Stiff shower temperature knob - does anyone know the cause?

[Tom Bigglestone]

Hi all,
Would really appreciate any advice. My shower temperature knob/dial on the right has suddenly become so stiff it does not move. So now jammed on the hot setting (and it's not even as hot asit should be either).

It's relatively new - only installed about three months ago after a similar thing happened. Does anyone know if I can easily resolve it or do I need to get someone out?

Thank you!

 

[Ben-gee]

What is the source of your hot water?
I suspect it could be too hot, most cartridges stipulate a maximum of 65*C. If it gets too hot things distort.

 

[Aquarius]

Could be limescale buildup if you live in a hard water area

 

[Ben-gee]

Could be limescale buildup if you live in a hard water area

Unlikely in 3 months.

 

[WC1]

If you're in a very hard area it's surprising how quickly it builds up, especially if there's a drip onto the unit. I'd suspect either distortion as above or poor assembly causing friction and galling of the brass. Turn off the water, prize off the small end cap then usually a Philips will get the knob off and you can check for wear. Often there's a thin plastic friction shim between the body and the knob, check it's the same both sides - flow and temp.

 

[Tom Bigglestone]

Thanks very much for your advice so far. I'm in East London so a hard water area so that might make sense.