Perplexing water hammer issue

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by TRK, Sep 7, 2020.

  1. TRK

    TRK New Member

    Joined:
    Sep 7, 2020
    Location:
    Milwaukee, WI
    Hello,

    I have a water hammer issue that I haven't been able to find on this forum, or elsewhere on the internet.

    *The hammer occurs on the 2nd floor near/between two bathrooms.
    *The hammer is easily triggered by turning off either the hot or cold of any faucet, or any bathtub (anywhere in the house, but most notably in the second floor bathrooms).
    *A plumber installed additional arrestors at the 2nd floor bathroom lines (issue back within a few on/offs of any faucet).
    *I have tried the system drain / refill procedure many times (issue back within a few on/offs of any faucet).
    *I have replaced the single-handle cartridges in both bathtub showers on the second floor (issue back within a few on/offs of any faucet)
    *Removed flow limiters before shower heads (no effect, just did in case)

    I'm at a loss. Since the issue comes back before I have run the dishwasher/laundry, it seems unlikely I'd need to work with those devices.

    Possible next ideas:
    *Cartridges for double handle faucets?
    *Toilet?
    *Shower diverter / spout?
    *Cheap, 10-15 year old Pegasus shower and sink faucets, but I imagine it's expensive to replace the shower ones with the tiling, etc.

    Thank you for any advice- being hot and cold, and so easily produced makes this perplexing to me.
     
  2. Jeff H Young

    Jeff H Young In the Trades

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    PSI of incoming water? Sounds like real high pressure and sloppy loose pipes.
    If every fixture does this I dont think its every shower valve every toilet and every lav and sink have all gone bad at same time thats redicules
    Few more questions When did you move in this house? Did you just wake up one day and this suddenly happened? How long has problem been going on? You hired a plumber and he installed arestor The other stuff in parethesis I cant understand? which type of pipe is in house pex copper cpvc galvinised? does house have a pressure reducing valve? What did your "plumber " recomend or think could have been problem? If you can answer all these questions it would help.
     
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  4. WorthFlorida

    WorthFlorida The wife is still training me.

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    Orlando, Florida
    Usually when water a valve is closed very fast you hear the bang. Have your tried slowly turning off the water at any fixture? One trick you can try, at the main shut off close the value most of the way. This will not reduce pressure until water is running. For this test run water at sink or tub and adjust the shut off valve until the water is flowing where you can reasonably accept the flow rate. Then turn off the water first rapidly then slowly. I expect that there will be some thumping noise and the pipes should hardly rattle. If everything did quite down then you are working with high pressure and a PRV maybe needed. An expansion tank on your water heater, if you have one, will help but it won't cure it completely.

    If you feel that it may be caused by a faucet or an appliance, turn off the water at all sinks, washing machine, dishwasher, etc. At one working faucet test if there is water hammer. Try it at different locations. If the hammer still occurs it is not a faucet issue. Do as Jeff Young suggest, get a reading on your water pressure.
     
  5. TRK

    TRK New Member

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    Sep 7, 2020
    Location:
    Milwaukee, WI
    Thanks, gents.

    I'm not sure the incoming PSI. I live in a medium sized city and assumed it'd be okay (but can test Worth's idea of partially closing the incoming valve).

    Answers to Questions:
    -Lived in this house 11 years, noticed problem for last 1-2. House was built in 1974.
    -Copper pipes
    -Plumber installed the arrestor and, when it didn't solve the problem, said he would have next replaced cartridges but didn't have the right ones with him.
    -I don't think we have a PRV
    -My comments in the parenthesis meant this: I can temporarily get rid of the hammer by doing various things (e.g., a whole-house drain and refill). However, if I quickly close a faucet a few times, the hammer comes back again. By the end of the day, the hammer is back to full intensity again no matter what I have done.


    Questions for my own knowledge:
    1. My assumption was that a bad valve anywhere can let air into the system, whereby closing any valve anywhere can then trigger the water hammer (even if the valve being closed is itself fine). Is this not the case? I can trigger the hammer by quickly closing any faucet in the entire house (as long as I'm near the 2nd floor to hear it).

