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  • Water hammer/ expansion tank

    Hello,

    Incoming city water pressure varys 75-100psi, installed prv set at 60psi. Added t-12 expansion tank at 50 gallon water heater. Set air at 60psi. Ran 3/4" copper for outside hosebib about 30' I used Arrowhead ada 1/4 turn ball valve full port on the new line and replaced the one on the service entrance along with the prv. Did a bunch of other work, adding laundry, utility sink etc. All pipes are secure! When opening the new full port hosebibs front or back I'm getting real bad water hammer. If opened very slow no problem. When I reduced the pressure to 50psi problem lessened but still bad. Removed expansion and plugged, no water hammer problems. Expansion tank needs to stay and I'd like to keep the hosebibs rather than traditional no kink hosebibs. Do I neeed arrestors? Locations? I haven't run into this before. Expansion tank seems ok doesnt get water logged.??? Have a guage at expansion tank and double checked pressures, every thing right on the money.

    Thanks , wookie

  • #2
    Re: Water hammer/ expansion tank

    When exactly does the water-hammer happen and for how long?
    Water Heater Reviews & Water Heater Information

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    • #3
      Re: Water hammer/ expansion tank

      Only when opening the two new hosebibs for about 2-3 seconds but loud!

      thanks wookie

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      • #4
        Re: Water hammer/ expansion tank

        Install hammer arrestors on the hose-bibb lines after the ballvalves. It is weird that is goes away when the expnasion tank is removed, I don't think I have seen that before.
        Water Heater Reviews & Water Heater Information

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        • #5
          Re: Water hammer/ expansion tank

          One more idea to try, bleed out some air in the expansion tank, 60 psi of air is a bit excessive.
          Water Heater Reviews & Water Heater Information

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          • #6
            Re: Water hammer/ expansion tank

            This doesn't make sense to me. Can anyone answer this and teach me?

            J.C.

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            • #7
              Re: Water hammer/ expansion tank

              I know, Wasn't feeling to good with the customer standing right there. The hosebibs are ball valves. Installing a arrestor at sevice entrance not easy, no room without complete redo. Thinking about one near the expansion tank and at new hosebib.

              Thanks ,wookie

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              • #8
                Re: Water hammer/ expansion tank

                Pull the stems on the sill cocks and see if the bibb washer screws are loose.

                Comment


                • #9
                  Re: Water hammer/ expansion tank

                  Originally posted by wookie View Post
                  I know, Wasn't feeling to good with the customer standing right there. The hosebibs are ball valves. Installing a arrestor at sevice entrance not easy, no room without complete redo. Thinking about one near the expansion tank and at new hosebib.

                  Thanks ,wookie
                  I misread the original post.

                  Install a conventional hose bibb as opposed to a fast acting valve.

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                  • #10
                    Re: Water hammer/ expansion tank

                    The full port hose bibb's are acting like a fast closing valve. Are there vacuum breakers on it? take the vacuum breakers off, I had hammer on a hose bibb and I removed the vacuum breaker, it worked perfect, no hammer.

                    I would also take some of the air out of the expansion tank, try to get some cushion in the system.

                    Hopefully this helps. good luck and let us know how it turns out
                    sigpic

                    Robert

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                    • #11
                      Re: Water hammer/ expansion tank

                      Originally posted by Killertoiletspider View Post
                      I misread the original post.

                      Install a conventional hose bibb as opposed to a fast acting valve.
                      I was just about to suggest same thing. I misdread it also, until he re-explained.
                      Water Heater Reviews & Water Heater Information

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                      • #12
                        Re: Water hammer/ expansion tank

                        Many hose bibbs have different threads and won't allow a hose to be screwed on where the vacuum breaker was. Besides not code.
                        Buy cheap, buy twice.

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                        • #13
                          Re: Water hammer/ expansion tank

                          Does this happen when the washing machine is running?
                          Buy cheap, buy twice.

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                          • #14
                            Re: Water hammer/ expansion tank

                            Originally posted by gear junkie View Post
                            Many hose bibbs have different threads and won't allow a hose to be screwed on where the vacuum breaker was. Besides not code.


                            This was just to see if it solves the problem, then instead of all the other issues, if it did, he would just replace the vacuum breaker.

                            Diagnosis only......I guess should have pointed this out
                            sigpic

                            Robert

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                            • #15
                              Re: Water hammer/ expansion tank

                              Water hammer is a pressure surge or wave resulting when a fluid in motion is forced to stop or change direction suddenly (Momentum Change). Water hammer commonly occurs when a valve is closed suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe.
                              These are bellows type expansion joints taken from a medium-pressure (150-300 psi) steam line. They have been destroyed due to steam-generated water hammer, probably in excess of 5000 psi.

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