water pressure reducing valves and a water leak

[Stephen]

Hello,

I posted this under "mains water" but no-one has looked at it, so I'm reposting with a more descriptive title.

Our pipes keep making "kicking" noises when the (cold) taps are turned on. I saw that a PRV was cheaper to buy than a pressure gauge so I bought the Comap PRV from Screwfix. Has anyone used one of these? How do they work to reduce the pressure?

part 63442:

I fitted the supplied gauge but could not leave it in place permanently because it leaked. Do you have the same problem with yours or is mine faulty? I wonder why they don't supply a washer of some sort to stop this?

With the screw turned to allow maximum pressure, my supply appeared to be 4 (bars?). Turned down to the recommended 3 (bars?) the kicking noises have gone.

It came with some clever adaptors that allow 15mm pipe to fit inside

22mm connections, I presume by friction. Are these reliable?

I couldn't find them when I had a very quick look at Screwfix but they are like part 23608 at Toolstation:

Whilst on my hands and knees under the stairs where the water enters the house, I found that there is a slight leak. The water enters the house in a black plastic pipe. This pipe looks 22mm. It goes into what looks like a 22mm to 15mm straight adaptor from which runs 15mm copper to the stop c*ck. The 22 to 15mm compression fitting and the pipes were wet. Possibly the copper pipe was wet from condensation onto the cold pipe but I would not expect the plastic pipe to have condensation; I'm thinking that it is more likely that there is a leak.

There's not much of the plastic pipe to play with. What's the best solution: change the 22mm olive? Should I use one of those Fernox leak sealing pastes?

Thanks, Stephen.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Stephen saying something like:

It's a spring-driven thing. When you adjust the doodah, you actually load or unload the spring to the desired pressure.

It's often a taper thread on those, so a layer of PTFE tape will do it.

[Dave]

Is this happening on all of the cold taps in the house and are they mains pressure fed?

Dave

[Stephen]

I'm sure I've seen a cross-section that shows a spring but I still can't work out how a spring can reduce the water pressure.

Why didn't I think of that!?

Thanks.

[Stephen]

Hello. Yes, all cold taps (except bath) are mains fed and the pipes knock(ed) when any of these taps or the washing machine opens.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Stephen saying something like:

[John]

Washing machine hoses tend to be the cause of this problem - a shockwave causes them to expand slightly and then cause a sort of recoil. Do you have several in the house - if they are not really well reinforced then the problem can be worse.

[Stephen]

Only one washing machine but there is also a dishwasher, and I guess their hoses are the same? Perhaps I should have replaced these? Too late now but I know for next time. Thanks.