Getting water hammer from downstairs flat. Advice needed please

Discussion in 'Plumbers' Talk' started by zenonithus, Oct 18, 2017.

  1. zenonithus

    zenonithus New Member

    Hello all,

    I have started getting some pretty bad water hammer noises when the flat below uses their water. There are two floors and I am at the top and we share the water main pipe as it runs up from their kitchen wall to mine.

    They have had a new washing machine and this produces a constant water hammer in my flat when it is used. When I turn off my lever valve at the mains the water hammering stops, so I'm thinking this is an issue I need to sort at my end.

    Here is a picture of where the mains water is coming into from the large iron pipe on the wall. I am renovating my kitchen and had the lever valve installed a month ago as well as an old valve taken out from the tap and essentially shortening the tap pipe. The banging I cant tell is coming from below the lever valve or just above it but that area in general.

    Also to note I loosened the plaster holding the main water pipe to the wall so it could be possible the pipe is looser. Though when I hold it tight the hammering continues.

    Also just to add I get water hammer when using my sink, bath taps and when the toilet stops refilling.

    pipes.JPG
     
  2. teabreak

    teabreak Screwfix Select

    Deleted member 33931 and KIAB like this.
  3. KIAB

    KIAB Super Member

    Full bore lever valve will not cause the hammering, as it has no washer plunger to bounce up & down.

    Inlet valve on toilet cistern might be worn, also don't rule out the taps.
     
    Last edited: Oct 18, 2017
  4. The Teach

    The Teach Screwfix Select

    A few pipe clips will also reduce the pipes bouncing around,if the rest of your plumbing and your neighbours plumbing is similar to the photo,good luck :(

    As mentioned by 'teabreak' the arrester is a must use item.

    On the off chance you may have very high inlet water pressure,this can give the same symptoms but try the above :)
     
  5. zenonithus

    zenonithus New Member

    Great thanks for the suggestions. I have been looking into an arrestor as this sounds like the only option in this case. Where abouts would be the best place to fit it in the image? Before or just above the stop lever?

    KIAB: would the flat below need their valves checked also? I still have no idea why when they shut their water off by tap or washing machine I am getting the hammer in my pipes?
     
  6. fillyboy

    fillyboy Screwfix Select

  7. The Teach

    The Teach Screwfix Select

    Traditionally they are fitted adjacent to the appliance causing the surge.

    You could fit on the inlet to your flat,you need some straight pipe to connect it so move the lever valve down and tee above and fit the arrester above.Add some pipe clips ;)

    15mm tee.jpg pipe clip white.jpg

    If the water hammer/knocking started after the new washing machine was fitted,the question should be directed to the installer.
     
  8. zenonithus

    zenonithus New Member

    Great, thanks for the suggestion. I cant move the lever down unfortunately as it will go below the kitchen unit. Maybe they can cut the pipe just before the tee where it is straight but at a slight angle and put it in there. Would also raise the tap to the level it was ;)

    Edit: actually that wouldnt work as its connected to the toilet water pipe lol! Ok maybe just replace that whole bendy pipe after the lever.
     
  9. The Teach

    The Teach Screwfix Select

    Yes and remember the pipe has to be rigid (supported with clips) to hold the weight of the arrester.
     
  10. zenonithus

    zenonithus New Member

    ok great. Might be best to plaster/fill in the wall behind first then for the clip ;) Any recommendations for a good arrestor that should last and take all the banging?
     
  11. The Teach

    The Teach Screwfix Select

    Clips not being close to the wall,use talon clips and talon clip spacers.

    The BES arrester listed is good but remember they are not designed for incorrect plumbing,in your or your neighbours flat.
     
  12. zenonithus

    zenonithus New Member

    cool, yeah there should be a bit of space between the pipe and wall for the talon. Still unsure what the people who fitted their washing machine could have done to cause the surge up to my pipes as their tap is also causing a hammer. Will need to see if I can speak to the people who installed the washing machine. Could they have increased the water pressure or anything like that for the new machine to work?
     
  13. zenonithus

    zenonithus New Member

    Hey all, I partially fixed this though I'm still having this issue :( I had a shock arrestor fitted just above the shut off lever valve and this fixed the water hammer at my end so no banging when I shut my taps or toilet refills etc. great! However, I am still getting banging when downstairs use their washing machine. The banging stops when I close the shut off lever at my end. I have attached a video of the banging noise at the main water pipe that feeds into the pipework in my first posted image. The bang is around every 10 -20 seconds when their washing machine is on.

     
  14. teabreak

    teabreak Screwfix Select

    Shock arrestors work best as near the source as possible, if you can persuade your neighbour to fit one near their machine it should do the trick.
     
  15. zenonithus

    zenonithus New Member

    Cheers teabreak, yeah I was thinking off offering to fit one or asking them to ask their landlord to fork out for one. They are pretty simple to fit from what I have seen. Do you think it has anything to do with the old iron pipe seen in the video? I was thinking could it have something to do with that old disused stopcock. I was going to get the pipe and stopcock removed and replaced with copper, though plumber said there is a risk it could break at the thread undoing that big nut behind the stopcock and that would introduce a whole world of pain having to replace the entire shared pipe right up to the loft :(

    Also how come they don't get this hammer and it stops when I shut off my water? Just wondering if this is something I need to fix at my end also
     
  16. teabreak

    teabreak Screwfix Select

    Well the shock arrestor you have fitted is now working on your leg of the supply, Water hammer is a regular subject for forums like these and hydraulic forces are unpredictable, all you can do is try things like arrestors if it is an appliance and sometimes changing stopcocks if they are suspect. The main cause is sudden shutting off of the supply, old style screw down taps are slow to operate but modern ΒΌ turn are almost instant and washing machines use an electric solenoid valve that is even faster, giving no time for pressure to even out.
    iron pipe should be no problem if it is OK just leave it alone as your plumber said. One possibility is to remove the head from the old tap and remove or fix any loose jumper in it if it is no longer required, but usually loose jumpers only cause trouble if the cause is downstream of them (after the cock) but in the wonderful world of plumbing you can take nothing for granted.o_O
     
  17. zenonithus

    zenonithus New Member

    Thanks teabreak that's really helpful. I did ask the plumber about removing the lose jumper inside the stopcock, though he thought that as it's around 100 years old it could either break the thread at the top by loosening it or there are no thread caps that size to replace it as it is so old. Though could a lose jumper in the stopcock make a sound that loud? It pretty much sounds like hitting the pipe with a hammer.

    I guess the cheapest hassle free option would be to offer to install an arrestor on downstairs washing machine. Would this only need to be connected to the cold? As it is the water main that is getting the banging. Their hot water is a separate system.
     
  18. teabreak

    teabreak Screwfix Select

    Just the cold assuming like most machines these days it is cold fill only, some older ones are hot and cold fill and if then connected to a combi boiler it might be an exception.:)
     
  19. zenonithus

    zenonithus New Member

    It's a new one so I'm assuming it is cold only. So with the jumper noise does it get really loud like banging the pipe with a hammer? Or is it a mild noise? I can't find any examples on youtube or anything
     
  20. teabreak

    teabreak Screwfix Select

    It can be anything from a light tapping to a really big thump.
    Sometimes if pipework is not supported the pipe can jump about.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice