Pipe banging

SMG · 2 Jun 2013

I fitted a Prestex P404 TRV under my wet-room sink. Water pressure is a steady 3 bar, balanced hot / cold feed. Before, there was no noise, no hammer, now, whenever I turn the tap off, I get pipe bang. Just one bang each time, & it only does it when the tap is on hot (Mono tap with 10mm tails).

I have held each pipe to feel for movement, all pipes are clipped & I have no idea where the noise is coming from. Could it be a faulty TRV?

petertheplumber12 · 3 Jun 2013

It could be an unsupported pipe somewhere else in the house. If you turn the tap off slowly and it doesn't bang then you need to find where it is doing it. water hammer transmits for a good number of metres from source.

Dan Robinson · 3 Jun 2013

TMV.... not TRV.... God that baked my brain for a moment...

Anyway, as with Pete. Unlikely the valve. More likely an unsupported by or a dodgy flush valve in a loo.

Charnwood · 3 Jun 2013

As I have said before. As a counterboy Iheard it all.
TRV, to some, also stands tor Thermostatic Regulating Valve, meaning a TMV.

Try clipping the pipework immediately before and after the TMV (3 clips) to stabilise it. This must be the cause as it is the only difference to the pipework, you've just added a lump of brass to it.

SMG · 3 Jun 2013

The feed pipes are behind the plasterboard wall, behind the units, its impossible to access them. The only way I could "Stabilise" them would be to drill a few holes, very carefully, & inject expanding foam in, I was kinda hoping the valve was duff.

One thing I don't understand is why the pipe doesn't bang when the TMV is not in place, why would fitting the TMV "create" this effect?T

hanks guys.

(TRV.My bad, should have been TMV)

SMG · 9 Jun 2013

Just a quick update. I replaced the TMV with another, same banging, fitted another TMV in the upstairs bathroom, lo & behold, more pipes bang. For some reason the TMV is creating the fault, the hydraulic shock,

Without the mixing valves there is no pipe hammer at all? Very strange.

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Pipe banging

SMG

petertheplumber12

Dan Robinson

Charnwood

SMG

SMG

DIYnot Local

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