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Pipes thumping when sprinklers run.

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  • Pipes thumping when sprinklers run.

    I just had my house repipe with copper, now when the sprinklers run I hear a constant rythmic thumping, this happens both on the ones with electric valves and the manual one.
    Any idea what this could be and what can be done to fix it?

    Old pipes use to run in the concrete slab, new ones run overhead in the attic.
    The water preasure is about 70 PSI.
    The sprinklers are hook up before the shut off valve for the house. (When valve is shut off to house noise goes away)

    Thank you.

  • #2
    Re: Pipes thumping when sprinklers run.

    When your pipes were under ground that offered a good insulation of the pipes and there were "clamped" down by earth and concrete.
    But now you lost all that. The pipes should be insulated and clamped down good. And you can also install a anti hammer charged cylinder. It seems like the plumber would have clamped and insulted the pipes and codes around here call for the anti hammer cylinder for all systems that have solenoid controlled valves, like washer machines, dish washers etc.
    The noise of the sprinklers can travel though water so maybe just the insulation and clamping down pipes will solve your problem..


    • #3
      Re: Pipes thumping when sprinklers run.

      Check your vacuum breaker valve for the sprinkler system, make sure it is not source of thumping, it can oscillate open/closed if not sufficient pressure/volume after the re-pipe, might explain why shutting house valve makes thumping go away.


      • #4
        Re: Pipes thumping when sprinklers run.

        could be a few things. as mentioned it needs to be both isolated from the wood structure and yet clamped to prevent hammering when shut off quickly. not so tight that the insulation/ isolation is useless.

        the other issue could be that the water is flowing so fast now with the new copper that the meter is causing a noise as the paddles move that measure the flow.

        try adjusting the water flow down on the sprinkler valves and see if it gets quieter and still maintains enough flow to properly water the lawn.

        copper is also louder than steel pipe.

        phoebe it is


        • #5
          Re: Pipes thumping when sprinklers run.

          I have run into this problem on many occasions and a solution that we discovered that sometimes worked was to totally insulate the cold water line in the attic. This means that you will have to undo any strapping that is currently being used to secure the new piping to the wood framing. The new copper piping will transmit any and all noise through the wood. Using a 3/4" wall insulation you may be able to locate some big tube straps that will fit over the insulation.