Water hammer or air lock?

[richie51]

I moved into a detached bungalow last June, and last Sept I had a problem with clanging pipes which I only heard in the early hours. This stopped in May for 4 months but returned as soon as it got colder a month ago. I've been woken by loud banging in pipes about 5 to 5.30am. A local plumber suggested I try turning the main stopcock off, which is outside in front of my house, then emptying all water from every tap. Then turning off the sureswitch inside. Leave it like this overnight. He wanted to see if it was an air lock or he seemed to think it could be hammer. It did make a difference. I got woken by very faint noises which were only a fraction of what the noises had been. The noises started earlier than before too, about 4am. It seemed to stay this way for about 3 days then the noises gradually got louder again. I'm not sure if an air lock or hammer will build up again if there is any in pipes. That's if this is the problem.I did read on a plumbing website that I may need to try this procedure again if the problem has been there a long time. I repeated the same procedure Friday of emptying all water from taps (in the daytime though,which I left to settle for about 5 hours,not overnight) which made things worse! I got woken Saturday morning by a loud knock every 15 mins or so starting at 3.15am! There was one final very loud clang at 5.15am. Sunday morning I got woken by one clang at 3.30am and heard nothing more. I have affected the pattern of noise with my doing this procedure twice. Severn Trent are coming here Tues to investigate,though I'm not sure what they could do. Would you suggest I do this procedure every day (overnight) to see if this clears anything up for good. Maybe doing this procedure several times on consecutive days will finally flush out any hammer or air. Could this stop hammer or air lock having a chance to build up again? Thanks.

 

[chris watkins]

What hot water & heating systems have got installed?
If you have isolated the incoming mains over night & it is still happening it can't be mains related, i.e. water hammer or air lock.

 

[richie51]

Thanks for the reply. I've got a conventional heating system (hot and cold water tank), and central heating. I only isolated the incoming mains for one the one night (last Sunday) and I heard a couple of very faint noises, but the banging in pipes that I had heard didn't happen that night. I left things as normal and for the next few nights I heard only a few faint sounds, but this gradually got louder later in the week. I did isolate the system a second time after emptying all taps on Friday morning til lunchtime, but I didn't leave mains isolated overnight. I heard loud noises the following morning at 3.15am, but just one clang last night. My doing this has affected the pattern of noise if nothing else. It did stop for 4 months during the summer and returned a month ago, almost as if the cold triggered the problem to restart. My isolating the mains overnight once, did improve things temporarily. Someone advised me to leave cold kitchen tap on lowest trickle overnight, and I heard nothing that night. If you don't think it's hammer or an air lock, what do you think it could be? Could it be an unclipped pipe?

 

[chris watkins]

Poltergeist ?
No it is most likely to do with pressure surges in the mains system at those sorts of times speak to water undertaker to see if they can monitor it.
You might wish to consider installing vessel which will act as a shock arrester (like a shock absorber on a car).
It won't be air in the mains system but could be from poorly clipped pipework.

 

[richie51]

Thanks Chris. It sounds loudest in main bedroom, though I know sound echoes to another place, so could be anywhere. The plumber did suggest shock absorber. Where would be best place to instal this? If it turns out to be unclipped pipe, would an absorber still stop the pipe clanging? I have thought it might be an unclipped pipe, but why did noises stop for 4 months during summer?Thanks.

 

[Deleted member 32524]

Fit a pressure reducing valve just after main stopcock. This will keep house at a constant pressure.

 

[richie51]

Thanks Duncan, do you mean stopcock inside house? I have a sureswitch in airing cupboard, which I know some plumbers don't like. It's a new one though, installed last Oct. The plumber who called here last week (he's not the one who fitted it) said they are good, he uses them all the time. The other stopcock is outside under a metal lid in front of property. If it turns out one of the pipes is unclipped, will this valve still stop banging in pipes in early hours? Thanks.

 

[Deleted member 32524]

Hi Richie. Yes after the stopcock in the house.

 

[AMGasServices]

I think it may be a shared water supply and once’s one of the neighbors uses a the cold water you get the noise.

 

[dancinplumba]

Fit a pressure reducing valve just after main stopcock. This will keep house at a constant pressure.

Needs an expansion vessel too

 

[richie51]

I've just heard a loud clang which sounds like a pipe knocking against a wall or something. This is about an hour after I've turned central heating on. If it is an unclipped pipe, I guess the only solution is to get the floor up til pipe is located. This will be a problem as I have chipboard flooring instead of floorboards. I've heard about a gadget that can locate pipes.Is it called a stud detector? Are they expensive? Would it best for me to invest in one so I can give it to the plumber so he can locate pipes with minimum damage. I wonder why I didn't hear anything from May til Sept? I wasn't even putting the heating on in Sept when the noise returned. Any other suggestions would be greatly appreciated. Many thanks.

 

[richie51]

I think it may be a shared water supply and once’s one of the neighbors uses a the cold water you get the noise.

Thanks. I did think I may be shared mains,but I am detached and I have my own external stopcock. Severn Trent are coming here Tues to investigate, so I'll ask them about this.

 

[Deleted member 118554]

Thanks. I did think I may be shared mains,but I am detached and I have my own external stopcock. Severn Trent are coming here Tues to investigate, so I'll ask them about this.

Your problem sounds just like mine - how did you get on may I ask, did you find out what the problem was and what you did to rectify it ?