nest Learning Installation & Configuration Manual page 14

1 Stage Heat Pump with Aux heat and Emergency 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:​ ​ W 3,​
Rh 24VAC power from heating transformer ‡
2 Stage Heat Pump
Label: Function:
Y1 Compressor Relay (Stage 1)
Y2 Compressor Relay (Stage 2)​
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 ‡
​ A uxiliary Heat Relay
E​ , HUM/DHUM, 3rd-speed fan
, 2nd-speed fan
A uxiliary Heat Relay
relay
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