How to replace thermostat cartridge

[zack6600]

Hi Folks, Need your advice on how to access a thermostat cartridge to fix/replace. Please see pics below. I have manged to to get the main shower control cartridge out as it is leaking badly. But now need to sort the thermostat/mixer out now as very stiff and difficult to turn to cold. The problem is I can't work out how to get the chrome surround off, which I am assuming I need to do to access it. It is the bottom one in third picture. Could anyone please advise?

 

[ShaunCorbs]

It undos / screws off/ friction fit with an oring

 

[SimonG]

Wrap a pair of rubber gloves around the chrome part and unscrew.

 

[zack6600]

It undos / screws off/ friction fit with an oring

Don you mean the decorative/brass collar? Can't get it to budge...

 

[zack6600]

Wrap a pair of rubber gloves around the chrome part and unscrew.

Thanks, will give a go

 

[zack6600]

Thanks, will give a go

Can't get to budge an inch. Any other tips?

 

[zack6600]

Have got chrome collar off, but now can't work out what to do next.

 

[Deleted member 120897]

Likely to need an adjustable spanner on the flat part of cartridge, or an open ended spanner if the correct size.

 

[zack6600]

Likely to need an adjustable spanner on the flat part of cartridge, or an open ended spanner if the correct size.

Yeah, have give it a go already and just can't shift it. Think it must have seized. Think I might have to replace the whole mixer system frustratingingly.

 

[Ric2013]

Second picture. Grub screw in the side needs removing before it will turn?

 

[zack6600]

Second picture. Grub screw in the side needs removing before it will turn?

Yeah, had already taken that out. I just can't get it to shift. Most annoying

 

[Ric2013]

Have you tried careful use of heat? Hot water, or, probably better, a flame.

 

[Timmy D]

Bigger spanner.

If using adjustable spanner, ensure a perfect fit to prevent rounding it off. Get a steel tube to put over spanner handle for more leverage.

I’ve never come across one that I’ve needed to heat or won’t eventually come out.

Show it who’s boss!

 

[Ric2013]

Sometimes the flat sections on the brass will round off even with a good spanner. In that case, a quality Stilson wrench may be usefully employed.

 

[Timmy D]

Sometimes the flat sections on the brass will round off even with a good spanner. In that case, a quality Stilson wrench may be usefully employed.

If you haven’t got a set of the Rothenberger R type wrenches, you’re missing out.

Once they’ve bit, they rarely slip. I’ve got them in 6”, 8” & 12”. The 6” ones are great because they close small enough for turning old seized stopcock/gate valve spindles.