Shower control stiffness

[hollymcr]

I had a Mira thermostatic shower mixer which was in the house when we moved in. It worked fine for a couple of years but started to become stiff, particularly when trying to turn the shower off. It eventually became unusable so I bought a servicing kit and replaced all the washers and seals, and it was like a new shower!

However that only lasted a couple of months, and when it got bad the second time I replaced it with a new (relatively cheap) thermostatic shower mixer.

That was a few months ago and now the new one is getting stiff.

I'm looking to fit a new bathroom this year but I want to get to the bottom of this first. What is it likely to be and how do I check?

Other info: it's a power shower, and the pump feeds a second shower (identical Mira unit to the old one we replaced) and that's fine, but it's not used very often so that doesn't mean anything. I'm not aware of any particular limescale issues but I guess it's only really the shower that uses hot water so it could be hot water tank specific? In case it's not obvious I'm not a plumber!

 

[Madrab]

Pull it apart, you'll soon see if it's scaled up or not. Usual check is do you get scale in your kettle?

May need a bit of silicone grease on the brass to ease up the moving parts.

 

[hollymcr]

Scale in the kettle: yes, but not a massive amount (although I have a wire mesh thing in there to collect it so I'm not sure I could tell).

I am in a hard water area based on my postcode though 252ppm if the online lookup is accurate).

I haven't taken the new one apart but the old one had scale in it but again not a massive amount (but I don't know how much it takes). I see adverts for Calgon on telly showing really badly furred up washing machines and its nothing like that!

Do hot water tanks need flushing out periodically? (If so, how?)

Would a SESI on the outlet from the hot water tank help? Or indeed on the mains incoming supply?

Thanks for the advice!