Pipes bang hard when cold water on full blast

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Carri, Oct 11, 2010.

  1. Carri

    Carri New Member

    Messages:
    4
    Location:
    USA
    This did not happen prior to our bathroom remodel. Only after our bathroom was redone did the pipes start banging when the cold was on full blast, but this only happened at the kitchen sink. The banging did not happen when you turned the water off. It was when the cold water at the kitchen sink was on full blast that it happened. The remodeled bathroom is on the second floor, not above the kitchen, and if you turned the cold on full blast at the kitchen sink, the pipes in the kitchen started banging really badly.

    So we got in touch with the contractor who redid the bathroom, and his plumber did not know why the banging was happening. He tried to remove air from the pipes but that did not solve the problem. Next he installed a vertical piece of pipe in the upstairs bathroom under the sink (picture one attached) but this also did not solve the problem. Now tonight he installed a different type of vertical piece of pipe in the kitchen under the sink (picture two) and this seems to have stopped the horrendous banging.

    It seems that these vertical pipe pieces (on the cold lines only) are a patch to the problem, which was not a problem before the bathroom remodel. Our plumber seems to want to blame our new Jado valve, saying that it causes too much pressure in the lines. We want to know why this banging happened in the first place (only the cold full blast in the kitchen) and whether these vertical pipe pieces make any sense. We do not want to have to drain the lines periodically so this alleged patch job continues to work.

    PSI is 65. Thoughts please? Thanks in advance.

    Picture One
    pic_1.jpg

    Picture Two
    pic_2.jpg
  2. dlarrivee

    dlarrivee New Member

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    Location:
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    The first chunk of copper is useless, the second is a proper water hammer arrestor.

    What happens if you regulate the pressure down to 50psi instead of 65?
  3. Carri

    Carri New Member

    Messages:
    4
    Location:
    USA
    Not sure how to change the PSI to 50 but if you turn on the outside garden hose and cold at the kitchen sink, the kitchen pipe banging seemed to stop. The thing is though that PSI 65 did not bang any pipes prior to the bathroom remodel. :confused:
  4. Redwood

    Redwood Master Plumber

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    There is either debris in the pipes or a loose washer on a valve somewhere...
  5. Carri

    Carri New Member

    Messages:
    4
    Location:
    USA
    Thank you for the replies. :) Four more questions please...

    Do you think it is possible to fix the pipe banging without the use of these vertical pipe pieces?

    If the upstairs vertical pipe piece is useless (picture one in first post) should it be removed?

    If these vertical pipe pieces stay in place, will we need to drain the lines periodically to prevent the banging from coming back?

    Could the pipe banging have been prevented in the first place?
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    A hammer arrester is an engineered device with a sealed air chamber (a piston or bladder - yours has a piston separating the air and water). It works until it fails, and that should take many, many years. The first one is an old school air chamber...open to the water, and very quickly all that air will disolve into the water stream as it passes, and be useless. Shutting and draining the lines usually won't restore the air (think finger over the top of a straw). SO, shortly, it will be come useless. It could stay, but it isn't doing anything.

    Water hammer is caused by moving water stopping rapidly, causing the pipe to continue to move via inertia until it hits something, like a hammer, and you hear the noise. A constant vibration is usually caused by either some debris bouncing in the pipe against something that is then restricting the flow, and the pipe then vibrates. As noted, if there is a valve with a loose washer, that washer can vibrate as water passes, changing the water flow, similar to some debris. You may have to remove the aereators from the faucets, maybe the cartridges, and the toilet fill valve then turn the water on to see if you can dislodge any debris.

