The boiler was fitted 2 years ago it is an Avanta plus 35c it was fitted with a wireless remeha mechanical thermostat, which the dog chewed. I have disconnected the receiver which was in the boiler front which had 4 wires going into block X2 pins 1,2 3 and 5 and wired the isense into terminal...
Just purchased an isense wireless RF thermostat the instructions say to first change boiler to open therm, (no instructions in manuel to say how to do this) any ideas.