3rd Gen. Nest Learning thermostat compatibility

[Rex123]

Got a  new 3rd Gen. Nest Learning thermostat to replace a Honeywell Home ProSeries (TH4210U2002)  thermostat , got 6 wires on the Honeywell  thermostat connectors, Y , G , C, O/B , R and  on the sixth connector with two labels , AUX-W2.

Could someone please tell me if the Nest thermostat is compatible with my HVAC system?

[David_K · Accepted solution]

It sounds like you have a dual fuel system, like a heat pump and a furnace. Based on those wires, it should be compatible with any model of Nest Thermostat.