The hot water supply in our bathroom goes under the bath towards the taps. Just before the bath tap (not a mixer) it splits and feeds to a mixer shower head.

When the hot tap on the bath is opened, there is an almighty repetitive banging in the pipe. Nothing at all when the shower is switched on.

So is that a knackered tap or water hammer.

I’d have thought that is the latter, it would do it with the shower being on as the flow is still the same, maybe, perhaps?

Advice and help greatly appreciated.

Thanks

Is the pipework secured properly?

I dont know to be honest. It reverberates around the house and part of the run has been installed behind a new false ceiling as part of a kitchen renovation. It makes a ruddy awful din.

You can fix a water hammer by turning all the taps on or something (google it).

If that don’t fix it, it will be something else 😛

Sounds like water hammer, usually caused by too much pressure in the system. Opening all the taps will cure it short term but you need to reduce the pressure otherwise it will only come back.

Why is it only the bath tap. Kitchen tap is ok as is the loft bathroom tap?

By reducing the pressure, presumably the tap in the pipe to the boiler can be closed off without affecting flow, unlike the stop tap. I think that might be a pressure control tap.

Admittedly, I am lacking on detail and knowledge here!!

Do you have a cold water cistern feeding a hot water cylinder? Have a look at the float valve while the water is hammering, if you see it vibrating then change it

Is the bath tap a lever tap and the rest traditional screw down taps?

If so, it’s the speed at which you can open/close the tap that causes it – the other taps are a more gentle on/off action.

Either way, a small expansion vessel called a shock arrest or can sometimes help. We had. A whole sheltered housing development retro fitted with them and the banging pipes stopped overnight.

It’s a mains fed combi hot water system.
The tap is a quarter turn lever tap.

If this helps.

What timba said. Had same problem last year and float it was.

A shock arrrestor sounds like it should do it. You’ll need to tee it into the pipe somewhere. It basically a mini expansion vessel about the size of tennis ball that does what is says on the tin.