Therm. Shower Valve temparature dropped

[Wane Tines]

Hi to all. I have a thermostatic shower valve which has operated perfectly for about a year and a half since I installed it. The flat is served by a Vaillant Turbomax combi boiler. All other hot taps are fine but the temperature from the shower suddenly won't rise above lukewarm. I checked the filters in the valve but they seemed ok - a little debris but not much. Any ideas on how this could be fixed would be much appreciated as the valve is concealed behind tiles and replacing could be a real headache.
Cheers.

 

[chrishutt]

You need to check that the hot water from the combi is at a much higher temp than the water coming out of the shower. If so, it's probably a fault with the shower (scaled up mechanism, failed thermostat?).

 

[Wane Tines]

Many thanks. Do you have any idea if that would be fixable without replacing whole valve?

 

[Wane Tines]

Actually, I think the water from all taps is cooler than it should be although hotter than the shower. Not sure how to check - it could just be my imagination...