I have a Main Combi 24HE boiler. My current thermostat has only 4 wires: 1x Black 1x Red 1x Yellow 1x Earth. Could someone help me with what wire goes to what connection on the Hive 2 single channel thermostat. Am I correct in thinking the red is Permanent live, Black is permanent neutral with yellow being the heating on (almost switch live return to the boiler). There is no hot water control from the thermostat end. Do I have to install the hive receiver in the boiler cupboard with new wires? Hope someone can help? Many thanks!