Help please its driving me mad!

[Darren]

I have been trawling through posts for the last few months so before I go ahead and spend money just thought I would ask.
I know this has come up many times, as I have read most posts but I can't seem to find an answer as to why all of a sudden?
For the last few months but never before, (I have lived here for 14yrs) when any of my 3 toilet cysterns finish filling or my washing machine or dishwasher finshes filling or when I connect my pressure washer to my outside tap there is one bang from what appears to be the pipes as the water shuts off, always in the same place and always only one loud bang. I cant get to or see exactly where the noise is coming as it is under the bathroom somewhere or thats where it appears to be. My confusion is why or what may have caused this to start. No work has been carried out on the plumbing in the house over the last 12mths, the only thing I did have was a leaking gland on the stopcock at the begining of the year which I tightened up. Is it possible this is the cluprit as I have read about people suggesting these can be the cause otherwise it looks like Im going to have to go ahead and fit arrestors to all 6 areas?
Any help much appreciated.

 

[Plumbstar Tom]

may be that the water supplier fixed a leak and subsequently you have higher pressure.

if you run a cold tap and then flush the toilet keeping the tap running, when the toilet stops filling does it still bang?

 

[Darren]

Hi just tired that and it didn't bang, I will try all the toilets etc again tomorrow when the house is a bit quieter ( no kids or wife around) but it didn't appear to bang so is a prv the answer then fitted just after the stopcock.
Thanks for the reply.

 

[Plumbstar Tom]

yes, that would be the quickest and easiest solution

Sounds like there is an unclipped pipe under the floor boards so the sudden stoppage of flow is causing pressure wave and moving any unfixed pipe work

 

[Darren]

Hi Tom, I'll get one and fit it this weekend, will one of these suffice or do I need to be spending more money?
Honeywell D04FS-ZC 15 pressure reducing valve 15mm (1 pack)
I'm guessing once fitted its trial and error slowly reduce the pressure until the pipe stops banging, without loosing the flow through showers etc. I have a mains pressure hot water system, coil passes through tank which holds hot water for my heating system.

Cheers.

 

[Plumbstar Tom]

Looks fine, set it to 3.0 bar and trial form there

 

[Sparkgap]

Water hammer. Happens when valves in washing machines or ballvalves shut suddenly and the moving water (which has momentum) suddenly has to stop. Usual way is to put an air cushion by making a tee with 15 or 22mm pipe, vertical piece of pipe for 4" or so with end sealed. The air absorbs the pressure stopping the hammer.

 

[plumben]

Water hammer. Happens when valves in washing machines or ballvalves shut suddenly and the moving water (which has momentum) suddenly has to stop. Usual way is to put an air cushion by making a tee with 15 or 22mm pipe, vertical piece of pipe for 4" or so with end sealed. The air absorbs the pressure stopping the hammer.

Why not just fit a shock arrestor

 

[plumben]

Water hammer. Happens when valves in washing machines or ballvalves shut suddenly and the moving water (which has momentum) suddenly has to stop. Usual way is to put an air cushion by making a tee with 15 or 22mm pipe, vertical piece of pipe for 4" or so with end sealed. The air absorbs the pressure stopping the hammer.

Why not just fit a shock arrestor instead of contravening the water regulations and creating a dead leg of pipe work over the acceptable amount...

 

[Unregistered]

Hi so are you saying I don't need a prv as its not going to solve the problem what I actually need is shock arrestors fitted to every appliance and toilet that causes the bang?

 

[plumben]

Hi so are you saying I don't need a prv as its not going to solve the problem what I actually need is shock arrestors fitted to every appliance and toilet that causes the bang?

Usually its one outlet causing the problem not all of them, sometimes it can be a ball valve that the washer is going on

 

[wiggers]

Myself mate I would start at the stopcock put a new one on there about £7 this is highly likely the culprit. My company own 18000 houses and worked on thousands of them have never fitted a shock arrest or yet!
Failing that wc fill valve or ball valve in CWSC in loft ?
Give these a try I'm sure it will resolve the issue
Good luck

 

[JACKY]

I went to a customer a while back that had the exact problem, he was a bit of a diy expert and had clipped the washing machine hose under the sink unit, i pulled the hose out of the clips and the banging noise stopped instantly. Always make sure your WMhoses have plenty of space for movement.

 

[Darren]

Myself mate I would start at the stopcock put a new one on there about £7 this is highly likely the culprit. My company own 18000 houses and worked on thousands of them have never fitted a shock arrest or yet!
Failing that wc fill valve or ball valve in CWSC in loft ?
Give these a try I'm sure it will resolve the issue
Good luck

Thanks for the advice, I'm waiting for the PRV to arrive but in the meantime I'll change the stopcock, can you explain how this could be the cause, it's not leaking or seized.

