Mixer Shower Temperature Issue

bloke91

Hi all,

I know it's not strictly money saving related, but wondered if anyone had any thoughts or suggestions on an issue I have with my shower.

The temperature is continually hot even when changing the heat control to the furthest cold setting.  It doesn't matter what you do it's always hot.

Any suggestions or idea's on root cause or things to try?

Thanks 

ThisIsWeird

Is this a recent development - was it working ok before?
Type of water and DHW system - combi, vented, unvented?
Does the temp control feel different to before - more rough, tight, loose, sticky, anything?
Hard or soft water area?

bloke91

Started within last few weeks.

Combi boiler.

Temperature seems fine in other taps etc.

Think my area is defined as a hard water area.

justwhat

thermostatic valve needs changing ... or just replace full mixer.

ThisIsWeird

bloke91 said:

Started within last few weeks.
Combi boiler.
Temperature seems fine in other taps etc.
Think my area is defined as a hard water area.

Most likely issue is a faulty thermostat, possibly caused by the scale build up, or possibly just reached the end of its life. Possibly it's just a blocked inlet filet, perhaps due to bits of scale.

Does it feel 'funny' when you turn it - scratchy, stiff, anything like that?

Anyhoo, the whole moxer bar is easy to remove - you just undo the two large chrome nuts at the back and lift it off. You will, of course, have to turn off the water supply first - does the shower have its own isolating valves, say in the room behind it - is there a cupboard there?

Then you can check over the mixer, check the inlet filters, even have someone temporarily turn on each supply and check that they flow correctly out the pipes.

If all looks good in the water supply side, and also the filters are clean, then your choice is to either repair the existing mixer, or replace the whole thing - very little difference in cost. I'd go brand-new, and. You can then dismantle the old one and try descaling the 'stat if you wish.

How DIYish are you?

Any idea of the make? You will need to check the inlet pipe spacings, but almost certainly a large number of shower mixers will fit. You can get whole thermo mixers from around £25.

Protect the chrome finish on the nuts by placing card or cloth in the jaws of your spanner. I'd personally recommend a wee tub or tube of silicone grease, too, and give the washers and threads a smear before refitting.

moneysaver1978

Have a look at this thread https://forums.moneysavingexpert.com/discussion/comment/80964318 in case this helps but looking at the photo (and the rust), I think it would be easier to replace the mixer.

In our case, the heat control was completely stuck and it was easier and cheaper to replace the whole thing. When I took apart the old mixer, there was so much limescale inside and it was a faff to unscrew to access the cartridge so replacing the whole mixer was a good call.

The main thing is to measure between the central valves (standard is generally 150mm but good to check!).

Albermarle

ThisIsWeird said:

Is this a recent development - was it working ok before?
Type of water and DHW system - combi, vented, invented?
Does the temp control feel different to before - more rough, tight, loose, sticky, anything?
Hard or soft water area?

A new type ?

ThisIsWeird

D'oh - auto-corrcet. 

Belenus

Try turning the temperature control from one extreme to the other (fully hot to fully cold) multiple times while the shower is running.

That might or might not work.

Our not dissimilar shower manual advises doing that occasionally.

Albermarle

Belenus said:

Try turning the temperature control from one extreme to the other (fully hot to fully cold) multiple times while the shower is running.

That might or might not work.

Our not dissimilar shower manual advises doing that occasionally.

We live in a hard water area. When we had a new shower fitted the fitter advised not to leave the temperature knob in the same place all the time and to regularly move it, or it could seize up.

pieroabcd

Hold on, are you saying that there's a thermostat in the mixer? One more delicate component that can break any time? This comes as a shock to me. 
I have the same problem with a different mixer. I think that I'll choose something purely mechanical and old style. Tried and true.