I am trying to wire up an Ecobee thermostat to an old (1997) Gas central heating system but I got up into the roof then realised I have no terminal labelled C.

Now, I don't super know what I am doing, but based on the diagram taken from the heater I should in theory be able to tap into the wire on the right side (to the left of the earths) that is labelled 24VAC?

No C terminal enter image description here

1 Answer 1


This line:

enter image description here

is the equivalent of the "C" terminal. Get it from here:

enter image description here

  • Really? Seems counterintuitive to me i thought it would have been the 24vac labelled thing to the left of that. So i have to find the specific wire in the ground section that comes out of the 24v transformer?
    – tomwilson
    Aug 31, 2020 at 0:34
  • After reading some more, this is making more sense to me now :D
    – tomwilson
    Aug 31, 2020 at 0:39
  • 1
    This worked perfectly. Pulled the blue wire from the top centre of the ground section off and created a little extension using some blade connectors and a short section of wire, and tapped the ecobee power extension kit into that.
    – tomwilson
    Sep 5, 2020 at 7:26

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.