertical, then out the roof. A direct vent water heater also connects into the B-vent. This doesn’t seem smart to me, as the air movement by the furnace could slow or back draft the water heater…
What are your thoughts?


I don’t have an answer for you . I’m a new inspector but I wondered what the turns ( elbows ) were like. Were they 90’s or 45’s or less ect… and how long was thThanks

how long was the run?

picture would be useful. Direct vent appliances should not be using b vent. Where was the combustion air coming from?
Go to manufacturers site and download the installation instructions for the water heater for correct installation procedure.

I don’t see how a horizontal B-vent can ever be correct.