Nest thermostat incompatible?

[DickDastardly]

 when going through the setup I'm getting the incompatible with the wiring messages. I started deselecting options to see if I could get it to go away. Looks like it's the O and the B being on two different wires that's giving it a hard time?

UPDATE: turns out the O wire wasn't connected to the unit and only the B wire was. Will attach the photo to show.

 

[David_K]

Sometimes both the O and B wires are connected at the thermostat but the wires are not actually attached to anything at the other end on the system control board, so it's worth checking that.

Strictly speaking Nest Thermostats are not directly compatible with systems that need both O and B wires. Those wires control when your heat pump cools or heats your home. It is possible to add a relay to resolve this, usually at a zone control panel, in order to make it compatible but for that, I'd recommend consulting professional help.

Get installation help or HVAC service from a professional - Google Nest Help

[DickDastardly]

I didn't end up posting an update but I was able to figure it all out a couple hours after I posted. It was exactly what you said, the O wire was curled up and the B wire was the only one connected to the unit. I do appreciate your input though and hopefully this thread helps future "professional home owners"

[David_K]

Glad to hear that!