Hi, have just had new single valve thermostatic shower fitted in new bathroom but we are unable to get it anywhere near hot enough. We prob only just have 1m head from hot water header tank and mains pressure supply to the cold. The shower instructions imply that by putting in the correct restrictor than it should be able to deal with the mismatch but it blatantly can't ( it says it can work with 0.1bar pressure). So, my question is will a dual valve shower help to solve things, a pressure reducing valve on the cold inflow or do we need to give up and try to work out how to raise our header tank? We aren't worried about huge flow/power just a bit more warmth!
One metre of head is insufficient to achieve anything other than a dribble from the shower head. Using cold at mains pressure with such minimal flow on the hot even with the white restrictor disk in place will absolutely not work with ANY shower.
The most logical way to improve performance is to increase the hot pressure by raising the header tank (not practical in most circumstances) or fitting a twin impeller shower pump and supplying both hot and cold to the valve from the low pressure system. - Or fit a combi boiler???
You have very unbalanced supplies. Cold at 3 bar and hot 0.1 bar. The capability of the shower doesn't matter and it isn't the shower's fault - the cold is just overwhelming the hot.
Disconnect the mains supply to the cold and run a new cold feed with a SEPARATE connection to the CWST from any other service.
That way both your hot and cold will be at the same pressure. Once you have done that you can determine if you need to consider raising the tank or fit a pump.
BTW the hot feed is SEPARATE from the supply to taps isn't it? What I mean is that a Surrey / Yorl / Warix flange has been used in the top of the cylinder to give separate draw off OR its separately piped out of the side of the cylinder.
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