2

My HVAC control board has two bundles of wires. One has 5 wires which runs to the thermostat but the 5th wire which I want to use as C is currently unused. The second set runs to the unit outside (condenser?).

My vague understanding is that I could just plug the unused blue wire into C beside the existing white wire and use it as C.

Here's some picture

enter image description hereenter image description here

2

You're spot on

Hooking the existing blue wire up to the C terminal alongside the white wire that's already there will do what you want and get you that C wire for your Ecobee.

  • Thanks for the quick reply. Do you think you could explain a bit why doing this won't interfere with the existing condenser wiring? – Fletcher Moore Jul 26 '17 at 0:01
  • @FletcherMoore -- look at your Y terminal and how it's double tapped already – ThreePhaseEel Jul 26 '17 at 0:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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