Bristan shower mixer

[GB]

I have a Bristan thermostatic shower mixer, which is only giving out a meagre amount of not very hot water. I suspect that it has got furred up inside. Is it possible to do anything about that, short of buying a new one?

Also, I have not been able to find any isolation valves. I take it that these mixers don't have automatic valves in them that shut off the water if the central hub part is removed for servicing?

[A.Lee]

Here for the spares:

may have a cartridge assembly that needs replacing, though it could be just limescaled up.

Thats right, no isolation valves inside the unit. With the water off, it'd be a good time to fit new iso valves. Get the full bore version for showers, not the cheaper one that restricts flow. Alan.

[GB]

Thanks - both answers are brilliant!