Google Nest Thermostat not recognizing W wire

[TJD]

I have an older gas furnace, heat-only, with a 2-wire thermostat to an old Honeywell mercury switch.  Wire colors are not to code, but work in any configuration with the old Honeywell thermostat.

I have a Nest generation 1 thermostat.  I installed it with a 24V power supply.  All good with power (no error messages).  I installed on e of the old thermostat wires into the nest.  No W wire detected.  I tried it with the other thermostat wire.  No W wire detected.  Wires are clean and straight.  When inserted into the nest wire holes, paddles stay down (confirming wire is in place)

The thermostat wires work.  I can short them manually to call for heat successfully.  I can hook them up to the old Honeywell switch and they work.  Voltage through the old wires is 24V.

Any suggestions?

[MelbaDT]

Hi TJD, 

Sorry for the delayed response but thanks for reaching out to the Google Nest Community. 

Do you still need help with this? If yes, could you provide a photo of the Honeywell thermostat wires as well as your Nest thermostat one? I want to be able to compare both so we can work from there. 

Best, 

Melba

[TJD]

Thanks for replying.....unfortunately I am not at the house and will not be there until the end of March to take pictures.  Can I reach out to you with pictures then?

Thanks, TJ

[Ryan_G]

Hey folks,

Thanks for visiting the Google Nest Community. 

Since this thread hasn't had activity in a while, we're going to close it to keep content fresh.

If you have additional questions, feel free to submit another post and provide as many details as possible so that others can lend a hand. 

Hope this helps!

Kind regards,

Ryan