Do you have temperature details for the settings on Drayton RT212 thermostatic radiator valve?
Do you have any table for settings, 1,2,3 etc compared to the degrees celcius it responds to?
The only info available is that it has a wax sensor and the operational range is between 10 to 27 degrees centigrade. The only way to do it is take number of gradients and divide that into 27 and each gradient is that number of degrees.