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Thread: Humming Pipes

  1. #1

    Default Humming Pipes

    Help! We have a humming noise in our pipes, sounds like a fog horn. Searched the internet and came across this.
    "Shut off main valve, turn on water inside house, flush toilets and then slowly turn back on main valve."

    That didn't work. There is also something my husband called a relief valve the builder put in but he can't remember what the builder said it was for. He tried to open it fully and close it but that doesn't seem to make a difference.

    Any suggestions would be appreciated.


  2. #2
    DIY Senior Member SteveW's Avatar
    Join Date
    Feb 2005
    Omaha, NE


    When does the foghorn blow?

    For example, is it at night, when the water is not running?

    Happened to me - it turned out to be that after I added a pressure reducing valve, it caused the house piping to be a "closed" system. Under those circumstances, when the water heater heats cold water and makes it warm, the newly expanded water has no where to go, and can create all sorts of loud noises as the pipes expand.

    If that's the problem, the solution is to install an expansion tank. Do a search on this site - it is discussed often.

  3. #3

    Default Additional Information

    Sorry, the noise happens when we either run hot or cold water or flush the toilets. Seems to happen with all running water in the house. My husband just told me we have an expansion tank.

  4. #4
    DIY Senior Member Mike Swearingen's Avatar
    Join Date
    Jan 2005
    On Albemarle Sound In Northeastern NC


    Replace the toilet water tank inlet valve(s) with Fluidmaster 400A float-cup types. They only cost about $5-$7 bucks at a big box and come with easy illustrated installation instructions. Should solve your problem.
    Good Luck!

  5. #5
    Plumber patrick88's Avatar
    Join Date
    Sep 2007
    Webster Ma.


    I would check each knob style shut off in the house, before i spend any money on anything else. The washers tend to come loose and will vibrate when water passes over them. I would change all old shut offs to new 1/4 turn ball valves no rubber to make noise when old
    I'm just starting to work with an old friend of mine to bring solar electric and hot water systems, wind turbines, Flex Fuel Boilers, batteries, hydroponic gardening, books, pellet grills and more. Also the parts for DIY installation.

  6. #6


    I agree with Mike S.

    Try to isolate the problem by turning off the toilet stops one at a time. When the noise goes away, you'll know which toilet fill valve to replace.

  7. #7
    DIY Junior Member vmplumbing's Avatar
    Join Date
    Jul 2006


    i've solved this problem by actually replacing the old pressure reducing valve.

    and, it's always a good idea to install an expansion tank when installing or replacing a PRV.

  8. #8
    Homeowner geniescience's Avatar
    Join Date
    Nov 2005
    humid summers hot, humid winters cold

    Default diagnose first, replace after you know

    i won't disagree with the suggestion to change to this or that... It could be a valve. You said this only happens when water moves.

    a,) "knob style shut off" --- that is a valve
    b,) it could be the toilet water tank inlet valve.
    c,) or even a pressure reducing valve.

    All are valves, and all can be happily replaced with the newer and better alternatives suggested. Turning off valves and "seeing what happens" is a scientific process of methodical trial and error, assuming you keep track of the permutations and combinations. This will help you isolate the most probable causes, and eliminate some of the possibilities too.

    Post what you find out.



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