Repairing a Shower Thermostatic Valve

[awemawson]

The control knob assembly on our shower in our 'En Suite' has been playing up for quite some time. Rotating the lever to increase the water volume it was jerky, and to decrease the volume it had to be rocked back and forth before it would return to zero flow.

It 'felt' as though O rings were bunching up and needed to reverse a bit to relax. Now some time ago we had a chap in doing some other plumbing work and he very helpfully provided dozens of flyers for other controls that he could fit but none of them had the same mounting centres for the pipework emerging from the tiled walls, so we've been "struggling on" not wanting to disturb the tiles.

Now the shower tray has started leaking so time to properly sort things out. Quote received to replace shower tray, and quadrant shaped enclosure which would be a good time to fit a replacement mixer valve as some tiling would be replaced anyway (I still have two boxes of tiles from when the en-suite was built a decade ago so no issue matching)

But then I found an outfit offering replacement 'innards' for mixer valves (original no longer available) if I could give them photos of the valve. Well this went through several iterations wanting more and more dismantling for photos, until this morning I had the entire thing apart - will it go back together 

So as it was apart I gave it a good clean up to remove the small traces of 'water hardness' calcium - our water is pretty soft but after so many years there was a bit on some of the revolving co-axial parts.

Dimensioned photo produced with spline details etc and I re-assembled it with a trace of petroleum jelly on the O rings and concentric rotating bits. A bit fiddly to get the temperature setting lever back to the correct range but . . . guess what . . .

. . . it now rotates ever so smoothly and seems to work fine . . . have they manoeuvred themselves out of a sale 

Now I've sent them the photo (below) and if they can identify a replacement I'll buy one, but it will sit on the shelf as a spare while the original gets a more prolonged test.

[Sea.dog]

I've stripped and cleaned the very same unit, Andrew. For the life of me I can't remember who made it. I'm pretty that it was one of the larger concerns.

Showerdoc is a good source for parts.

[awemawson]

Having seen my document they've come back with a suggested replacement which I've ordered. It's on 14 day return - just as well as it was over a ton 

[hermetic]

looks like an early Mira Andrew, I am surprised that there are no parts available, they used to be the rolls royce of showers, but they are very sensetive to calcium or grit in the water and as you have found out, it only takes a tiny amount!
Phil

[awemawson]

The replacement arrived by post this morning and looks to be the correct thing - impressively quickly. I've decided that we'll fit it when the shower tray and cubicle are changed and keep the old one as a spare. That way I can check that my 'repair' has worked over the next few days before the plumber can fit us in.