nest Learning - 2 Stage Heating;Cooling Diagrams

Conventional 2 Stage Heating, 1 Stage Cooling

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 ‡


Conventional 2 Stage Heating, 2 Stage Cooling

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 ‡




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