topic Re: Need additional wiring help for nest thermostat, please in Nest Thermostats

Need additional wiring help for nest thermostat, please

ctoles — Sun, 16 Oct 2022 19:35:27 GMT

I am having trouble figuring out where to connect the blue wire and the orange wire from my thermostat to the new Nest thermostat. The unit is a heat pump with both heat and cooling, Does the Blue wire go to the Nest C input and the Orange wire go to the Nest OB* input? photos below of current thermostat wiring. Thank you.

existing thermostat wiring

Re: Need additional wiring help for nest thermostat, please

Irishjedi — Sun, 16 Oct 2022 21:42:02 GMT

The blue is your Common wire. Put that in C on your thermostat. That will give constant power to the thermo. The orange looks to go into the OB.

Re: Need additional wiring help for nest thermostat, please

ctoles — Sun, 16 Oct 2022 22:54:22 GMT

Thanks for your quick response. I think I should have provided some additional information when i asked for wiring help, I want to make sure I wire the thermostat correctly. I have 2 heating/cooling zones in the house, one for upstairs and another for downstairs. The upstairs unit is a combo heat/cool/emerg heat heat pump unit with a dedicated air handler for this unit. The downstairs system is a gas furnace with an associated cool only heat pump unit and the downstairs has its own dedicated air handler. I am only wiring the nest thermostat for the upstairs heat pump. Considering this additional information, do I still not need the orange wire? It was connected to the 0 terminal with the old thermostat.

Re: Need additional wiring help for nest thermostat, please

Irishjedi — Sun, 16 Oct 2022 23:38:55 GMT

I only have a heat too and I didn't use the orange. I only used the red, white, and blue. Hope this helps.

Re: Need additional wiring help for nest thermostat, please

ctoles — Mon, 17 Oct 2022 11:39:51 GMT

The "heat pump" that I am wiring the nest thermo for provides cooling and heat. Still not sure if I am supposed to wire the orange to the 0B* slot. Should I try without orange first and see if all works ok, or should I go ahead run the orange to the 0B* ? Thanks for any insight anyone can provide.

Re: Need additional wiring help for nest thermostat, please

Markjosephp — Thu, 20 Oct 2022 21:30:30 GMT

Hi folks,

Chiming in. I'd be happy to take a look into this for you.

I appreciate your help, @Irishjedi.

@ctoles, thanks for posting and letting us know the details of your HVAC system. Based on the wiring diagram from your thermostat, it appears that you have a heat pump type.

You can follow the same wire set up to the Nest thermostat with C (blue), R (red), O/B (orange), W (white), G (green), and Y (yellow). But if you have a Nest Learning Thermostat, move the white wire to the W2/Aux terminal.

Have a look at this article and let us know if you need more help.

Best regards,

Mark

Re: Need additional wiring help for nest thermostat, please

ctoles — Thu, 20 Oct 2022 23:47:06 GMT

Thanks mark Joseph and irishjedi. I wired as outlined above with orange in OB* slot and blue in C slot snd all things seems to be working fine so far. Thanks for all the help.

Re: Need additional wiring help for nest thermostat, please

Markjosephp — Thu, 20 Oct 2022 23:55:18 GMT

Hi ctoles,

Awesome! I'm glad to hear that it's working with the wire set up.

It looks like we have come to a solution so I'm going to be locking this thread in 24 hours unless you have additional questions or concerns.

Best regards,

Mark