Thread: water heater exhaust damper

Today I saw a high efficiency water heater that exhausts through pvc terminate at a back-draft damper outside. This can't be right, can it?

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JA: It is my understanding that ultra-efficient heaters use sealed-combustion technology so they cannot backdraft. The damper would then be moot, if not specifically disallowed.

It's a Rheem power vent and I looked up the installations specs. While they don't say "no back draft damper", they don't show one as an option, either. Just the pipe with a supplied screen.

JA: I cannot think of a reason why it would be prohibited, but I have also never seen this installation before.

John, is it possible that the damper could freeze closed due to the moisture in the products of combustion? I've never seen one on high efficiency equipment.

Originally Posted by neal lewis

John, is it possible that the damper could freeze closed due to the moisture in the products of combustion? I've never seen one on high efficiency equipment.

I think that's possible, based on warnings about freezing in the installation specs.