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  • Boiler expansion tank

    Why should there be water coming out of the tank when I depress the schreader valve on top? Also I have a house that is only used for an occasional weekend in the winter, I shut the water main off when I leave and when I return in a week or so I turn it back on and there seems to be a lot of air in the system, is this normal?

    Thanks

  • #2
    Re: Boiler expansion tank

    water coming out the schrader valve on the expansion tank sounds like the bladder burst. Time for a replacement

    the air in the system is the hydrogen and oxygen separating in the system, it's normal but dangerous, bleed all that air out before using anything like the dishwasher.

    also, turn off the water heater/boiler when you leave for the week, that should prevent the gas separation
    No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

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    • #3
      Re: Boiler expansion tank

      Why did you depress the schrader to begin with? Just curious.

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      • #4
        Re: Boiler expansion tank

        Just to see if there might be water in it. because the relief valve seems to spurt out water once in awhile.

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        • #5
          Re: Boiler expansion tank

          Why do you shut the water off?

          Are you leaving the boiler on to maintain temperature in the house so pipes don't freeze?

          If yes then you need to keep a supply of make-up water to the boiler. If you shut off the water supply to the house, once the pressure is bled off in the system there is no water for the boiler. Also, the boiler pressure can now easily overcome the house pressure once it drops can this can cause a back pressure condition which could contaminate your drinking water.
          "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
          John Ruskin (1819 - 1900)

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          • #6
            Re: Boiler expansion tank

            Originally posted by churchi View Post
            Just to see if there might be water in it. because the relief valve seems to spurt out water once in awhile.
            Yes, the relief valve is doing its job. Since the bladder in the expansion tank has failed and the tank is waterlogged there is no room for expansion so the relief valve pops when the system pressure gets high (above the setpoint of the relief valve).
            "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
            John Ruskin (1819 - 1900)

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            • #7
              Re: Boiler expansion tank

              Originally posted by Bob D. View Post
              Why do you shut the water off?

              Are you leaving the boiler on to maintain temperature in the house so pipes don't freeze?

              If yes then you need to keep a supply of make-up water to the boiler. If you shut off the water supply to the house, once the pressure is bled off in the system there is no water for the boiler. Also, the boiler pressure can now easily overcome the house pressure once it drops can this can cause a back pressure condition which could contaminate your drinking water.

              Hopefully the boiler is installed to code and has a backflow preventer.

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              • #8
                Re: Boiler expansion tank

                Originally posted by churchi View Post
                Just to see if there might be water in it. because the relief valve seems to spurt out water once in awhile.

                I see, good call. Are you going to replace the tank? If you do don't forget to check the pressure in the tank on the air side.

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                • #9
                  Re: Boiler expansion tank

                  Originally posted by EverettsPHAC View Post
                  Hopefully the boiler is installed to code and has a backflow preventer.
                  My point exactly, but I don't trust BF devices 100%. They are the last line of defense, unfortunately some times they are also the only defense.
                  "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
                  John Ruskin (1819 - 1900)

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                  • #10
                    Re: Boiler expansion tank

                    I certainly am going to replace the tank, they come fac. charged at 12 psi I believe, also the loop is filled with Glycol because of the cold temps in Northern NH so I am not sure how the water makeup valve would be adding water to the closed loop, system is equipped with a back flow device.

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                    • #11
                      Re: Boiler expansion tank

                      Originally posted by churchi View Post
                      I certainly am going to replace the tank, they come fac. charged at 12 psi I believe, also the loop is filled with Glycol because of the cold temps in Northern NH so I am not sure how the water makeup valve would be adding water to the closed loop, system is equipped with a back flow device.
                      I check every tank I change and many are wrong. Never hurts to double check before you turn it all back on.

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                      • #12
                        Re: Boiler expansion tank

                        Makes sense, if anything can go wrong it will, I wonder if that could have been the problem when it was installed,system always seemed to have high pressure around 30 psi and the relief valve is set at 30psi

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                        • #13
                          Re: Boiler expansion tank

                          Originally posted by churchi View Post
                          Makes sense, if anything can go wrong it will, I wonder if that could have been the problem when it was installed,system always seemed to have high pressure around 30 psi and the relief valve is set at 30psi
                          Check the PRV on the make up line.
                          "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
                          John Ruskin (1819 - 1900)

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                          • #14
                            Re: Boiler expansion tank

                            Expansion tank a gonner, everytime the boiler comes on it expands the water 5% and causes the pressure to rise above 30 PSI and blows out the T&P valve. Replace the tank quick or you will be replacing the boiler soon too.
                            ANYONE CAN TAKE THE HELM WHEN THE SEA IS CALM.

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