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  • Water hammer

    One of our service tech's has been dealing with a water hammer issue on a house for a few days now.
    the House has one meter. the incoming line pressure is 120psi, the line Tee's in the yard, one side going to an irrigation system with a double check valve. The other side of tee runs to the house.

    Heres where the problem starts.
    The company that piped the house, came back in and installed a PRV behind an access panel in the wall where the pipe enters the house. Since then, anytime the irrigation zone kicks on the water hammer is terrible, it hammered again when the irrigation system kicks back off. Now, our tech made sure that the pipe was strapped thoroughly, made sure an expansion tank was installed, and even cut in a hammer arrestor just before the PRV.

    All of this reduced the hammer when the irrigation system shuts off, but it still hammers violently when the system turns On.

    Does anyone have any thoughts? All I was able to suggest was moving the PRV/adding another one, at the meter so it protects the irrigation system And the house, but i'm not sure thats the right solution.
    No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

  • #2
    Re: Water hammer

    Does the hammering happen continuously when the irrigation is on or is it an initial thump? Does it happen on one particular sprinkler zone? Is there space to install a regulator near the double checks and have you tried throttling down the ball valves to see if the noise will go away just as a test?

    Comment


    • #3
      Re: Water hammer

      Are the irrigation system sprinklers on solenoids?
      If so can you trial and error one bank at a time and try and eliminate a bad one?

      Comment


      • #4
        Re: Water hammer

        Also, can you ID the PRV by manufacturer and model. This could also be helpful in diagnosing the problem.
        ---------------
        Light is faster than sound. That's why some people seem really bright until you hear them speak.
        ---------------
        “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
        ---------
        "Its a table saw.... Do you know where your fingers are?"
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        sigpic http://www.helmetstohardhats.com/

        Comment


        • #5
          Re: Water hammer

          the sprinkler system does use solenoid valves, do you think one of those is the problem?
          I'll have to ask if the tech if their are ball valves in for us to play with on that.
          from what he described, it's just an initial hammer when the system starts.
          Theres no room for a prv at the double check, thats why we were thinking of adding another one in the meter pit, so it would catch the irrigation system too. we could max out the first one at around 80, and keep the interior one set at 50 or so.

          The model of the interior PRV is part of the concern with the amount of water hammer, it's a Cash Acme Sharkbite PRV, if water hammer can damage good soldered fittings, it leaves me wondering how much a sharkbite can take.
          No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

          Comment


          • #6
            Re: Water hammer

            You say the pressure is 172psi that`around 850kpa if you bring the pressure down to 500kpa 73psi you will aliminate your water hammer solinoids cause water hammer as they open and close so fast not allowing the water in the pipe to stop gently causing water hammer also make sure that all the taps in the house have no floating valves and washers make sure the taps over the washing machine in the laundry are always turned off when not in use

            Tony

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            • #7
              Re: Water hammer

              well, 120 is the line pressure, that's why the PRV was installed originally. I've heard of water hammer with quick closing valves before, it's just always been when the valve Closes, not when it opens, which is the case here.
              No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

              Comment


              • #8
                Re: Water hammer

                What's the recommended operating pressure of the irrigation equipment?

                120 psi seems too high

                Let the irrigation company deal with it

                Comment


                • #9
                  Re: Water hammer

                  This is honestly probably the best solution, I appreciate the responses guys.

                  Originally posted by plumberscrack View Post
                  What's the recommended operating pressure of the irrigation equipment?

                  120 psi seems too high

                  Let the irrigation company deal with it
                  No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

                  Comment


                  • #10
                    Re: Water hammer

                    Why would You run 120 for the Irrigation ? RE plumb to 60 lbs
                    I can build anything You want , if you draw a picture of it , on the back of a big enough check .

                    Comment


                    • #11
                      Re: Water hammer

                      i'm not entirely sure what their logic was, but in our area it's common to have the PRV in the house and leave the irrigation system unprotected.
                      then again, that golf community is one of the few places i've been with that kind of line pressure.
                      No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

                      Comment


                      • #12
                        Re: Water hammer

                        For what its worth adding a prv at the meter seems like the most logical solution to me.

                        Comment

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