Thermostatic mixer shower

[Gary]

I think ours is on the way out. It doesn't really get hot any more despite the hot water temperature in the taps being more than hot enough.

It's gravity fed from the hot water tank and a header tank in the loft (fairly certain of this). I'm not sure what model the shower is as it was fitted by the builders when the house was built 6 years ago. This means it was probably cheap.

How easy are these kind of things to change? For one who knows nothing of matters plumb?

Is it possible it has scaled up internally? I recently had to change the shower head due to lime scale.

[Andy Burns]

Had similar with my Mira Excel recently, had changed the "cartridge" this year and it had been ok until recently (suspect either colder weather leading to colder water supply, or central heating being on more leading to raised hot water temperature compared to just a 30 minute hot water only timer)

With the benefit of an instruction manual downloaded from Mira, it turns you can remove the knob, and then internally turn the spindle to a hotter/colder range, before refitting the knob on it's splines, thereby shifting the temperature range up or down, this helped in my case, it's maximum is restored from "warm but not hot" to "scald a rhino" (ok, not really that hot, but you get the picture)

If you can easily disconnect the pipework above it and pour down some descaler and leave it for a while it could have an effect, I tried it before eventually replacing my "cartridge" though and it could only be described as having a small improvement

[Andy Burns]

cue the grammar police ;-)

[Roger Cain]

My Mira 722 started to become erratic. I had to get into the housing which contains the bimetal strip spiral (the thermostat) before I found it was encrusted with junk which stopped it coiling and uncoiling. Hacked the junk off with a Stanley and it is now all working OK.

[The Medway Handyman]

It could well be scale as others have said, but if you want to change them;

Turn the water off. Go up into the loft & find the big cold water tank. There may be a stop c*ck on the pipe going in (the one connected to the float valve). If so, turn it off. If not place a piece of wood across the tank & tie the float arm up with string so no water enters the tank.

Now open the cold taps in the bathroom & wait till no more water comes out - can take 15-20 mins with a big tank.

When no more water comes out, open the hot taps. Water should stop in a few mins.

If over bath, remove bath panel, or gain access to back of pipes. Buy one of these

or one of these of the time the pipes will meet up on old & new, if not you can always use flexibles a bath is usually more difficult because of the confined space.