Cleaning/refurbishing thermostatic cartridge

[Donkmeister]

Hi all,
I've got a concealed shower valve from Victoria Plum. Recently the thermostatic control stopped working (hard water area, 4 years of service, not unexpected really) so I ended up buying an additional valve of the same design and swapping the internals over. It's now working again as it should.

I'm wondering if I can disassemble the old cartridge and descale the innards, replace any o-rings and then keep it as a spare for when it goes again in another 4 years... The cost of a cartridge alone makes it worthwhile, but there's also the possibility that parts might not even be available in 4 years.

But... I've got no idea how they work so I'm not sure if that's even feasible or if this failure means something has actually broken inside rather than just being seized up with scale. If it affects anything, the flow through the valve was just fine, it was simply that the temperature was locked at whatever I'd set it at before the valve failed. Before I expend the effort of trying to take the cartridge to bits, has anyone been successful in doing this?

 

[RandomGrinch]

I haven't (yet) replaced my thermostatic cartridge, but I have seen a video from a spare parts supplier, suggesting that the cartridge should just be left to soak in some descaler for an appropriate length of time.
The 'O' rings are then greased with silicone before reinsertion.

Although 'O' ring mutipacks are available, it's worth trying to find the exact size by measurement (allowing for wear); it wouldn't be good to have scalding water bypassing the wrong sized seal!

Video for reference, but not very exciting!

Give it a go!

 

[Donkmeister]

I've given it a good soak in citric acid now and boxed it up for the next time - we'll see!