Latest Nest Thermostat GA01334-US G4CVZ heat pump wiring (not Learning model)

[Drewc]

My nephew moved into a new home that has two Honeywell thermostats. He would like to switch both to the Nest Thermostats GA01334-US G4CVZ. This latest Nest model only has 6 wire terminals: Y, C, W, G, R, and OB.  The downstairs is a Honeywell thermostat model TH6110D102 and has the standard 5 wires connected to terminals R, Y, C, W, and G. I went into the installers menu by holding down the Fan and Up arrow for a few seconds and it lists setup function 1 is set to 0 which is Gas, oil, or electric heat with A/C. I know the Next Thermostat will work for that.

The upstairs thermostat is a Honeywell model TH6220D1002 and he has a heat pump for the 2nd floor and I think also an electric heater in the attic as aux. based off installer code 6 set to 9 (2nd stage heat cycle rate is 9 for electric furnaces) as described below. He didn't have a ladder to get up into the attic to verify. It has these 6 wires connected to the Honeywell thermostat:

R and Rc have the jumper wire installed.

R - red wire
Y - yellow wire
C - blue wire
O/B - orange wire (installer code 2 set to 0 for O engerized for cooling)
G - green wire
Aux/E (one terminal, not two separate) - white wire

The Honeywell installer codes are:
1     5 - 2 heat/1 cool
2    0 - O/B - O is energized in cooling if set to 0 (zero)
6    9 - 2nd stage heat cycle rate is 9 for electric furnaces
9    3 - compressor cycle rate CPR (3 is default)
15  5 - compressor protection 5 minutes

The Nest compatibility checker says the Nest Thermostat is compatible with this setup. The side of the Nest Thermostat box in the store says: The Nest Thermostat can control one stage of heating and cooling, and a second stage of either heating or cooling; heat pumps with aux. or emergency heat; and fans, one speed. The * (OB) connector can accept only one of these wires: Y2, W2, or O/B.

My question is on the existing Honeywell thermostat with the 6 wires listed above, there is an orange wire on O/B and a white wire on Aux/E. Would the orange wire go to the * OB connector on the Nest and the white wire to the "W" on the Nest? As stated above, the Honeywell installer code lists 6 set to 9 with 9 defined as 2nd state heat cycle rate for electric furnaces.

Another question, does the Nest setup ask you if O/B is energized for cooling or heating like in the Honeywell where installer code 2 is set to 0?

I tried adding the Google Home app and adding a thermostat but you have to have a QR code or 6 digit code from the actual thermostat which has not been purchased until I verify compatibility with the Nest. It would be nice to be able to walk thru the options before purchasing the thermostat.

[zoeuvre]

Hi Drewc, 

Thanks for posting here in the Community forum and for showing interest in our Nest Thermostats. Based on the information you provided, here's how you can connect the wires from the existing Honeywell thermostat to the Nest Thermostat:

1. Downstairs Thermostat (Honeywell model TH6110D102):
   • R (red) wire goes to the R terminal on the Nest Thermostat.
   • Y (yellow) wire goes to the Y terminal on the Nest Thermostat.
   • C (blue) wire goes to the C terminal on the Nest Thermostat.
   • W (white) wire goes to the W terminal on the Nest Thermostat.
   • G (green) wire goes to the G terminal on the Nest Thermostat.
2. Upstairs Thermostat (Honeywell model TH6220D1002):
   • R (red) wire goes to the R terminal on the Nest Thermostat (excluding the jumper wire installed between R and Rc).
   • Y (yellow) wire goes to the Y terminal on the Nest Thermostat.
   • C (blue) wire goes to the C terminal on the Nest Thermostat.
   • O/B (orange) wire goes to the *O/B terminal on the Nest Thermostat.
   • G (green) wire goes to the G terminal on the Nest Thermostat.
   • Aux/E (white) wire goes to the W terminal on the Nest Thermostat.

Regarding your question about the * (OB) connector on the Nest Thermostat, the orange wire from the O/B terminal of the Honeywell thermostat should be connected to the O/B terminal on the Nest Thermostat. The white wire from the Aux/E terminal of the Honeywell thermostat should be connected to the W terminal on the Nest Thermostat. During the Nest Thermostat setup, it will guide you through a series of questions to configure the system. It will likely ask about the type of system (heat pump with auxiliary heat) and whether the O/B wire is energized for cooling or heating. Make sure to follow the on-screen instructions during the setup process to correctly configure the thermostat. Also, it's not possible to walk through the options in the Google Home app without the actual thermostat or its unique code. You may need to purchase the Nest Thermostat first and then follow the provided instructions for setup. Remember to turn off power to the HVAC system before making any wiring changes, and if you're unsure or uncomfortable with the installation process, it's recommended to consult a professional HVAC technician to ensure proper installation and configuration of the Nest Thermostat.

Let us know if that helps.

Best,

Zoe