Thermostatic mixer failure and leak following new boiler installation

[tarkboffin]

Hi,

We had a new combi boiler fitted this week, changing from a system boiler and water tank. The work did not touch the bathroom area. The first shower with the new boiler the concealed mixer failed and caused water to flow through the ceiling below. The mixer failed when I activated the stop button on the showerhead. The mixer is a old unit that the previous owners put in, possibly up to 15 years ago.

My question is, is this pure coincidence or bad luck, or is there something that might have happened during the installation of the boiler that would have caused this?

Many thanks
TB

 

[Stigster]

Shower valves are manufactured for either low pressure (gravity) systems or mains fed systems. i.e. Low pressure or High pressure specification.

When converting a gravity fed system to a mains fed system, as you have had done, the pressure rating of any outlets must be taken into account. Some valves and taps can cope with either/or but others cannot as you have unfortunately found out.

 

[ShaunCorbs]

Agree with the above installer should of warned you at the very least

 

[king of pipes]

Your installer should of at least made you aware of the shower mixers suitability. Kop

 

[townfanjon]

This can be a problem with guys or firms who just install boilers and realistically arent heating engineers or plumbers , schoolboy error that you were not advised .

 

[tarkboffin]

Thanks for the feedback, guys. It's there a UK trade body recommendation or something similar where this is officially advised or written down? If I want to discuss liability with the installer this would help.

Cheers
TB

 

[Chuck]

The first shower with the new boiler the concealed mixer failed and caused water to flow through the ceiling below. The mixer failed when I activated the stop button on the showerhead.

What make / model was the mixer?

A low-pressure mixer might not work properly with a high-pressure feed, e.g. dripping but, to me, this seems more likely to be a below-par concealed joint made when the mixer was installed. Failure due to the higher static pressure added to the shock associated with suddenly stopping the flow through the shower.

 

[tarkboffin]

Hi,

The mixer is a concealed Hydromax, but until I have it taken out I don't know which colour. The leak only occurs if I turn the shower on.

I've had input that the previous system may have been high pressure anyway "However, in this instance you already had a pressurised hot water system by virtue that you had an unvented hot water cylinder.".

I may have to wait and see what has failed once I can get a plumber out to take it all apart after Xmas. Thanks for all your advice!

TB

 

[JCplumb]

So it's a concealed unit, how could the installer know if there were any issues with it, imo this is just bad luck.
How many boiler installers would take the face plate off a bathroom mixer to have a look at it (not that looking at it would tell you anything useful, you'd need the original documentation that came with it).
You had an unvented before so no pressure increase, this is just unlucky, same kind of situation as a stop tap gland leaking after work done somewhere else on the water system.
I can't blame you for wanting to know if it was the boiler installers fault, but I really don't think it is.

 

[moonlight]

If you have a Mira excel shower the cartridge will need to be changed. The gravity one will not hold out with a combi.