    Make sure all shutoffs are fully opened, and if not 1/4-turn ball valves, you might want to consider changing them to that type (1/4-turn valves don't have traditional washers and have less restriction).
  7. Redwood

    Redwood Master Plumber

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    yes, it doesn't matter, no because it hasn't solved the problem, probably not
  8. hj

    hj Moderator & Master Plumber Staff Member

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    The real problem that what you describe is NOT conventional water hammer which occurs ONLY when a faucet or valve is closed suddenly. It does not happen while water is flowing, so we cannot tell what the cause was, or why the arrestor "cured" it.
  9. VernK

    VernK New Member

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    Kelowna, BC
    The arrestor, in this case, added a "spring" to the system and maybe luck just had it that it was just the right rate to damp the vibration
  10. Thatguy

    Thatguy Homeowner

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    If the arrestor works under all conditions can we say logically say that there are pressure waves in the system?
    Regarding "full blast", turbulence must increase with fluid velocity, right?

    Was the banging once per second, 5x per second. . .?
    Are the pipes clamped at the recommended intervals?
    Last edited: Oct 16, 2010
  11. Gsalet

    Gsalet George the Plumber

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    Location:
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    Don't forget about pressure balance shower valves with check stops, If debris gets in the stops it will cause the pipes to bang when anything is turned on randomly.
  12. Thatguy

    Thatguy Homeowner

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    So if the problem were debris the noise would have stopped anyway if the plumber just waited.
  13. hj

    hj Moderator & Master Plumber Staff Member

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    Debris is the least likely source of the noise and would have been evacuated as soon as the water was turned on and the faucets used, anyway.
  14. Redwood

    Redwood Master Plumber

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    Well it would stop if the debris/loose washer was flushed out or, removed...
    Right now the arrestor is dampening the pulsations that are still there or, the debris moved to where it is not a problem at the moment.
  15. Thatguy

    Thatguy Homeowner

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    I guess the next logical step is to buy a pressure gauge for a few bucks and see what it says.

    Also try turning off the water using a washing machine, which valves work very fast, and see if that brings back the banging.

    Try as many different ways as you can to bring back the problem so as to provide troubleshooting clues.
    Or hope that the problem never returns. Hoping is free, even in this economy.
  16. Carri

    Carri New Member

    Messages:
    4
    Location:
    USA
    Thanks for all the replies. Just thought I'd stop by and provide a follow-up. :)

    Unfortunately, the pipe banging described in the first post was not the only problem to arise. The new faucet in the bathroom started leaking (tee assembly area), the manufactured arrestor started leaking (connection end), and the shower valve started leaking (possibly cartridge). The first plumber also installed the shower valve incorrectly, the contractor shimmed it, but the valve was still crooked. We again got in touch with the contractor who redid the bathroom, and this time he sent out a different plumber (there were actually two that came).

    We had the new plumbers fix the leaky bathroom faucet, remove the hand-made arrestor, reinstall the shower valve, reset the toilet, and check the shower head. The latter two items were for peace of mind, given the problems that were happening. The new plumbers also wanted to install a different/new supply line to the toilet and a new shut off valve on the kitchen sink, to which we agreed. I also had them remove the manufactured arrestor from the kitchen sink just to see, once they were done, if the banging in the kitchen went away.

    As it turns out, the shower head was installed correctly. However, the toilet was seated incorrectly by the first plumber, with the wax ring dented in and not compressed correctly, the new plumbers said. They also said that the toilet wold have leaked as well. I did overhear the new plumbers talking about why I wanted the manufactured arrestor removed from the kitchen sink (maybe they thought I was being nuts) but as it turns out, after they were done with the work, the banging and leak were gone from the kitchen.

    Our suspicion is that the cause of the banging in the kitchen was due to the shower valve being crooked, but whatever the cause, the banging is now gone, no arrestors installed. Just for fun (really though this process has been anything but fun) here are a couple of pictures of the shower valve/trim before (first plumber) and after (second plumbers).

    Before:
    before.jpg

    After:
    after.jpg
    Last edited: Oct 19, 2010
  17. Thatguy

    Thatguy Homeowner

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    ******************xx
    Last edited: Oct 20, 2010
  18. Thatguy

    Thatguy Homeowner

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    So with all this new information, in retrospect, was the crooked shower valve the likely cause? Or, could it have been something as simple as adding or repositioning pipe clamps?

    I wouldn't be sure the banging is permanently gone until after a few days, at least.
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