Wiring Diagrams: Heat Pump Systems - nest Learning Installation & Configuration Manual

Wiring Diagrams: Heat Pump
1​ S tage Heat Pump
​
Label: Function:
Y1 Compressor Relay (Stage 1)
Y2 Compressor Relay (Stage 2), 2nd-speed fan
relay
G Fan Relay*
O/B Heat Pump Changeover Valve
Rc 24VAC power from cooling transformer
W1 Heat Relay (Stage 1)
W2/AUX Heat Relay (Stage 2) / Auxiliary Heat Relay
C 24VAC Common Wire †
* Star:​ W3, E, HUM/DHUM, 3rd-speed fan relay
Rh 24VAC power from heating transformer ‡
1 Stage Heat Pump with Aux Heat
Label: Function:
Y1 Compressor Relay (Stage 1)
Y2 Compressor Relay (Stage 2), 2nd-speed fan
relay
G Fan Relay*
O/B Heat Pump Changeover Valve
Rc 24VAC power from cooling transformer
W1 Heat Relay (Stage 1)
W2/AUX Heat Relay (Stage 2) / ​
C 24VAC Common Wire †
* Star:​ W3, E, HUM/DHUM, 3rd-speed fan relay
Rh 24VAC power from heating transformer ‡
Systems
A uxiliary Heat Relay
12