pressure reducing valve fitted but still got water hammer

[steved54]

Please can someone help . I have fitted a pressure reducing valve and changed the stop tap due to water hammer but neither have worked , all the pipes are secure ..even at 1 bar it is still banging .The tap has to be left running when the washing machine is on otherwise it is banging all the time. It does not bang with the toilet .I have isolated the shower and turned this off as this was worse but I am now stuck and don't know what to do . We had a plumber in he fitted an air chamber (think that's what its called ) this also has not not worked , so I have taken this out and fitted the pressure reducing valve ..Has anyone any idea what else can be done .

 

[Space cat]

You could try a dead leg. That's probably not the right word but what I've got is a short length (about 300mm) of pipe with a stop end on it. This branches upwards from the pipe leading to the washing machine then turns immediately to run horizontal again. It traps a long, thin air bubble and acts as a spring and damper.

 

[xr4x4]

Yes they are are called dead legs and can cause water hammer.

 

[spraggo]

The rubber hose, usually supplied with the W/M will normally stop water hammer from the machine. Is this fitted?.

 

[Charnwood]

Why not fit the correct thing for the job – a hammer arrester. 3/4" male to 3/4" female – fits between the machine and hose or between the valve and hose.

 

[steved54]

Its not just the washing machine that's causing the trouble it's all the taps in the bungalow . We have isolated washing machine , dishwasher bath taps and the shower and it still bangs there are no isolating valves on the kitchen sink and sink in the bathroom so these have not been isolated .

 

[HERTS P&D]

Is the main stop cock fitted the right way round?

Andy

 

[Phill Peck]

Why did you fit a pressure reducing valve?

The problem will be with a cartridge or washer in one of your taps or ball valves regardless if the pressure is 1 bar or 5 bar

Or possibly a new fill valve in washing machine but this is rare because of hose as already said

 

[steved54]

Yes the stop tap is fitted the right way , we fitted the pressure reducing value because the plumbers merchant sequestered it . would one faulty tap cartridge cause water hammer to all the house ?

 

[Phill Peck]

Yes operate each tap/ballvalve individually to identify the culprit and then replace

 

[snb]

is your system pressurised or gravity?

If it's pressurised and it's happening on everything apart from the toilet then i would look at replacing the mains stop cock.

If it's gravity for some pipework then tie up the ball valves in the loft cisterns and see if this stops it.

 

[steved54]

Replaced stop cock again and it is now worse . tried getting rid of air in pipes still no look , telephoned plumber he says done everything he would have done . Pressure set now at 2bar and now vibration is also when taps turned on and off . would we have fit a hammer arrester. to all fittings or just one by the stop cock. I am at my wits end no plumber wants to know .

 

[inmcdonalds]

Was wondering if you ever worked out the problem? We have this too as it's continuous ie unrelated to taps or ball valves switching off. I'm convinced it is something in the water board network.

 

[Madrab]

If you are getting water hammer when all the outlets are closed i.e. no water is moving anywhere in your house, that's all the taps, toilet, boiler, cold water cistern, appliances etc, then it could be an external issue. The pressure wave is entering from the outside pipework to yours. Easiest way to test is to shut off all your outlets at their isolation valves and see if it still occurs.
Unless you can guarantee that no water is moving in your pipework then it would be hard to go to your supplier and ask them to investigate on their end I would think.

 

[dcawkwell]

Fit an expansion vessel set to approx 2.5 bar on cold main pipework after the stop valve.
Sorted.