Thread: Combustion Air Exhaust

A newly installed gas hot water heater I inspected recently had a small blower fan installed at the base of the vent stack that had a horizontal run of approximately 3 ft. before it exited the adjacent wall, which then had a vertical stack of approx. 5 ft. before it exited the roof. This is the first time I've seen this condition (Florida) but I was informed by a local HVAC company that this was an acceptable method of facilitating the exhaust of the combustion air. Has anyone seen this condition before and if so what state and what are the pros and cons.

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If it's what I think you're describing it's called a "fan in the can" and they work very well.

It is a far superior way to introduce combustion air into a room versus holes in the wall or pipes into an attic.

Got any pictures jp?