shower doesnt get hot : Vaillant turbomax plus

[rjkbe]

I am sure this has come up before so apologies if there is already a solution.

My Clearwater thermostatic shower (and bath) will not get hot but the kitchen and bathroom basin taps are more than hot enough. Someone suggested it may be a diverter problem with the boiler. But if other taps get hot, is this likely - or is the diverter only for the shower/bath mixer?The system was working OK during the summer but when the cooler weather arrived, it has stopped even though I have not had the CH on until recently (and that works OK).

Hot water is getting to the shower - I turned off the cold inlet to the shower valve using the screw on the shower valve housing and water then came through the shower at the same temperature as the other taps. I then opened the cold supply to the valve so that a much lower flow comes out compared with the hot water inlet - any higher and all I can get is freezing water through the shower! With the thermostatic valve turned up above the red stop button, I now get a lukewarm shower. If I turn the valve back to the normal setting, the shower goes cold. I think I have tried to adjust the thermostatic element to its hottest setting although I am not sure if I have done that right - but that may not be the problem at all.

All ideas gratefully received.

 

[seco services]

sounds like you have a sticking cartridge in the shower valve.
turn it to hot/cold a few times can free them sometimes.

 

[rjkbe]

Thanks Seco. Tried turning on hot and cold several times and it didn't make a difference. Also, there is no evidence of limescale in the cartridge. Does it sound more like a cartridge problem than a boiler problem?

 

[buck51]

My guess is you have, mains cold and tanked hot, fit a PRV to the cold!!!
Or you have hot cold connections crossed,