Nest 3rd Gen Learning Thermostat Wiring

[KoryNichols4]

I have a Nest 3rd Gen Learning Thermostat. I’m trying to figure out the correct way that it should be wired. I have an all electric system with a heat pump and heat strips (auxiliary heating). 

My current configuration is: 

• Yellow Wire in Y1
• Green Wire in G
• Orange Wire in OB
• Red Wire in Rc
• White wire in W2/Aux (shows a brown wire on the configuration)
• Blue wire in C

I’ve seen other configurations recommend the white wire be placed in the W1 slot (it avitally shows white wire in the configuration when in the W1 spot rather than a brown wire when placed in the W2/Aux) and some recommend the white wire be placed in the * spot for emergency heating. 

What would be the correct configuration for my set up? 

Also, I have the orange (heat pump) wire in the OB spot. However, when I tried to run the heat, there was no warm air coming from the vents. I used an infrared temperature gun and it show 50 degree air. I switched the setting on the thermostat to “B” instead of “O”, and hot air began blowing, but it is an orange wire. So, I’m not sure why I’m having that issue. 

Thanks for any help. 

[KoryNichols4]

This is my current configuration. 

[zoeuvre]

Hi KoryNichols4, 

Thanks for posting. For your all-electric system with a heat pump and auxiliary heating, the correct configuration for your Nest 3rd Gen Learning Thermostat wiring is as follows:

• Yellow wire: Connect to the Y1 terminal.
• Green wire: Connect to the G terminal.
• Orange wire: Connect to the O/B terminal.
• Red wire: Connect to the Rc terminal.
• White wire: Connect to the W2/Aux terminal.
• Blue wire: Connect to the C terminal.

Regarding the issue with the orange wire in the O/B terminal not providing warm air, it's possible that the reversing valve in your heat pump system is wired differently. In some systems, the reversing valve is energized in the cooling mode (O terminal), while in others, it's energized in the heating mode (B terminal). To determine the correct setting for your system, could you help me with the make and model of your heat pump system so I can take a closer look? 

Keep us posted.

Best,

Zoe

[KoryNichols4]

Hello Zoeuvre, 

Thank you for confirming that my wire configuration is correct. I appreciate it. As far as the issue with the O/B, I have a Ruud unit. I did find out after posting this that Ruud units do energize the reversing valve in the B terminal. Thank you. 

[zoeuvre]

Hi there, 

Great! I'm glad that everything has been sorted out. If you have questions or concerns in the future, feel free to start a new thread, and we'll be happy to help.

Regards,

Zoe