cold water feeding into hot water supply

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by traff_ss, May 13, 2007.

  1. traff_ss

    traff_ss New Member

    May 13, 2007
    Yesterday, I replaced a gas water heater. Everything went okay, except I noticed something weird. After shutting off the gas and the cold water supply into the tank, I hooked up a drain hose and started draining the tank. I then unattached the hot water line (output) to help the tank drain quicker, and put a bucket under the line since I have a two-story house and I figured there would be water in the line.

    To my surprise, there was A LOT of water, under pressure, coming out of the hot water line. In fact, I had to run out and shut off the main before I filled the bucket. Obviously, cold water is feeding into the hot water circuit at some point. I have an old house, but all of my fixtures are pretty new (most in the past two years).

    I tried an experiment: I went around the house and shut off all fixture and cold, for all sinks, toilets, washer, etc. The only one I could not shut off was the upstairs shower (there is no cut-off). I turned the main back on, and I still had a steady stream of cold water coming out of the hot water line.

    Anyone ever see this? Any ideas on how to fix?

  2. Dunbar Plumbing

    Dunbar Plumbing Master Plumber

    Apr 18, 2005
    Service Plumber, Outdoor Temperature Relief Owner
    Northern Kentucky/Greater Cincinnati Area
    If you did not have any problems with this reversal of flow before.....more than likely the hot/cold lines are reversed into the tank and someone moved the dip tube to the hot outlet side. Common in the older homes when a loop was installed backwards to test off the water lines.

    Might just have to jot the pipes around to make the new one, right.
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