4 Wire Room Thermostat Wiring Diagram. Repairing electrical wiring a lot more than any other household project is about protection. It is not used not required to make digital stats work.
This is the earth which is unlikely to be required on the new stat. S indoor and outdoor wired sensors y compressor stage 1 cooling y2 compressor stage 2 cooling g fan c common u humidifier dehumidifier or ventilator control la a input for heat pump fault ob reversing valve for heat pump systems e emergency heat. Common 1 red q11 demand 2 yellow q12 or q14 if you want to try it none 3 not used neutral 4 blue not used first of all please forget the neutral blue wire on pin 4.
Whilst the sunvic circuit diagram shows the connector numbers 1 3 and 4.
This is the neutral. Honeywell dt90e room thermostat wiring diagram. This is the earth which is unlikely to be required on the new stat. Otherwise the arrangement wont work as it ought to be.