I've got an old steam furnace and would like to add a common wire. The wire is already ran, I just have no idea where to connect it.

I thought it would go to TR but that didn't work. Thanks in advance, much appreciated!

Current Wiring Diagram

Picture of the current wires


Found this link here stating that the blue C wire is the 24V AC transformer Neutral wire, hope this is of some use to you.

| improve this answer | |
  • Thank you, that was very useful actually. It helped me figure out the path the C wire takes to complete it's circuit. – Kory Apr 12 '17 at 20:03

After looking more closely I'm thinking the way everything is currently wired it isn't possible to get a complete circuit for the C-wire. I made a proposed diagram that makes a little more sense to me, but I am definitely no expert so I'm looking for advice. Would this work?

enter image description here

I tried to edit the original question but it wouldn't let me post an additional photo.

| improve this answer | |
  • I just tried this and it worked, with one slight modification. The wires RH and W going into the thermostat are reversed in the diagram. the C wire relies on the RH wire to complete the circuit, not W. – Kory Apr 12 '17 at 20:02

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.