it is possible that you have not calibrated it correctly when refitting the new cartridge. turn the dial to fully hot
remove the calibration ring and turn it back in mid air then refit, this will give you a higher temperature range.
if you don't have the fitting instructions go to Miras own website click on support then then on installation guides select your shower from the drop-down boxes there you will find the complete installation guides including how to calibrate the shower
Toptrish
January 2013