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.