nest Learning thermostat Installation And Configuration Manual page 13

Conventional 3 stage heating and 2 stage cooling Conventional 3 stage heating and 2 stage cooling Conventional 3 stage heating and 2 stage cooling
Label
Y1 Compressor Relay (Stage 1)
Y2 Compressor Relay (Stage 2)
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 connector: W3, E, HUM, or DHUM
Rh
24VAC power from heating transformer ‡
* Fan relay (G) is optional. However, without a G wire, Nest will not be able to control the fan independent of heating. * Fan relay (G) is optional. However, without a G wire, Nest will not be able to control the fan independent of heating. * Fan relay (G) is optional. However, without a G wire, Nest will not be able to control the fan independent of heating.
† † † Common wire (C) not required in most cases, but strongly recommended. Common wire (C) not required in most cases, but strongly recommended. Common wire (C) not required in most cases, but strongly recommended.
‡ ‡ ‡ Use Rh or Rc in single transformer systems; no jumper wire required. For dual transformer systems, use Rh for the heating Use Rh or Rc in single transformer systems; no jumper wire required. For dual transformer systems, use Rh for the heating Use Rh or Rc in single transformer systems; no jumper wire required. For dual transformer systems, use Rh for the heating
transformer and Rc for the cooling transformer. transformer and Rc for the cooling transformer. transformer and Rc for the cooling transformer.
Conventional 1 stage heating and 2 stage cooling Conventional 1 stage heating and 2 stage cooling Conventional 1 stage heating and 2 stage cooling
Label
Y1 Compressor Relay (Stage 1)
Y2 Compressor Relay (Stage 2)
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 connector: W3, E, HUM, or DHUM
Rh
24VAC power from heating transformer ‡
* Fan relay (G) is optional. However, without a G wire, Nest will not be able to control the fan independent of heating. * Fan relay (G) is optional. However, without a G wire, Nest will not be able to control the fan independent of heating. * Fan relay (G) is optional. However, without a G wire, Nest will not be able to control the fan independent of heating.
† † † Common wire (C) not required in most cases, but strongly recommended. Common wire (C) not required in most cases, but strongly recommended. Common wire (C) not required in most cases, but strongly recommended.
‡ ‡ ‡ Use Rh or Rc in single transformer systems; no jumper wire required. For dual transformer systems, use Rh for the heating Use Rh or Rc in single transformer systems; no jumper wire required. For dual transformer systems, use Rh for the heating Use Rh or Rc in single transformer systems; no jumper wire required. For dual transformer systems, use Rh for the heating
transformer and Rc for the cooling transformer. transformer and Rc for the cooling transformer. transformer and Rc for the cooling transformer.
Nest Learning Thermostat installation & configuration guide
Function
Function
Page 11