Plumbing Nightmare - reposted

[bwhh1980]

Plumbing Nightmare

• Megaflo in attic (2012, serviced last 2015)
• Worcester boiler in kitchen (2012, serviced last 2015)

Jun-15: New washing machine installed, same cold feed pipe. There have been no changes to plumbing circuit for nearly 3 years at this stage.

Aug-15: First hear quiet bang/back and forth click after water used (hot/cold, up/downstairs). It seems to be coming from the attic and airing cupboard. Identified as cold mains pipe.

Sep-15: Plumber 1 is upgrading radiators and has a look at the noise. States that it is “100%” the toilet valves. One that seems faulty to him is replaced. No bang for 4 days.

Oct-15: Plumber 1 states that it must be the other valves too, so 3 more are replaced. At same time our ensuite basin tap fails and is replaced along with flow reducers to lessen noise. No bang for 3 days. When I finally get hold of Plumber 1 he rejects responsibility and states “it’s a problem with your system”.

Nov-15: Then he inspects the bang and states a faulty non-return valve on cold mains in attic is to blame. That or the header tank, but given that heating hadn’t been switched on since February, we proceed with the replacement valve. No bang for 5 days.

Dec-15: Plumber 2 returns to service boiler and megaflo (all fine), and investigates the noise and it suddenly stops when valve in attic for spare bedroom ensuite shower cold water is turned off. It makes sense as it was used a lot at the beginning of August. No bang for 8 days. Plumber 2 “too busy” to return. Turning the valve off stops the bang at the time, so when going to bed I have to do this every night.

Jan-15: Plumber 3 inspects and after speaking to South East Water and Megaflo (I’m told), they suggest installing 2 shock arrestors on cold mains in attic which we cautiously agree to have fitted. No bang for 2 days. As a test I have switched off the following valves at times but the problem persists (washing machine, spare ensuite shower hot & cold, main ensuite shower hot & cold).

We have spent nearly £1000 on fixing a problem that fully trained and well paid professionals can’t resolve, and of more concern don't persist with. We have been told what the solution is several times but without anyone preparing to guarantee their work, meaning we take a gamble each time and always end up losing. There simply must be a solution to this.

I appreciate all your comments as people who know more than myself on plumbing.

 

[bwhh1980]

PRV in attic but not at point where mains enters house.

 

[ShaunCorbs]

Does the noise still stop when you turn the stop tap off for the spare bedroom?

 

[bwhh1980]

Until the last set of works, the noise did stop when turning off the valve for the cold feed to the spare room shower, but would come back when the water was next used and the noise would more rapid. It was a way of stopping the noise so we could sleep, otherwise it would go on for a few minutes, gradually slowing down and fading.

However, it seems (last night) that the shock arrestors have stopped this method from working. When turning the valve to off the noise became more rapid and when turning back to on it was still there

 

[Best]

I would start with the basics. Firstly, because yours seems a puzzle, I would look at the mains stopcock and perhaps replace the tap washer inside it. They can cause a similar problem believe it or not. Also ensure the stopcock is full open.
Next I would check all the toilet fill valves and any other stopcocks on the mains.
Strange things happen. I have a friend who replaced her old washing machine and hammering then started through the hot pipes if a ceramic disc tap was turned off. I believe it had something to do with the old machine hose was absorbing the shock previously. But not sure.

 

[bwhh1980]

I've wound the stopcock open to full. All toilet valves were replaced.

 

[andyplumber2009]

Why would a problem occur after 2 months rather than almost immediately?
When you had the new washing machine:
- Was it a direct replacement in the same position?
- Did you keep the same hose?
- Was the previous machine fed off hot and cold supply as the new one will just be fed off cold?

And a question to the forum. If the new machine was hot and cold so now there is no plastic pipe on the end of the previous hot, combined with a couple of months of use maybe letting the machine move a little and "pinch" the pipes so no movement, could this cause it?
Is it worth pulling the machine out from its location for a day or two, run a couple of loads and see if any difference?

 

[tommy1712]

What's the incoming pressure?

 

[plumben]

The trouble with this sort of problem is it can be very hard to trace, sounds like plumber 1 has tried all the common things, but you can end up replacing all the valves in the system to find it, if it was me I would try fitting a shock arrestor on the incoming main, But this sort of problem can also be un clipped pipe work

 

[Ric2013]

Of course, whenever a plumber does any work on the house, what does s/he do first? Turn the stopcock off. Could an old, loose-jumpered stopcock * be causing grief?

EDIT * or other servicing/isolation valve

 

[bwhh1980]

- Yes same position, but to my knowledge we used the hose supplied
- Always cold supply

Machine has been moved out a couple of times for cleaning. When I hear the noise, I don't hear it where the machine is

Why would a problem occur after 2 months rather than almost immediately?
When you had the new washing machine:
- Was it a direct replacement in the same position?
- Did you keep the same hose?
- Was the previous machine fed off hot and cold supply as the new one will just be fed off cold?

And a question to the forum. If the new machine was hot and cold so now there is no plastic pipe on the end of the previous hot, combined with a couple of months of use maybe letting the machine move a little and "pinch" the pipes so no movement, could this cause it?
Is it worth pulling the machine out from its location for a day or two, run a couple of loads and see if any difference?

 

[bwhh1980]

I'm unsure on this.

What's the incoming pressure?

 

[bwhh1980]

Nearly all pipework is clipped where possible. But why would it start suddenly when no changes to pipework had happened for 3 years?

The trouble with this sort of problem is it can be very hard to trace, sounds like plumber 1 has tried all the common things, but you can end up replacing all the valves in the system to find it, if it was me I would try fitting a shock arrestor on the incoming main, But this sort of problem can also be un clipped pipe work

 

[bwhh1980]

If it were the stopcock, wouldn't the noise originate from it?

Of course, whenever a plumber does any work on the house, what does s/he do first? Turn the stopcock off. Could an old, loose-jumpered stopcock * be causing grief?

EDIT * or other servicing/isolation valve

 

[bwhh1980]

Thanks for all your comments. I'm hoping we can get to the bottom of this

 

[Best]

If it were the stopcock, wouldn't the noise originate from it?

No, not necessarily. Often the noise will sound from the opposite end of the plumbing from the source. I once had to reposition a washing machine and repipe from a kitchen and out to the far side of a garage. I used the original stopcock that solely supplied the machine in kitchen, but as working late I didn't relace the washer. A hammering noise could be heard in garage but customer was amazed when I replaced the kitchen stopcock washer and cured it

 

[tommy1712]

I'm unsure on this.

That would be the first thing I checked myself, 7bar of incoming is gunna make things bang! It would also explain the intermittents of it as athe pressure fluctuates with the demand