Noise from pressure reducing valve

[andymay]

Hi, I wonder if anyone can help.

My parents have a PRV fitted to the incoming mains in their kitchen, which for months has made an intermittent whirring noise which is driving them crazy.

Today I have worked out that the noise happens when the ballcock in cold water tank in the loft is closing. When the noise occurs, if I lift the ballcock, it stops.

So I'm left wondering what might stop the noise. The PRV makes a very quiet noise whenever there is a flow; could it be that a resonance in the pipe feeding the cold water tank makes this noise louder? And if so, might an expansion vessel put somewhere along this pipe stop the problem? Or does anyone have any other suggestions?

Many thanks,
Andy

 

[ChrisR]

Can you find a pic of something similar?
Some types have a non-return valve in them which oscillates at small flows. DOes the WC come off the low pressure side?
A pair of pliers.... and of course a replacement NRV in the pipe.

Perhaps more likely is the ball valve itself, they do it a lot and the pipes carry the noise - try changing the washer.

 

[andymay]

Thanks Chris
I've found the brochure for the valve - its http://www.caleffi.com/en_IT/Technical_brochures/01024/01024.pdf

I don't think it has a non-return valve. Everthing else in the house is also on the low pressure side, but does seem to be the water tank filling that causes the noise. But I can't hear the noise at all from the ball valve itself - it definately seems to be the PRV's own noise getting louder.

 

[jay1]

have you got a strainer fitted before the prv, may be some debris stuck in prv.take it off and clean and see if it works

 

[haga]

I have to say I've used loads of Callefi PLV's and never had a noisy one, I've had dozens of noisy non-return valves tho, if it only makes a noise on slow water running fit a Torbeck (or similar) valve instead of the ball valve in the tank, that'll cure it
haga

 

[Goodmedalist]

My PRV was making loud creaking and drumming noises so much that I couldn't sleep. It turned out that debris built up in the valve. I took Jay1's advice but instead I replaced the entire valve. I used a different brand, Kwikot. The valve is now dead quite, even after using hot water, no noise. A PRV usually consists of 2 main parts: valve (brass) and cartridge (plastic). Replacing the cartridge did not silence the valve, the main brass part of the valve was the problem. I hope this helps someone not to waste money on replacing only the cartridge, and ask the plumber to clean or replace the brass part of the valve.

 

[Agile]

I fail to imagine how the brass body can change to become faulty!

As suggested I would be inclined to dismantle and clean it.

If that did not solve the problem I would add a shock arrester or an "inductance" close to the ball valve and see the effect of that.

I would probably put an iso valve on the line to the shock arrester so that I could alter the "Q" of the circuit.

Tony

 

[HERTS P&D]

Tony - this post is 4 years old!

Andy

 

[Goodmedalist]

I fail to imagine how the brass body can change to become faulty!

The brass body can be "faulty". Pipes can corrode, this corrotion debris and other dirt can flow in the pipes and lodge in the brass part of the valve, which has a moving part inside. This is perfectly normal especially in older residences. The brass wont be damaged, but dirt, rust, corrosion debris, can build up over time. This is exactly my case. I looked inside the old valve and I was shocked. Looked like thick layer of 'rust' buildup. No way that valve could have worked properly.

 

[Agile]

I dont consider something to be "faulty" just because there is some dirt in it which can be cleaned out.

If you took that view then copper pipes used for central heating would then be classed as faulty!

 

[Goodmedalist]

I dont consider something to be "faulty" just because there is some dirt in it which can be cleaned out.

If you took that view then copper pipes used for central heating would then be classed as faulty!

True. My valve was not faulty, but dirty inside. Cleaning it would have worked too.