Nest E-thermostat wiring compatability

[perry637]

How to wire nest E-thermostat with this existing configuration. ? I'm in US midwest with gas furnace (Lennox) and separate A/CHow to wire nest E-thermostat with this existing configuration. ? I'm in US midwest with gas furnace (Lennox) and separate A/C

[David_K]

The online Compatibility Checker has full instructions on how to check if your heating and cooling systems are compatible with Nest thermostats. You can also find additional information here:

Nest thermostat compatibility - Google Nest Help

[perry637]

Thx David, of course i did try the checker before posting. It came back as not-compatible. Would like to know why since its a very typical install. I suspect existing wiring may be wrong (but it works)..

[EdwardT]

Hi perry637,

Thanks for reaching out. Based on the current wiring, it looks like it would work with the Nest Thermostat. Nest thermostats are designed to use very little power, and in many cases they can use your system’s heating and cooling wires to get enough consistent power. But sometimes, you may need to connect a common wire (C wire) or power accessory, like the Nest Power Connector, to make your system compatible.

Thanks,

Edward

[perry637]

Hi EdwardT - thank you for your reply. I see 6 wires coming into this thermostat (see original pic), can one of these be used to power? I see there is an R as well as RC connection, can the RC be used as a C-wire itself?

Thank you,

Jim

[EdwardT]

Hi perry637,

Thanks for the response. To make sure that we'll be wiring the Nest Thermostat correctly, please check the control board of your HVAC so we can see where the other ends of the wires are connected to.

Thanks,

Edward

[Jhonleanmel]

Hi folks,

Chiming in to see if you still need assistance with this. Let us know if you have additional questions ― we'd love to help.

Best,
Mel

[Jhonleanmel]

Hi everyone,

Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.

Thanks,
Mel