I am connecting a programmable thermostat (Hunter 44760 to a Trane 2 stage Weathertron heat pump, I understand most all, BIG NOTE the Blue wire is Common to the 28vlt transformer. I’ve mapped all wires, Tan is is anticipator and not used, all other Color codes are the same.
Red - Hot side of 28vlt AC transformer
White - Heat Call
Yellow -Cooling Call (Stage 1)
Green - Fan
Orange - Reverse Valve (COOL/HEAT)
X2 - Black is Aux heat (Tie to Emergency )
Blue is COMMON on Trane - (Other systems its the oppisite of Orange)
There is one thing I’m a little concerned about before I “go for it”. My original thermostat BAYSTAT240 has an 82K resistor mounted on the heating mercury switch, does anyone know what this is for, and will the new thermostat have this internally?