Water hummer

Discussion in 'Plumbers' Talk' started by Kyy1, Dec 7, 2021.

  1. Kyy1

    Kyy1 New Member

    Hello, I have been having water hammer after flushing toilet in the past couple of weeks. I have tried turning off the stopcock and opened all taps to drain all the water in pipes and toilet then turned the stopcock back on for 2 to 3 cycles. The water hummer then fixed for a few flushes but it comes back.

    It's ok a few weeks ago before we fixed the bath tap which required to turn the stopcock off and back on. Or is it the problems with the push button flush unit needs replacing as it's 4 years old.

    Thanks.
     
  2. pppmacca43

    pppmacca43 Super Member

    I had recently a flush valve that was constantly letting water trickle into the pan so the fill valve was opening intermittently, each time the fill valve opened and then shut off it would send a shudder through the pipes. obviously yours is only doing it after flushing so I assume your flush valve isn't letting by. Normally you can replace the fill valve and it will cure the issue. do you have a picture of your current fill valve in the cistern? Also quite often you can manually push the fill valve up and down and get it to make the noise. It may also be your stoptap wasn't fully open before and needs dialling back a bit further.
     
  3. Joe the Plumber

    Joe the Plumber Screwfix Select

    It could be the washer has come loose in your stop tap as a result of turning it off (if it's old, they sometimes do that). That would resonate throughout the house.

    If you've got another loo, try that one and see if it also does it. That will point to the stop tap. If not, it may be the push button loo you mention.
     
    Last edited: Dec 7, 2021
  4. Kyy1

    Kyy1 New Member


    Please see the image attached.
     

    Attached Files:

  5. pppmacca43

    pppmacca43 Super Member

    When u manually push the blue float on the fill valve up and down can u make it make the noise. Float valves are a common cause of water hammer, the one I changed a couple of weeks ago, it cured the issue.
    That’s what I would be looking at first.
     
  6. Kyy1

    Kyy1 New Member

    Yes, I can hear the noise when I manually push the blue float on the fill valve down. Is it the problems with the toilet valve?
     
  7. pppmacca43

    pppmacca43 Super Member

    Obviously without seeing it I couldn’t 100% guarantee it but that is certainly the first thing I would be looking at changing. Probably for a fluidmaster pro fill valve or a Dudley hydroflo fill valve. I’d use the flow restrictor that comes with them too.
     
  8. Joe the Plumber

    Joe the Plumber Screwfix Select

    I gave up using the restrictors with Fluidmaster Pro 45s years ago. After about a year, they begin to squeal when refilling, which is often worse than the problem they were fitted to solve.

    If a new valve doesn't solve it (and remember it started when you turned the stop tap off to repair a bath tap, nothing to do with the loo), please see my first post, above.

    I'd also try turning a mains cold tap on and off quickly a few times before you fiddle with the loo to see if that provokes the noise. If it does, it's not the loo.
     
    just pumps likes this.
  9. Kyy1

    Kyy1 New Member

    I have just tried turning the stopcock on and off quickly a few times and then I flushed the toilet again, still has noise.
     
  10. Kyy1

    Kyy1 New Member

    Thank you. I will order a fluidmaster pro fill valve. I haven't yet tried replacing one of those before.
     
  11. Kyy1

    Kyy1 New Member

    The main stopcock was replaced 4 years ago and the washer was replaced a few months ago without any issues. Thanks
     
  12. pppmacca43

    pppmacca43 Super Member

    Obviously isolate water, and ensure unit has stopped in the cistern. Flush the cistern to empty it. There will be some residual water in the bottom of the cistern, I use a wetvac to get it out but a sponge works well.
    Disconnect the fill valve from the pipework and then undo the nut to take out the fill valve, bear in mind a little water will probably come out so maybe put an old towel down.
    Clean around the hole removing any mastic etc. and then put the new valve in with the rubber washer on the inside of the cistern. Put the flow restrictive supplied up the brass threaded shank. Tighten nut up on brass thread to fit tightly in cistern before redoing pipework to the thread and tightening. Turn on and check all is working and water tight.

    I will quite often put the fillvalve through and then ‘caulk’ around the thread underneath, where it goes thru the cistern with sanitary silicone before tightening the nut on. Belt and braces, and with the fluidmaster the main working mechanism is replaceable from the top so the bottom part won’t need to be disconnected again.
    You may also need a new fibre washer depending on the connection from the pipework to the valve.
     
  13. Kyy1

    Kyy1 New Member

    Thank you for explaining to me! Appreciated. How often do you need to replace the fill valve? I think the one was replaced less than 4 years along with the whole push button stuff.
     
  14. pppmacca43

    pppmacca43 Super Member

    Depends, sometimes they last years and sometimes not so long. Hard water areas normally they won’t last as long. The beauty of the fluidmaster is it comes in two parts so will take seconds to change in future should it be needed
     
  15. Kyy1

    Kyy1 New Member

    It doesn't resolve the issue. In fact, it gets worse. the water hummer get stronger with the new valve. The noise comes during refilling and finished refilling rather than just finished refilling. I have turned the stopcock higher to allow the water come in quicker then it seems to improve a little bit
     
  16. pppmacca43

    pppmacca43 Super Member

    Maybe the stoptap is playing up as Joe suggested, could be a loose jumper or washer. It was worth trying the fill valve tho as this is a common cause. You may need a plumber to try and diagnose, seems strange it only happens on this toilet.
     
  17. Kyy1

    Kyy1 New Member

    Have a plumber came and spent an hour but didn't know what was the problem. He tried to turn up and down the stopcock but doesn't work. He said the noise is annoying but it shouldn't damage the pipes as it's not like a massive banging. Just a little bit at the end of each flush and I will soon forget about this noise. Not to comfortable with his response and will try find another plumber.

    I'm not sure if it's something to ignore.
     
  18. pppmacca43

    pppmacca43 Super Member

    It won’t cause any damage, but agree it’s annoying and u want to get sorted. Noises can be difficult to diagnose and sometimes it’s a matter of trial and error when replacing parts or carrying out works.
     
  19. Kyy1

    Kyy1 New Member

    It's very helpful to know it won't cause any damage. Have been calling plumbers yesterday but all of them are fully booked before Christmas and none of them were keen to check out water hummer issues.

    If it won't cause any damage I may leave it as it's quite expensive to even call out charge.

    Thanks pppmacca43
     

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