Cheers.

 

[Darren]

Quick update whilst house is quiet and no water being used, I've isolated washer at ball valve and dishwasher at ball valve flushed offending toilets and I still get 1 bang as they finish filling. I've opened these ball valves back up and turned my stopcock down to where I have just enough flow to use showers and fill cisterns back up in reasonable time and the bang has gone? I'm thinking it's not advisable to leave this stopcock nearly closed so is it still pointing to a faulty stopcock that needs changing or is it a PRV I need after all? Sorry for all the questions, I will replace what ever needs to be replaced but no point in spending a fortune if there is one fix.
Thanks,
Darren.

 

[plumben]

New stop tap is where I would start

 

[Darren]

New stop tap is where I would start

Cheers that's what I'll do.

 

[Darren]

New stop tap fitted all lines drained and filled back up.... Still got the bang?

 

[Darren]

New stop tap fitted all lines drained and filled back up.... Still got the bang?

Fitted new stop tap but still have this one clunk when each toilet stops filling the cistern, washing machine, dishwasher and pressure washer shut off. If I close the stop tap a little it stops but toilets take a while to fill and if anyone turns a tap on showers and taps upstairs turn to a dribble.

 

[Tonycane]

Any sudden stop in flow will resonate through a faulty valve. I would be ruling out each toilet fill valve one by one, do you have isolators fitted at each toilet? If so turn them all off and try to replicate the clunk. Do you have a combi or gravity hot water system?

 

[Darren]

Any sudden stop in flow will resonate through a faulty valve. I would be ruling out each toilet fill valve one by one, do you have isolators fitted at each toilet? If so turn them all off and try to replicate the clunk. Do you have a combi or gravity hot water system?

Hi yes I have isolators at each toilet and washing machine, dishwasher and outside tap, noise is always in same place somewhere under floor or in wall. If I open a tap a little at the same time as flushing no noise? I have a ho****er tank that is my thermal store for heating, my hot water is mains pressure heated via coil as it passes through thermal store.

 

[Tonycane]

Turn all thE isolators off and run the cold tap on your sink, does it still happen when you turn the tap off? If not you have a faulty valve in a cistern, open one at a time and repeat running the cold tap.

 

[Darren]

Turn all thE isolators off and run the cold tap on your sink, does it still happen when you turn the tap off? If not you have a faulty valve in a cistern, open one at a time and repeat running the cold tap.

Hi I'll give that ago, it will be tomorrow now as I'm on nights but I'll report back thanks.

 

[Darren]

Turn all thE isolators off and run the cold tap on your sink, does it still happen when you turn the tap off? If not you have a faulty valve in a cistern, open one at a time and repeat running the cold tap.

I've opened my stop tap fully and before isolating toilets checked cold tap full on to off no bang, so I'm thinking that rules out faulty cistern valves? If I run a tap and flush the toilet there is no bang? Shutting my stop tap helps and does get rid of the bang but the toilets take an age to fill and the water pressure is then useless.

 

[Rickster123]

Have you had a shock arrester fitted as suggested earlier?

 

[Darren]

Have you had a shock arrester fitted as suggested earlier?

Hi no not yet, I decide to go with the cheapest option first, new stop tap but that hasn't cured it.The problem has only recently started so not sure why all of a sudden I would need shock arrestor as I have lived here 14 yrs without any issues but if that's the solution then I'll fit them. The only thing is I have 3 toilets, washing machine and dishwasher that all cause this bang so that's about £200 just for the arrestors before fitting, so I was hoping there maybe another solution.

 

[Darren]

Update I've just tried different taps in the house hot and cold and if you slam them off quickly I get the clunk this is the same with all isolaters closed or open?

 

[Masood]

The problem has only recently started so not sure why all of a sudden I would need shock arrestor as I have lived here 14 yrs without any issues.

As already said earlier up the thread, the water carrier may have upgraded the mains, fixed a leak or done other work that has improved your pressure.

 

[Darren]

As already said earlier up the thread, the water carrier may have upgraded the mains, fixed a leak or done other work that has improved your pressure.

Thanks so are you suggesting a pressure reducing valve is the answer or will that just be the same as closing my stop tap to get rid of the bang as that doesn't give me enough supply to make the shower usable.

 

[Rickster123]

Shock arrester

 

[Masood]

Thanks so are you suggesting a pressure reducing valve is the answer or will that just be the same as closing my stop tap to get rid of the bang as that doesn't give me enough supply to make the shower usable.

Shutting the stopcock will have no effect on the pressure. It will only affect flow rate.

 

[Darren]

Shutting the stopcock will have no effect on the pressure. It will only affect flow rate.

Yes that makes sense thanks, so is prv what your suggesting?

