No heat from mixer shower valve

18 Sep 2007
Reaction score
United Kingdom
Hi all,

A couple of weeks ago, my shower stopped giving out any heat. Only Luke warm\cold. As the shower was a few years old in thought it was duff. I purchased a new one but that did the same. The manufacturer's engineer came out to look.
He said it was an imbalance between the hot and cold pressure. He took the shower off the wall and turned the water back on. You could see that the cold was fast flowing out of the pipe but the hot was markedly less so.
Does anyone have any suggestion as to what could suddenly cause this? I don't think it's a leak as there's no damp patches anywhere and the kitchen ceiling is still up! I have a Worcester Bosch combi boiler if that has any bearing.

Many thanks in advance.
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Hi. Pressure at the bath and basin when taps are fully open is different. Cold pressure is greater. I have mixer downstairs so cant really tell there.

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Yes, that's correct. It's consistent across shower\basin\bath.

Could there be something in the boiler restricting the flow of hot water or something? <-- complete guess!
you need a boiler engineer then, pity the plumber who installed it never tested the original shower first, something I always do on any appliance so there's no come backs
Gas engineer it is. At least now I know what the possible cause is. Is it a big job to clean\replace the heat exchanger?
have to wait for a gas engineer to answer that one, have you got a scale inhibitor fitted like a combi mate,if you're in a hard water area it's a must.
Thanks for your replies everyone. Turnsnmout the boiler is still under warranty so the Worcester engineer is booked to take a look.

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