Irratic thermostatic shower from combi boiler

[CRAIGNEWHAM]

Morning,
We have a thermostatic shower that runs hot, then cold and then hot again. Seems to happen every couple of minutes, but more so when the temperature is adjusted. It has a check valve fitted and the hot water for the bath is always hot. Anybody have any ideas? Should I fit a pressure reducing valve?
It runs off a combi boiler. It did it with the old thermostatic shower too so dont think its that.
Any help appreciated, thanks

 

[Mike Jackson]

Could be a boiler fault. What make and model is the boiler?


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