Fitting temperature stop concealed shower

[Matt0029]

How do you set this on a concealed shower cartilage is it ment to be so that when the shower is at its hottest the knob is at the 12 o'clock position. Then you have to press the button on to move it further. So the shower goes hotter then 38degrees c.

 

[Matt0029]

It's a a line on the splines wondered if this was anything to do with it?

 

[ShaunCorbs]

Use a thermometer to set the temp before putting the dial on eg 38c set dial to 38c etc