I have a Lenox Merit system in the house. I am trying to install Nest E thermostats and want to do it with a C wire. I noticed an unused Blue Wire (pic attached) at the thermostat location and then in the attic saw that the Blue wire is not attached to the C at the circuit board. There is another wire in the C. Do I just add the blue wire in the same location ?



1 Answer 1


Go ahead

The terminal blocks on HVAC control boards can generally handle two wires per terminal, so landing the C wire to your thermostat on the furnace board's C terminal directly is fine.

  • Thank you, thats what I was hoping for. I added the wire straight to the terminal and tested the current thermostats, everything is fine. Now on to the nest
    – rustyocean
    Nov 4, 2018 at 20:24

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.