Once installed, Nest Thermostat can control: Cooling: 1 and 2 stages (Y1, Y2) Heat pump: with auxiliary and emergency heat (O/B, AUX, E) Fan (G) Power (C, RH, RC) Humidifier or dehumidifier (HUM, DEHUM) Heating: 1, 2 and 3 stages (W1, W2, W3) The Nest Thermostat’s connector can accept only one of these wires: - W3, E, HUM or DEHUM. WARRANTY