Concealed shower banging

[Matt887]

I have a concealed shower that is banging when on both the big shower head and the small shower head in the riser any ideas? Divertor valve?

 

[Wayners]

Too much pressure? I fitted a pressure reducing valve to our shower as per instructions.
You can also look at water hammer arrester.
Difficult to say what will sort it

 

[dilalio]

Is it high or low pressure?
Do you have a combi boiler?
Cylinder?
Pump?

Possibly the built-in NRV in the shower valve, if it has one.

What brand/model shower?

 

[Matt887]

Its high pressure of a unvented cylinder. So should be of balanced cold so both supplies to it 3bar.

 

[dilalio]

Its high pressure of a unvented cylinder. So should be of balanced cold so both supplies to it 3bar.

Is it balanced though?
Photo of combi valve?

 

[Matt887]

Is it balanced though?
Photo of combi valve?

Id have to check that. Could unbalanced supplys case it?

 

[Matt887]

Obviously dont want to strip the shower down if it's a external problem

 

[dilalio]

Id have to check that. Could unbalanced supplys case it?

Yes, potentially. If cold supply higher pressure than hot, it can push back at the shower valve, against the hot NRV, causing it to pulse and reverberate through the pipework.

However,
is it just the shower doing this?
Is it all the time?
Or just this is the first draw point in the mornings?
Is it during use or when turned on/off?

If during use, then more likely the thermostatic cartridge I'd have thought - as it tries to adjust temp to set point.

I have one at the moment, first draw off in the morning, causes machine gun noise.

It's coming from the EV and combi valve. Happened since I recharged the EV which was full of water. I could hear the bladder popping off the sides of the vessel as I regenerated it.
Since then, they've had a racket every time cylinder reheats and they then draw HW!
I can't tell if it's EV or combi valve so I'm going to replace both.
And the TPRV, as that's also dripping through tundish.

 

[Matt887]

Thanks for the response. So it's a concealed shower 3 way divertor. So on/off valve. Temperature valve. And valve that diverts from shower head to shower riser arm. It bangs when the knob is moved to divert the water from the shower head to the shower riser arm. Any ideas?

 

[dilalio]

Faulty divertor within the shower.

 

[Matt887]

So it's a case of seeing if can identify the shower and get a new divertor for it?

 

[dilalio]

So it's a case of seeing if can identify the shower and get a new divertor for it?

I'd say so and also check if pressure/flow is within the valves limits.

Might even be worth taking the current one out and see if it's got any obstructions in it, or try and clean and lubricate it. Worth a look.