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screeching noise from water line

Discussion in 'Irrigation' started by justgeorge, Sep 21, 2007.

  1. justgeorge

    justgeorge LawnSite Senior Member
    Messages: 353

    Hey guys (and gals),
    Replaced an old Nelson valve with a Hunter PGV valve. Happens to be on zone 1 of the system. Now when it kicks on at 4:00am the homeowner gets a terrible screeching noise from the water line for 5-15 seconds. I went over there today to hear it and yep it would wake me up too. I'm guessing it's because the new valves are slower opening and until the valve is full open for some reason that is causing the screeching noise.

    The POC is in the basement, with the T below the pressure regulator for the house and just after the water meter. Then the 3/4" copper turns and goes vertical where it is anchored to the wall. Above that I can't see due to it is in a finished basement. There may or may not be a second anchor before it exits the house thru the foundation at about ground level. The backflow is outside.

    Holding the pipe with my hands while the valve turned on did nothing to quiet the noise - it's not the pipe vibrating and it's not water hammer and it also didn't sound like it was coming from the meter.

    I use Hunter PGVs all the time and have never had this problem. My only thought is to put the foam insulation around the copper then blanket that with R-13 wall insulation just to try to quiet the noise.

    Anything other suggestions to try?

  2. WalkGood

    WalkGood LawnSite Bronze Member
    Messages: 1,910

    I would change the new valve guts before messing with foam and insulation. You do not want to "own" those kind of home improvements!

    First, check that the house main is all the way open. Also the feed valve for the irrigation.

    The older other valves do not screech?
  3. justgeorge

    justgeorge LawnSite Senior Member
    Messages: 353

    Yep house main is open and all irrigation valves wide open.

    Where do I buy a fast-opening valve? Seems like all the new valves pride themselves on being slow opening/closing to avoid water hammer. None of the older valves on this system give this noise. I had also replaced another valve on this system last year; it makes the same noise but is last in the cycle and doesn't happen till after everyone is up so they never mentioned it to me last year.
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,267

    Just for grins, try a flow-control bonnet on the noisy valve, to see if slower opening makes a difference. I've done installs where initial opening 'surges' caused a water meter to 'howl' - basically a water meter problem, as the inner plastic turbine was chattering until the flow rate dropped.
  5. Dirty Water

    Dirty Water LawnSite Fanatic
    Messages: 6,794

    What is the static and dynamic pressure of the water line?
  6. Shuvelin'

    Shuvelin' LawnSite Member
    Messages: 11

    I too have seen that, but as soon as I used the manual bleed screw to get the air off the top of the diaphragm the problem was solved. Air in the bonnet was the problem for me.

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