Concealed shower not getting hot

[Matt0029]

Can this be anything other then the thermostatic cartridge? What stops it allowing the hot water side through. Thanks

 

[Chuck]

Is there a filter/strainer or a non-return valve on the hot supply to the shower?

Is the hot water from a combi or cylinder?

 

[Matt0029]

It's from a cylinder. Everywhere else is getting hot water.

 

[Matt0029]

All the pipework is concealed so not sure about a non return valve