Bath shower mixer tap valve identification please

Hi,
I have a tap with shower attachment on a bath and the shower is becoming increasingly difficult to shut off. The central knob just controls the flow and temperature to the shower head. The taps control the flow into the bath and there is no diverter valve. The unit is Twyford but don't know the model and I've not managed to find anything similar for sale today. I'm guessing it's about 20 years old.

I'd be quite happy to change the whole tap unit but it's been plumbed on the far side of the bath, against the wall and there's no way to access the underside of the bath without either moving the bath away from the wall or accessing through the wall from to other side. Both would be non trivial.

So I wondered about replacing the valve/cartridge but I'm not sure if I'd be able to source a replacement. In order to remove the valve, it looks like I need a deep 29mm socket (like this ?); I've tried removing it with an adjustable spanner, after having applied penetrating oil and I'm in danger of rounding off the nut.

Am I taking the right approach and any hints on how to source a replacement valve?

Thanks,

Graham.

Try showerdoc.com.

What does it say on the tap heads?

Just seen you mention Twyfords, a decent pair of grips would undo that.

Andy

graysd said:

I've tried removing it with an adjustable spanner,

Click to expand...

Try turning it the other way
https://www.showerdoc.com/mira-extra-bsm-post-1999-shower-spares

Excellent - great find! That does like my shower and it does indeed appear to have a left hand thread for the head assembly. Thanks very much

Next question, given the issue I have is that the handle needs a lot of pressure to turn it to completely stop the flow, which part(s) should I be considering to replace?

Thanks,

Graham.

the "headwork assembly" is known to seize up https://www.showerspares.com/search/mira-realm-v6-headwork-assembly-122.66/
Also available on ebay etc.

if you can get the headwork assembly & the rest of the thermostatic valve out of the tap. Undo the headwork and reattach the knob.see if it easy to turn by hand pressure by turning the knob whilst holding the headwork It should turn under light hand pressure.

But,its an old tap/shower mixer with many vintage (expensive) parts. There could be scale inside the tap body or valve train mechanism affecting the shower valve turning action. Tbh its not a repair job many proper plumbers would take on.

There were sold under many badged names. Meynell,Mira,Twyford etc. Although they are made by a different company .

For an equivalent item with modern thermostatic innards,consider the aqualisa aquamixa

good luck

I just wanted to say that I removed the old head assembly with no issues using a proper socket and crucially, turning it the right/wrong way. I then cleaned as much of the intervals of the tap as I could and fitted a new head assembly and that appears to have resolved the issue. Hopefully it will last until the rest of the bathroom needs a proper refit.

Thanks for your help.