New stopcock and pipe - any thoughts?

[Wonderbug81]

For reasons I won't bore you with, my neighbour's builder replaced my old metal stopcock and pipes with new plastic fittings without asking me. I'm now trying to make sure the work is OK or decide whether to get it done again.

He hasn't fitted to the wall - what is the best approach for this as I now have a water hammer issue as well!

He fitted the Plasson 3407 stopcock which seems to be WRAS approved. And he used a FloPlast MDPE pipe coil.

Any advice welcome as to the best approach on all of this as right now I have the time to get it right!

I’d be furious. Why would he do that?
I have a water hammer I can’t get rid of and it’s bloody annoying. I fear something is going to blow/leak every time I put the washing machine on. I’d be wanting that sorted at the very least. I don’t know anything about the parts you’ve listed to know if it’s better or worse that what you had before though.

Oh I am. I've made it clear if it happens again I'll take legal action. I had absolutely no noise before and now it's so bad it wakes me up in the morning.

All I know is I need to make sure it's WRAS approved which at least it is.

And apparently in the long run plastic pipes can be better than metal due to corrosion.

Meant to say, sorry you have to deal with it. I don't think it actually is that harmful when it happens, just sounds bad.

I haven't found plastic pipes prone to hammer, it is usually a metal pipe. You can deaden the vibration by clamping it firmly to the wall.

You probably have better flow with the new pipes. The static pressure will be the same, but the pressure under flow may well be higher (i.e. you can have two taps running at the same time, with more water coming out than before). It's possible that your old stopcock had been screwed down to restrict flow (people often do that to hide hammer) and the new one is fully open.

Water hammer is usually caused by a valve shutting abruptly. Some washing machines do that. A ballcock in a WC cistern or a cold water tank can do it. Ceramic taps (with a joystick instead of a head or capstan that screws up and down) can do it. It may occur when a valve is old and worn out.

Can you identify what causes the hammer? Is it one bang, or repeated knocking that slowly subsides?

BTW pipe clips are very cheap, but there is effort in drilling and plugging the wall to screw them in. In most cases plastic clips are fine, preferably with a fold-over top that snaps tightly into place. I would guess your new pipe is blue 20mm, and your old pipes copper 15mm, but that needs to be verified for a precise fit. I would start with the metal pipes because IME that will be where the noise is coming from.

I can help with the appliance that causes it if I know more.

If you want a nasty bodge you can tighten the stopcock.

Thank you so much! That makes sense. The hammer is a regular tap tap tap/knock knock knock when the boiler is on and more water runs through central heating. It sounds like it's running all the way up the house along one corner (I assume it's all the same metal pipe).

It could also be my 3 year old washing machine (rumbles a lot during cycles, possibly some movement).

As it coincided with when the stopcock was replaced I assumed it was the movement from the stopcock pipes rather than anything else but I'll try reducing the flow as well as getting them to fix everything down.

Tapping when the boiler is running might be pipes expanding with the heat and rubbing against joists. This happens when they are heating up, then stops when the temperature is stable, and starts again when it is going cold and contracts.

A washing machine is usually a single bang when it closes the valve at the end of each fill.

Long banging that may get faster and then stop is probably a ball cock in a WC cistern or a cold water tank.

Thank you. What I don't understand is why there was never a single noise before the stopcock was changed. Same pipe running up the corner wall as before.

It's a very regular concurrent tap so maybe more likely to be the WC.

Maybe I need to get a plumber here if the neighbour's plumber doesn't resolve it.