    2. What is the theory with turning off one fixture? I can try this, just trying to understand. Is it that my understanding of question #1 above is correct (that a bad valve introduces air into the system), and we're trying to prevent this from happening?

    Thank you for your insights! I'd have the plumber come back, but at this point I feels like a time-consuming trial and error endeavor (would cost a fortune).
     
  6. Reach4

    Reach4 Well-Known Member

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    Location:
    IL
    Garden hose thread pressure gauges are widely available, and under $20. Maybe substantially under.

    Connect to hose spigot, laundry tap, or drain on water heater.
     
  7. Jeff H Young

    Jeff H Young In the Trades

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    Thanks you helped with additional info. I agree the trial and error on these problems are costly very costly.
    My first recomendation almost never changes check pressure so you can get an inexpensive test gauge for about 15 bucks. No one ever wants to buy one but I would.
    Bad cartridges sucking air in ? I dont know of such problem like to hear if others agree.
    If you can place yourself in attic , basement or where ever pipes are you might be able to grab hold of pipe see if its loose while some one duplicates the noise.
    Also you did say every faucet , toilet, and shower right?
    BTW removing flow restrictors greatly increases possibilty of water hammer. You may want to re install.
     
  8. WorthFlorida

    WorthFlorida The wife is still training me.

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    Location:
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    Air does not cause hammer, if anything is helps reduce it. If air does get in it will usually rise to the highest point. When a faucet is opened near it it will bang because the air is rushing out. In my house the one toilet upstairs will scare the crap out of you when I have to turn off the water to open a pipe. When you flush the tank lid jumps.

    maybe I was miss understood. Close all valves at all the fixtures except one. Run the water for your hammer test at the fixture. Do this for all fixtures. If will prove that none or one faucet is the problem big I doubt any of them will be the cause.
     
  9. TRK

    TRK New Member

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    I'll buy a gauge and report back with incoming line pressure.

    Yes, I can trigger the water hammer using any faucet in the house. I don't know that the toilets trigger it - they may not close fast enough.
     
  10. Jeff H Young

    Jeff H Young In the Trades

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    agree Air can cause a sputtering but air in system will cusion a water hammer
     
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Let's make sure we're talking the right things.

    When anything is moving, it has inertia...it wants to continue to move the same way. Just like hitting a brick wall, that rapid stop can be problematic. With the water flowing, when you close a valve, if the pressure is higher, the velocity of the water is higher, so that's the first thing to check. If that's within specs (NGT 80psi), then the next thing is a pipe that is not anchored well, especially when there's an elbow involved...the water tries to keep moving the way it was, and hits a wall at the elbow, and that can move the pipe up against some object and literally hammer it.

    Most valve don't close fast enough to be that big of a deal, but some, especially things like ice makers, washing machines, dish washers that all use solenoid valves (quick acting) to shut off the water, that can create a hammering effect.

    Most valves can't be turned off fast enough to create a hammer, but there are some. If you follow their installation instructions, they'll tell you to add hammer arrestors, but that's not common.

    A loose washer can vibrate if you're dealing with some valves. The solution is to tighten up the screw holding the washer to the stem. The thing that is common to all of your water is the main shutoff, so that could be a place to start. But, that symptom is more of a hammer while the water is running, not when it stops.
     
  12. Jeff H Young

    Jeff H Young In the Trades

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    bad washers can cause it usually they rattle like a machine gun when water is running not just a single bang when closed.
    Also the symptoms described I dont suspect a bad washer as it bangs when any fixture is turned off except toliets
    Im wondering how his pressure test comes back if it will be excessive.
     
  13. TRK

    TRK New Member

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    Thanks everyone. I'm waiting on the arrival of my pressure gauge and will report back once I have the finding.

    New addition: beyond hammering when quickly turning off hot or cold sides of any almost any faucet in the house, I can also trigger a hammer when I turn the hot side of the nearest sink on.
     
