Replacing thermostatic cartridge Bathstore Metro shower

[Cnocspeireag]

I have a bathstore supplied Metro thermostatic shower valve which no longer supplies hot enough water. I need to remove the thermostatic cartridge and clean or replace it.
Please excuse me if this seems too basic, but the brass cartridge clamp nut is stuck fast. It's a 38mm nut and is shown being removed with adjustable pliers in a demo video. This will not shift, using a Bahco adjustable wrench, even after applying PlusGas to the thread.
It seems that I'll need a large 38mm combination spanner to apply more torque. This tool will cost £45 or so. Does this seem sensible and is there a better method to free brass threads? The cartridge inside is partly plastic, so applying heat seems out.

 

[longdogs]

Have you tried tapping the wrench with a hammer?

Can you get a piece of pipe on the end to give you more leverage?

Try tightening it slightly first.

 

[Cnocspeireag]

Thanks for the suggestion, yes I did try tapping (gently, it was someone else's wrench). I had no success, the thing must have been assembled dry and without PTFE tape. The flats on the nut are quite narrow and the jaws of the wrench sprang off when I applied more torque, so the extension bar would probably not work.
It looks like the expensive combo spanner and a lump hammer! Of course I would never need the spanner again until the day after I decided to sell it.
Many thanks again for the reply.

 

[longdogs]

http://www.ebay.co.uk/itm/38mm-Extr...ltDomain_3&clk_rvr_id=822088150453&rmvSB=true

 

[muggles]

Are you sure spares are actually available for your shower? The disadvantage of Bathstore et al is that their after-sales often leaves much to be desired. You might have to buy a whole new shower!

 

[longdogs]

Are you sure spares are actually available for your shower? The disadvantage of Bathstore et al is that their after-sales often leaves much to be desired. You might have to buy a whole new shower!

Good point.

 

[Cnocspeireag]

Thanks again Squeaky, I hadn't looked further than my local MacGreggors and Screwfix.
Thanks for the comment Muggles; I hope so. The valve is by Crosswater and I understand cartridges are still available. There's a chance the cartridge might be cleanable as the builder responsible (since gone bust) employed some clowns towards the end and I've had several bills to fix their work already. I doubt everything was flushed through properly. I think it's worth a look before ordering a new part.
I know, I should have gone for MIRA.

 

[dingleberry]

I've had success in removing seized up nuts in the past by heating them up and then using a wrench. I spent hours trying to remove a nut once. I even banged the wrench beyond the point which was good for the part, but it didn't budge. I heated it up very briefly with a blow torch and voila, it turned because the metal expanded and loosened.

Just for future reference, the Bathstore Metro cartridge is still available - Thermostatic Cartridge for Bathstore Crosswater Kai Lever | Quatra Horizontal | Metro Vertical | Kusasi Shower Bath Valves

 

[75pete]

IF you can get a new nut and you really can't move it any other way, cut it across the threads ie corner to corner with a Jhacksaw. You will not have to go all the way, just some and then retry with the spanner .... Easy for me to say....good luck!

 

[alexlondon]

I am having a problem similar to that of the OP, ie I am trying to access the cartdridge in a metro valve.
I have removed the handle and the first collar but I am not sure how to remove the 2nd collar. See picture.
If I look at the instructions it is simply screwed on but I cannot unscrew it by hand. Do I need to remove the front panel first? This would also not be so easy becuase of the screws and the covers for the screws that I have not taken off before (they don't come off with a stanley knife) and of course having to replace all the silicon. Thanks for any help!