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 Water heater outlet backflowing
Author: Bralich (TX)

I have a dilemma. My water heater was "spraying" water out of the top air vent/draft. There wasn't any water leaking from pipes, seams, etc. All the water was coming out of the top of the heater where the vent is. I called the manufacturer and they said I need to take out the heater and replace it. Ok, no problem. I shut off the water and detach everything and turn off the water inlet valve on the cold water pipe. I turn the water back on and water starts to "backflow" out of the hot water outlet where it is attached to the top of the heater. I figure air or left over water is in the pipes, so I turn on a hot water faucet and sure enough the water stops coming out of the hot water pipe. I leave the faucet on for...an hour! And water is still coming out of the faucet, not a lot but a small stream of water. I know there isn't that much water in the pipes and turn the faucet off. Boom. Water starts coming out of the hot water pipe where it is supposed to attach to the heater. Again, not a lot, but enough. Turn the faucet back on and again it stops.
I call a "free" plumber who says that is normal and as soon as I put the water heater back on it won't do that. That would be a simple explanation, but....
I'm thinking the water backflowing was the problem. I've never heard water backflowing into the heater tank before and what would stop it?
Any ideas?

Edited 1 times.

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 Re: Water heater outlet backflowing
Author: hj (AZ)

Somewhere in the house, usually at a single handle faucet, the core/cartridge has failed and is letting cold water flow across to the hot side. Anyone who says they have "never seen this happen" has NOT been doing plumbing for very long. First replace the heater so you can turn the water back on, then search for the problem/solution or call a "good" plumber to find it.

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