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Scorched water heater


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First time I've ever come across this. A.O Smith water heater manufactured in 2003, same year as the house was built. The vent pipe is not shared with anything else. The draft hood is well attached. Nothing else seemed wonky.

I'm looking for your thoughts...

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IDK - The home is vacant. This is what I put in the report, but I have not sent it out yet, so it may change.

FYI: The water line connections to the water heater are scorched. This was caused by hot exhaust gasses spilling out from under the draft hood. I found no problems with the vent pipe. I can only assume that the condition that existed for the scorching to occur, no longer exist. Ask the seller if they know anything about this.

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I agree, skip the assumption about no longer backdrafting. It looks like there was a huge amount of exhaust gas spillage, possibly because of a negative pressure situation in the garage, or perhaps a dead squirrel blocking the vent pipe. It could still happen sometimes, and needs to be ruled out by not you.

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A pro certified in CO/combustion analysis should test and correct as needed. The vent connector should rise straight up as far as possible while still making room for the 1/4" per LF slope up to the vent. The vent connector should be supported at the offset and every four feet. The vent should be inspected for obstruction (level II). There could be a a flow obstruction such as damaged inner liner or the use of TEK screws pushing in the inner liner instead of piercing it and pulling the two single walls together. If the B-vent joints have any screws, this is a common defect. A worst case depressurization test should be conducted.

There is either a flow obstruction or a depressurization issue WRT the CAZ. This is just another reason to remove draft hoods--they work just as designed. They are the most dangerous item in a home. An NCI pro knows how to make the repair to a bullhead tee with double acting barometric damper and spill switch. Backdraft must always be investigated and corrected or somebody could wake up dead.

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...or somebody could wake up dead.

Is that how them zombie's are created?

I wonder if the backdraft is confined to the winter season when the entire length of the flue is subjected to cold winter temperatures? These are Illinois winters and not an inch of the flue runs through conditioned space.

Marc

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This can't be complicated. Flues draft and work when installed correctly and they're not blocked. That much corrosion means something was/is wrong for a while.

Agreed on the punt. It shouldn't be hard for someone to figure it out.

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