Hi
I have an issue with both shower systems in my house alternating hot/cold when run - shower temperatures never actually get "scalding" hot, more like warmish before reverting to cold and back - I have tried adjusted both valves to improve with little luck, the only improvement I've had is reducing the flow on the mains feed with a ball-valve otherwise the cold seems to prevail completely. The basin taps however, both upstairs and down do get hot. I should note this wasn't always the case, previously before installing the second shower system, I had good temperature in the first shower. I've had Two plumbers check it over. My gut is that is that it may be related to a lack of pressure in the hot from the boiler. We have a strong mains feed pressure but also suffer from hard water here in the south-east.
System info:
Worcester combi-boiler, pipe diameter 15mm for hot and mains to shower and basin taps
Thermostatic shower valve: crosswater shower & bath valve PRO1500LBPV
