I just moved into a new home and wanted to install a smart Thermostat, upon checking behind my current thermostat I noticed that there was no C- Wire, so I checked the Furnace, and saw a C-Wire, which was bundled up to go to the thermostat. I do not see that wire behind the thermostat though, can I still use an Ecobee extender on the furnace, so I can use the Thermostat?

Updated with pictures

Images https://i.stack.imgur.com/7sjH2.jpg https://i.stack.imgur.com/8MjFN.jpg

  • 1
    So, there's a wire attached to the C connector on the furnace, and that wire is part of the cable that goes to the thermostat? It's other end is up there somewhere. But if you can't get to it, just pretend that it doesn't exist. Nov 24, 2021 at 14:46
  • Either there's a junction somewhere that the wire is not continued through, or the wire is there but folded back into the wall.
    – Ecnerwal
    Nov 24, 2021 at 16:14
  • Can you post photos of the wiring at both ends please? Nov 25, 2021 at 1:16
  • Just updated with the pictures
    – Karen
    Nov 25, 2021 at 4:14
  • Now that you have a picture of the connections at the thermostat, you can turn off the power to the furnace and remove the mounting plate from the wall and see if the fifth wire is hiding behind it. Nov 25, 2021 at 15:04


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