Mira Excel Cartridge

6 Nov 2007
Reaction score
United Kingdom
Hi everybody. On returning from a holiday my mira excel was running lukewarm no matter what temp i turned it to. On reading up on internet and advice from an engineer i was told i needed to replace my cartridge.

On replacing the cartridge the shower is still only really running warm when normally 2 on the temp gauge was hot enough before. The shower is drawing hot water from the combi (worcester 24)

Could anything have happened in the week it wasnt running maybe? Is the factory set temp normally hot enough or would i be better of trying to adjust it on the new cartridge or any other ideas or maybe just call a plumber in.?

I recently had my hot water tank taken out so the shower is fed with mains pressure now. Could the problem be down to unbalanced inlet pressures due to the mains being a lot more than the combi boiler. The plumber that done the work said that maybe a presure reducing valve maybe needed but he didnt fit one. The shower would also squeal sometimes and the handle to turn it on and off would be stiff (which since knowing little about plumbing i put it down to age since its just over 5 years old)

Cheers in advance
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I had exactly the same problem and also replaced the cartridge £100 with no real difference. I then surmised that it had to be the boiler and in fact that rapidly became apparent as the hot water started to fluctuate in temp and the gas would go out whilst hot water tap was still on. It would then come back on again but of course water was running hot and cold.
I tried a local Corgi man who suggested a power flush!! and seemed to have no idea. so on recommendation I called British Gas and the problem was a blocked plate heat exchanger and he also changed the diverter valve as he thought it was dodgy.
Now the shower is back to normal - well not quite as I discovered the reason why it used to be hot enough on blue was to do with the pressure switch on the back of the cartridge (special tool comes with new cartridge). It was set to high pressure and by adjusting it back slightly I now get hot water on no 2, I know I could make it be hot on no 5 or so but I can't be bothered taking it out again.
Incidentally no-one was able to tell me this even though I spoke to Mira and went on numerous forums.
I would be pretty sure the problem lies with your boiler and I would expect you to see some hot water issues as well.

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