  14. Jeff H Young

    Jeff H Young In the Trades

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    that senario is common to hear when opening a faucet as well usually not as loud.
    flow restrictors or water saver shower heads reduce hammer when installed .
    Medium city, big city no bearing on your water pressure.
    Something changed and sudenly created a problem.
    I will say symptoms are classic examples of 3 things 1 high pressure 2 poor strapping 3 undersize piping. there are many other possibilitys and likely hoods and its possible none of these 3 the leading factor. but Im not one of the guys that belives 80psi is ok either unless you want hammer so im hoping its under 60psi
     
  15. TRK

    TRK New Member

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    Finally got the gauge and measured exactly 60PSI at the outdoor spigot. I assume this means pressure is on the upper end of normal?

    I'm not sure if this helps, but is it noteworthy that the hammer sound happens in the same spot no matter which faucet is closed? It makes sense to me that it'd always be at the highest spot in the house (which is the case here), but maybe it provides some insight.
     
    Jeff H Young likes this.
  16. Jeff H Young

    Jeff H Young In the Trades

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    Thats is a normal reading . I wouldnt be looking at installing a regulator . The guage will come in handy for general purposes like checking to see if pressures get excessive or low during certain parts of day.
    I think you mentioned removing water savers restrictors? removing increases water hammer . so might try re installing. which fixtures cause the most hammer?
     
  17. Reach4

    Reach4 Well-Known Member

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    Could you describe the sound that you hear? When does it occur-- single bang when you turn something off, or the toilet fill valve shuts off, plus a single bang when you turn on that one hot? No machine-gun sound?
     
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Water hammer occurs when the water is moving and you shut off a valve quickly...it wants to continue to move, (inertia) and when it hits the valve that stopped it, it can literally force the pipe to move, banging into something if it is not restrained. That water column stopping can bounce back and cause an issue away from the valve, too. But, water hammer typically doesn't occur when starting water flow. If you get a bang then, it's probably something else.
     
  19. Jeff H Young

    Jeff H Young In the Trades

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    ok let us know what you try I made a few suggestions .
     
  20. TRK

    TRK New Member

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    Location:
    Milwaukee, WI
    Answers to Questions:
    • Hammer sound detail
      • Primarily a big bang, followed by 1 medium, then 1 quiet
    • Triggering details
      • Most noticeable when quickly shutting off a sink/shower
      • Can also be triggered turning on the hot water in one of the upstairs sinks
    • Most-offending faucets
      • The two upstairs sinks are the easiest to trigger the hammer
      • I also notice a lot with the main floor kitchen sink (or upstairs showers/baths).
      • I did re-install the restrictors on the two showers; may have reduced hammer when shutting these off
    New Question:
    1. I assume the restrictors on the showers would only impact hammer when shutting off those valves, right?
    2. One toilet takes a really long time to refill. I don't notice hammer with this refill, but could this have anything to do with problems in the system?
    3. What is it about a valve that makes it "bad" from a hammer perspective? Debris/etc. makes it so that it effectively closes very quickly?
     
  21. Jeff H Young

    Jeff H Young In the Trades

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    1, yes and same for cartridges wouldnt ever cause hammer at say a lav or kitchen faucet. that I can think of
    2 probebly not the toilet most likely not the cause of water hammer at all other fixture
    3 many times its the inheirant desighn of a valve that is quick closing.

    Im assuming that no work has been done to the water system that you havent mentioned. sometimes a blockage a rock or something in the main line can be restricting flow so when water demand is high presure drops withen system and valve closed hard can really cause a hammer as can undersize pipe and long runs. its not always a easy thing to find. loose pipes another possibility. a lot of theory and guess work Ive done these jobs with other guys and supervisors guessing arguing our opinions people come up with Ideas one guy says its dumb another says try it. I never tried performing a pressure drop test and dont know really how to perform it or what readings should be but Im leaning toward a blockage somewhere , Hope this makes sence that this theory isnt flawed .
     
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