Shock arrestors have been suggested but as I uderstand it I will need to fit to all offending toilets etc, is that correct or can one be fitted somewhere.

 

[Masood]

Yes that makes sense thanks, so is prv what your suggesting?

Shock arrestors have been suggested but as I uderstand it I will need to fit to all offending toilets etc, is that correct or can one be fitted somewhere.

If you want a single whole-house solution, try a PRV.

In theory you could fit a single shock arrestor near the banging pipe, but if you can locate and access the pipe to fit an arrestor, you may as well clip it properly and not need an arrestor.

Or - you could methodically isolate and test to find which appliance/tap is wearing out and causing the hammer in the first place.

 

[Darren]

Thanks I will give the latter ago first tomorrow and if that fails try prv as one arrestor isn't an option as I can't access the pipe work making the noise.

 

[Ric2013]

I'm a newb. Don't shoot me.

Would a single shock arrester after the stopcock work? On the grounds that it would give the water somewhere to expand to.

 

[Darren]

Looks fine, set it to 3.0 bar and trial form there

I've gone ahead and fitted the prv, my water pressure was showing 2.5bar once fitted and I've slowly wound it in to 2-2.2bar and bang has gone at last and I still appear to have plenty of flow and pressure at my showers etc. I've only just fitted it so time will tell if all stays good. I have no idea what the pressure has been in the past but maybe it has increased of late by a repair externally as suggested.

Thanks for the help guys and I'll update in a few weeks to let you know if all is still good!

Cheers.

 

[Darren]

Didn't last later that day the bang was back! Not sure if the PRV is faulty though. Set at 2bar with stopcock fully open and taps etc closed, same evening it was reading 3.5bar and the next morning it was reading 1.5bar and no flow at the shower. Set again at 2bar and it was varying between 2.5-1.8bar through out the day. Tonight it was reading 3bar and now is back to 2bar, have I done something wrong or is it faulty?

 

[Alex Knight]

Have you put it on backwards lol

 

[Darren]

Have you put it on backwards lol

Unfortunately no, I wish that's all it was but I did double check.

 

[PlumbBobBob]

no all that is happening is that at different times of the day there is differing demand on the mains i.e. over night there will be less demand so pressure rises and during the day there is more demand so pressure will be lower.

 

[Rickster123]

Shock arrestor... Still...

 

[Darren]

no all that is happening is that at different times of the day there is differing demand on the mains i.e. over night there will be less demand so pressure rises and during the day there is more demand so pressure will be lower.

Ok but on the evening 8pm it was reading 3.5bar nothing using water and in the morning 5am it was 1.5bar nothing using water and as the gauge is after reducing valve I thought it should always show the set pressure not fluctuating supply?

 

[AWheating]

you need to take the reading on the gauge while you have a tap running and set it as a working pressure.

it sounds like the main has a fluctuating pressure and has probably had an increase in pressure from work or being turned up by the supplier which is not uncommon when demands increase and decrease. this is more common in industrial areas.

 

[Darren]

you need to take the reading on the gauge while you have a tap running and set it as a working pressure.

it sounds like the main has a fluctuating pressure and has probably had an increase in pressure from work or being turned up by the supplier which is not uncommon when demands increase and decrease. this is more common in industrial areas.

I'll give that a go.
I still don't understand how if I set the pressure on the gauge which is on the outlet side of the valve at 2bar any fluctuation on the inlet pressure, increases the gauge reading as it has to pass through the PRV which is set to 2bar. This would suggest it's not working or am I get things confused?

 

[Darren]

I'll give that a go.
I still don't understand how if I set the pressure on the gauge which is on the outlet side of the valve at 2bar any fluctuation on the inlet pressure, increases the gauge reading as it has to pass through the PRV which is set to 2bar. This would suggest it's not working or am I get things confused?

I'm still a little confused regarding the above or if the PRV is working as should but after playing around only one toilet was causing the bang. I've fitted a fluid master 400 flush valve to that cistern and hey presto bang has gone on that toilet too, so I opened the PRV up fully and my other toilet began to cause a bang after flushing so I changed the rubber washer, still the same so I have replaced the 10yr old fluid master 400 in that cistern with a new one and it has now stopped causing a bang as the water shuts off.
My water pressure visually does seem higher than it used to be but the gauge only shows a max of 3-4 bar is this high or not? If the PRV is working correctly I'll keep it, incedentally I fitted it in the vertical position as the instructions said this could be done and ther was minimal work involved fitting it in that position, could that be a reason why I'm getting varying reading on the gauge? As I said before I was under the impression if I set it to a reading of 2bar on the gauge it wouldn't matter what the supply pressure was as the gauge is after the valve which should be controlling it at the set 2bar.

 

[Tonycane]

Probably had a water main upgrade somwhere along your line highlighting a tired valve, that's why I always check tie cisterns first