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.

 

[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