topic Re: Tc and To wires in Nest Thermostats

Tc and To wires

kweb33bsu — Tue, 03 Jan 2023 14:37:11 GMT

My current Lennox thermostat has wires labelled Tc and To. From looking on their website the Tc wire is a common sensor terminal and the To wire is an outdoor or discharge air temperature sensor. When I go through the Nest setup - it looks like I'm incompatible. Is that the case? Seems odd given this system is only 3 years old.

Re: Tc and To wires

Jhonleanmel — Fri, 06 Jan 2023 18:45:03 GMT

Hi kweb33bsu,

Thanks for posting.

Your wire label indicates an incompatible system.

These systems usually only work with thermostats made by the same manufacturer. But some incompatible systems may also have the option to use standard heating system wires. Contact a local pro and have them check if your system can be rewired to be Nest compatible.

Best,
Mel

Re: Tc and To wires

Jhonleanmel — Mon, 09 Jan 2023 19:42:37 GMT

Hey there kweb33bsu,

Checking back in should you still have some questions here. Let us know by replying to this thread.

Best,
Mel

Re: Tc and To wires

kweb33bsu — Tue, 10 Jan 2023 16:21:29 GMT

Thanks! All is well. I contacted a professional and it wasn't a problem. Those two wires are temperature sensors and they are not necessary.

Re: Tc and To wires

Jake — Tue, 10 Jan 2023 20:18:27 GMT

Hey there,

I am glad to hear you were able to get help, and everything is good to go from here. I am going to go ahead and keep the thread open for 24 hours in case you have any questions from here.

Best regards,

Jake