Posted 12 November 2023

Shower boiling hot - mixer broken, easy fix?

Hi all, our shower only has one setting, scorching hot! Adjusting the temperature on the mixer does nothing.

I have tried getting a plumber out to come have a look at it but so far been unsuccessful getting one out, probably as job too small.

Our shower is a mira gem 88 and the pressure is amazing on it, would rather fix it.

Anyone with experience able to assist whether it is fixable or will need to be replaced?
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  1. hoorah91's avatar
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    Cheers everyone for the help so far. Right I've got the front off and got it down to this bit. Trouble is when I start unscrewing, water starts coming out of the shower, anyone know how I would isolate this? Thanks (edited)
    TristanDeCoonha's avatar
    Main stopcock outside
    Or
    Stop valve under the bath
    Or
    Anywhere in between
    But take the hose off or it will back flow as soon as you let air in. At least you can control the mess
  2. jameshothothot's avatar
    i had a similar problem - was able to change hot water setting on my boiler until it got fixed.
  3. psychobitchfromhell's avatar
    Mine did the exact opposite in that it stayed cold. Replaced the cartridge inside and it was fine after that. Fairly straightforward job, took about five minutes.
  4. TristanDeCoonha's avatar
    Have you tried pulling your knob off and checking the condition of the splines? You might be twisting your knob but it might not be turning the plastic inside.
    Are you in a hard water area? Perhaps limescale is an issue. Take it off and run some descaler through it. Something that should be done once in a while anyway, as a preventive measure
    hoorah91's avatar
    Author
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    No, struggling to find any guides online, can't even figure out how to open it!
  5. AndyRoyd's avatar
    Temperature pointer should "just" come off with semi-aggressive pull / gentle assistance levering between temperature ring.
    Any activity involving a lever may best be performed in a discreet location, such as from below / least visible section of component(s).
  6. hoorah91's avatar
    Author
    Today I got round to changing the shower cartridge, seemed to go fine and looks to be installed right but the water is still boiling hot and no cold 👎
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