Hot And Cold Reversed Throughout House (Temporarily)

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    • #276674
      Avatar photoCecile Isaacs

        Trust me, I’m not making this up. As far as I know, what happened in my house the other day is physically impossible yet it really happened.

        The other day my son noticed that the water coming from our single handle kitchen faucet had the hot and cold reversed. When he told me this, my wife added that the water in upstairs shower (a three handle faucet with center diverter) was also reversed. I checked every other fixture, and found that all fixtures were reversed, including the toilets! They were flushing with hot water. I’m not talking about luke warm out of either side, I’m talking about full cold from the hot side and steaming hot from the cold. I even had my neighbor come over and check it out to prove to myself that I wasn’t nuts. We considered the dip tube in the water heater, but that wouldn’t explain the complete reversal of hot and cold. Before we could figure it out, the problem went away and has not returned.

        Can anyone explain this occurrence?

      • #294574
        Avatar photoracefanone

          If it happens again ,shut off the water supplies to the single handle faucet and see what happens.Sounds like a cross connection.Also if you have any other single handle valves do the same.Kind of a shot in the dark to figure out without being there .

        • #294575
          Avatar photodadofchamp

            I did close the shut-offs to the kitchen sink but not any other single handled faucets. It didn’t change anything, although the pipes could still have been filled with the “wrong water”.

            One of the strangest parts was that the basement toilet, which is T’d off the incoming line, about 1 foot from the pressure reducer, was flushing hot. I can’t possibly figure out how hot water could have made it into that branch of the plumbing. Water has to come IN through the pressure reducer, so how could hot water have made it back that far into the system?

            Is it possible that some sort of loss of pressure from the street forced all the cold water pipes to be filled with hot water and until they were drained the cold side ran hot? But how would that explain the hot side being cold?

          • #294576
            Avatar photonicktheplumber

              Dear doc,

              I can’t explain your problem, especially your statement that the toilet that tees off the cold water supply (presumably before it goes to the inlet of the water heater) is filled with hot water. I was thinking that maybe your water heater had reversed inlet/outlet connections, or that your supply lines were plumbed backwards, but the basement toilet can’t be explained by either screw-up. Still, you might try reversing the connections to the water heater…


            • #294577
              Avatar photoRetired plbg1

                It could have bypassed in the tub valve are wash machine are any faucets you have connected wth hoses.

              • #294578
                Avatar photodadofchamp


                  This is not a new install, so reversed plumbing at the water heater or anywhere else isn’t the problem. This was one time occurance which only lasted a few hours. Besides, reversed pipes at the WH wouldn’t cause these symptoms. I would just run out of hot water VERY quickly as the cold water filled the tank from the top and colder water was taken from the bottom. I would still get cold from the cold water faucets. (Been there…WH was plumbed backwardswhen I moved in 20 years ago. The previous family of 4 lived that way for at least 5 years according to the install docs that came with the WH!)

                • #294579
                  Avatar photodadofchamp

                    Retired plbg:

                    The washing machine is indeed attached with hoses. If it happens again, I’ll check there. Thanks!

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