Shower Mixer Valve - Not so hot

[jonnydarcy]

Hi,
I moved into a new house a couple of months ago. The bathroom has a large head shower along with a separate hand held shower head. Each head has a knob dedicated to it's flow. Both heads share a temperature control with is a simply another knob which is manually adjusted for temperature. This presumably is a mixer valve.

The shower is boiler driven and has been in place for a number of years (to the best of my knowledge) and the hot water is forced through the unit via a pump. Until recently it's been a terrific shower but all of a sudden the temperature is barely able to get above luke warm.

The shower has only been like this for about a week now but oddly on one of the days the temperature went back up to almost what it was before.

Does anyone have any idea what this might be to do with? Presumably the mixer valve isn't working properly but why? We live in London so could this be a limescale issue?

The kind of unit we have is this:

http://www.ergonomicdesigns.co.uk/E...xer_Ceiling_Shower_Round_Massage_Jet_Set.html

I've managed to take off the taps with an alun key and a philips screwdriver but I can't see how I can get to see the mixer valve. Does the plate just pull away from the wall? Assuming I can get it off can anyone advise what I need to do?

The bath also has the same system and all works fine which is why I wonder if it's a limescale issue as we use the shower everyday but the bath rarely.

All help gratefully received.

 

[flameport]

Limescale is very likely, this can usually be fixed by removing the thermostatic cartridge (the part behind he temperature knob) and soaking it in descaler.
The limescale jams the mechanism so it gets stuck either on cold or hot.

If not, some types can be calibrated for various temperature ranges so may require some adjustment, or failing that the whole cartridge can be replaced.

Front plates usually just pull off, the cartridges either screw in or are held with circlips etc. - should be fairly obvious once the cover plate is removed.
Turn off both the hot and cold water first.

Another less likely possibility is that the pump has failed on the hot side only, so the pressure is now unbalanced with the cold being much higher pressure than the hot.

 

[jonnydarcy]

thanks flameport, brilliant.

If it is pump related would that not affect the bath also which too uses a pump (but which pumps out hot water with no problem)?

Am I right in saying the coverplate just prises away?

Thanks again

 

[flameport]

If it is pump related would that not affect the bath also which too uses a pump

Yes it would, so if the bath hot works properly, it's definitely the shower valve.

Am I right in saying the coverplate just prises away?

Looks like it, they usually do.
Only thing to watch is if someone has put silicone on the wall first and then pressed the plate into it - this will make it very difficult to remove.
If there is silicone sealant behind the plate, a long thin knife can be used to cut through it first (use a bread knife or carving knife) but be very careful not to scratch the plate or tiles.

 

[jonnydarcy]

Yes there's definitely silicone there which needs removing.

Will give it a go, thanks again.

 

[jonnydarcy]

Ok, so I managed to cut away the silicone and remove the plate. Not entirely sure what to do next. The middle brown plastic fitment does unscrew but only a few revolutions and stops.

Please see my uploaded photos.

The brass casing around this brown plastic fitment looks to have a thread but I didn't want to try and unscrew this without knowing what would happen. It also appears to be rather tight.

Any help much appreciated

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• jonnydarcy
• 17 Nov 2011
• 1

Untitled

• jonnydarcy
• 17 Nov 2011
• 1

Untitled

• jonnydarcy
• 17 Nov 2011
• 1

 

[oldoddjobber]

I too have an ergonomic designs mixer set.
I managed to solve the problem of getting the siliconed plate off the wall and got the cartridge out.
The valve was getting stuck when hot meaning that anyone suddenly feeling the shower too hot couldn't quickly reduce the temperature.

I have steeped the cartridge in vinegar, having got it hot in a bowl of very hot water. I've also squirted loads of limescale remover in as well. However the control still feels stiff when hot.

Ergonomic designs have discontinued this unit, although they can supply replacement cartridges - at a price! The trouble is I have two bathrooms and only been in use for a couple of years.

I suspect the design of the cartridge is not good and feel I would be throwing good money after bad.

I would appreciate any follow up info you might have to help me decide!