Water Hammer Mystery

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by DIYorBust, Nov 27, 2020.

  1. DIYorBust

    DIYorBust Active Member

    Joined:
    Mar 5, 2019
    Location:
    Long Island, New York
    Today my wife was taking a shower and suddenly we had a massive continuous water hammer in the hot water line. We have never had that before in this house. She told me it stopped when she opened a lav valve to wash something while the shower was running. Any idea where to start investigating? We are on municipal water.

    Thanks!

    DIY
     
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
    Sep 2, 2004
    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
    What type of valve is there in your shower? If the valves use a conventional washer, the washer may have become loose, and it's vibrating. Some debris in the line can sometimes do that. Some tub spout diverters can make some nasty sounds once their seals start to harden and wear out. Changing the flow by turning on another faucet can affect the flow volume and potentially the dynamic pressure as well, which can change the water velocity enough to stop the effect.
     
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  4. DIYorBust

    DIYorBust Active Member

    Joined:
    Mar 5, 2019
    Location:
    Long Island, New York
    Thanks for your reply! This is a 1920 with very old valve stems with washers. I've changed out most of the stems, but with dread, as I like the original tilework and fixtures. Luckily, the old builder did position a closet behind the showers with a partial access panel, so good on them. If it were 50 years ago, I'd honestly try to send the original builder a bottle for that.

    I am strongly considering redoing the shower valves with a delta thermostatic when I get some time. The shower looks to me like a retrofit, and the original was likely a tub only. The tilework comes only up to 50 odd inches or so. The area above is painted beadboard and has apparently held up for at least 30 years.

    Anyway I'll try pulling that stem, and see if I can't sort this out! Will post back with the result. Thanks.

    DIY
     
  5. Wisciherb

    Wisciherb New Member

    Joined:
    Dec 2, 2020
    Location:
    Wisconsin Dells, WI
    Are you on city water or a private well and pump system?
     
  6. DIYorBust

    DIYorBust Active Member

    Joined:
    Mar 5, 2019
    Location:
    Long Island, New York
    I have town water supply. The house was on well supply originally but converted probably 20-30 years ago. How are you thinking this would this affect my issue?
     
  7. Wisciherb

    Wisciherb New Member

    Joined:
    Dec 2, 2020
    Location:
    Wisconsin Dells, WI
    I work on private wells and pumps and when the pressure tank gets waterlogged it causes the pump to cycle on and off in rapid succession called "short cycling". With public water it could be a pressure regulator located where your water enters the house or the shower valve itself, with the shower hammer happening listen and you may be able to locate the source. Hope this helps.
     
  8. DIYorBust

    DIYorBust Active Member

    Joined:
    Mar 5, 2019
    Location:
    Long Island, New York
    Thanks, it is only one fixture and while the hammer can be heard all the way along the pipe run, I believe the source is the shower. Not certain though.
     
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