Problem with Crosswater shower thermostatic mixer valve

[nervous123]

Hi there, I hope someone can help. Ever since our bathroom was completely renovated 1/2 a year ago, we have had problems with our Crosswater shower thermostatic mixer valve. (all components brand new obviously)

The temperature water starts cold, and gradually increases in heat as the valve is turned, as per any normal shower.

However, this is only until the valve is turned about a third of the way (=mildly hot). Then it suddenly becomes scalding hot, and turning the valve back does nothing to reduce the temperature.

Can someone please confirm if this sounds like (a) the Crosswater cartridge is dirty/faulty; or (b) the hot and cold are plumbed the wrong way round. I'd much rather the former - I really really dont want to have to get tiles smashed up.

Many thanks!

NB. If relevant, we have an unvented sealed system and I have been told by a good plumber that the (bad) plumbers who fitted the system did not fit a balanced cold.

 

[Margo]

Hi nervous 123, I have exactly the same problem with my shower valve. Did you get a resolution ?
Thanks,
Mario

 

[flexiplumber]

problem shower

did your plumber check to see if the supplys (hot &cold) are connected the right way round,also there could be isolation vales somwhere that are not fully open,or it could just be down to calibration of thermostat, i do agree with the balanced cold being fitted when running two bathrooms of unvented cylinder but i cant see it causing your faults, let me know if pos.
regards flexiplumber