topic Re: Nest Reverse Heating and Cooling - No O/B Wire for heat pump in Nest Thermostats

Nest Reverse Heating and Cooling - No O/B Wire for heat pump

ohmyjosh — Fri, 03 Mar 2023 20:18:45 GMT

Hi,

I recently installed a nest 3rd gen to replace a Honeywell FocusPRO TH6110D. I wired it correctly, double triple and quadrupled checked. (see Photos) When I went to test it the HEAT blows cold (coldish) air and COOL blows warm air. I know there is something to do with the changing O/B in the settings but there wasn't a o/b wire attached to the old Honeywell. (again see photos) Because the nest is "smart" it wont let me adjust or look at any Heat Pump settings to change from O to B because a wire isn't connected.

I re-attached my old Honeywell and it works just fine without the o/b wire, it seems like the W wire serves as both the w and O/B on that system.

In any case I was hoping someone might be able to help. Namely @Patrick_Caezza since he seems to have all the right answers. 🙂

Photos - https://imgur.com/a/rEJoHTa

Other note: There are unused, unstripped wires still in the wall orange and black. (which orange traditionally is the O/B right?)

Re: Nest Reverse Heating and Cooling - No O/B Wire for heat pump

Patrick_Caezza — Fri, 03 Mar 2023 22:04:05 GMT

Move the white wire from the W1 terminal to the OB terminal. Then reset the thermostat to factory default and set it up again.

The Y wire is what turns the heat/cooling on and off. The O/B wire is what selects heating or cooling.

Re: Nest Reverse Heating and Cooling - No O/B Wire for heat pump

ohmyjosh — Fri, 03 Mar 2023 22:31:45 GMT

Thank you so much! Totally worked. You are a Gem. Have Venmo?

Re: Nest Reverse Heating and Cooling - No O/B Wire for heat pump

Patrick_Caezza — Sat, 04 Mar 2023 01:57:15 GMT

Thanks, I do this to help people

Re: Nest Reverse Heating and Cooling - No O/B Wire for heat pump

Markjosephp — Thu, 09 Mar 2023 21:56:06 GMT

Hello folks,

Thanks for your expertise here, @Patrick_Caezza. Big help!

@ohmyjosh, I wanted to follow up and ensure you are good to go. I appreciate you posting and updating us on your efforts to address your concern and find a fix. So I will lock the thread within 24 hours unless I can help out with anything else.

Regards,

Mark