How do I create a C wire?

Question

My furnace is old and only has 4 wire connections, but I require a C wire. How can I create one based on this diagram?

I do have 5 wires running between the furnace and thermostat. enter image description here

score 1 · Answer 1 · answered Dec 05 '18 at 14:11

1

The way to find a C wire is to look for the transformer, and then find the secondary (low voltage) wire that is not the R wire.

In your case, this is the wire in the diagram going to the right of the part labeled "24 VAC", which is the transformer.

answered Dec 05 '18 at 14:11

longneck

1 Answers1