tapping and knocking pipes and irregular mains water flow

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Hi all. Sorry for the long post here but im trying to put in all the details that could help.

im hoping someone can help me with an issue thats driving me mad.

About 6 months ago i had to change the flexi hose supply to the downstairs cistern. After i put the water back on i think i might have made the pressure a bit high. Anyway after a week or so i started hearing knocking pipes from behind the wall where the pipes travel from downstairs to up (my kitchen and boiler are upstairs). i also had what sounded like water hammer every time a tap was closed. i lowered the pressure a bit but the knocking continued, it was intermittant and seem to follow no obvious reasoning (i.e they would knoeck even when during summer when boiler wasnt running, no taps or toilet had been used etc).

Things seemed to get worse a few weeks ago when i distinct, loud tapping noise would come from the channel where the pipes run (it is tiled over so cant get into it) this tapping was completely different to the earlier knocking, my first thought was that it sounded like a leak where the water sripping onto a copper pipe, i cannot find any water tho so hopefully this is not the case. The thing is, when i turn on a tap (either hot or cold) the tapping stops until i close the tap again. however when the tap is open it is not a constant flow that comes out of it, it constantly switches from heavy to light to heavy etc. This only happens at the times when the tapping noise is happening, the flow is fine at other times. my 1st thought was this could be air in the system but the cold water is fed direct from the mains, i dont know much about plumbing but i thought air in the mains was only caused when the supply had been cut off and is generally cleared quickly.

Does anyone have any ideas as to what could cause this, i know its a bit vague and could probably be a million things but i am getting myself a bit worked up worrying that there could be a leak or some sort of ipending disaster!

Any help at all would be very much appreciated.

Thanks
 
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First thing that comes to mind is pipes out of sight are not clipped and the water pressure is making the mains pipe whip, also I dont know how high the water pressure is in your area but may be worth turning in down lower if you have high pressure mains.
 
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Anybody else have any ideas about what could be causing this? i think i am going to phone a plumber ut next week, my worry is it wont be happening when hes out so there wont be much he can do.
It is certainly happening alot more frequently, it has went from happening every few weeks to every day (today it has happened twice). I think there may be link between either flushing the toilet or running the hot water and this happening. Once it stops i am going to try these seperaty to see if any of them cause it to start again.
 
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My wife just did dishes there and the noise has started again. Seems to be linked to using the hot water. Strange thing is whenever running the cold tap the tapping stops until the tap is closed again.
 
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Clutching at straws, but I have known tapping and rapid knocking noises caused by the washer inside the stoptap in house breaking up. This leaves the brass jumper to oscillate as the water passes over it.

If you turn your stoptap off fully and a tap still dribbles, this may be a sign. Maybe worth ruling this out, but as you have operated the stoptap recently, it could have caused the problem.
 
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Thanks for the reply

I have noticed previously that when i turn the water off the valve does not fully close and a certain ammount of water continues to flow (this is not just water already in the system, even with all taps open and water off a small amount of water will flow continuosly)

The knocking pipes did start not long after i had the water off but that was around 6 months ago, this tapping noise has only started in the last month and is quite distinct to the knocking, also the tapping happens when no taps etc are open so i assume that would suggest there would be no water flowing through the stop valve and therefore nothing to oscillate the brass?
 
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, also the tapping happens when no taps etc are open so i assume that would suggest there would be no water flowing through the stop valve and therefore nothing to oscillate the brass?

Yes, the tapping would only happen whilst water was flowing. Sounds like your stop tap needs a new washer anyway.
 
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http://www.youtube.com/watch?v=1g89A77_ONY

Hi all

My issue with the pipes seems to be getting worse by the day, tried to get a few plumbers today since im off work but couldnt get any that were available.

Ive attached a video i took, if you turn your speakers up you should hear the banging and then notice it stops when i turn the tap on.

The strange thing is it has been happening randomly, when heating is off, no water been run recently etc, i also spoke to my next door neighbour this morning and he says hes been hearing banging from his pipes. Its strange, it is driving me mad tho
 
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Do you have gravity hot water or is it a combi?
If gravity check the CWSC ball valve that feeds the hot water cylinder when they go faulty and you draw hot water the mains cold replenishing the tank can sometimes create small ripples on the surface of the water making the ball valve bounce slightly on the surface which opens and closes the valve slightly sending shock waves through the pipework making them knock.
If then a cold tap is opened the water pulsates for a while until the ripples have settled.
If the washer is worn then flushing a toilet or turning a washing machine on can also create the same noise.
 
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Thanks for the reply.
I have a combi boiler system for my hot water. Also the tapping noise stops whenever either the hot or colt taps are run.
 
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Sorry to drag up this old topic but the banging issue has become much worse.
I put the issue onto the rated people website n a guy phoned up n said he thinks the problem is a damaged valve in 1 of the taps n a build up of pressure is causing the issue. He basically quoted me 250 quid to replace valves on my 3 taps however he hasn't actually looked at the job so I'm not sure about commiting to this.

My question to anyone knows about this stuff is does that explanation sound plausible? My worry is that it happens thru the night when no taps have been run for hours so I'm not sure how a tap valve would cause this, but then again when I open any tap the banging stops so it could be something to do with pressure build up.
If any1 has any thoughts I'd very much appreciate them, I'm at a stage where I hate being in my house due to this issue so I'm desperately wanting it fixed.

Thanks
 
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