Old gas furnace, no circuit board

[Bret]

Only two wires from furnace to thermostat (white and red). Nest wants more power, like a C wire.

Where does it connect at furnace?

Thanks!

Bret

[Bret]

[kiltguy2112]

You need a c wire adaptor. You can get them at retailors like Home Depot

[Bret]

I’ve ordered one but, looking at the instructions, wonder if finding one location for a C wire might be easier than locating 5 locations for the adapter in a furnace that has no circuit board and no labels on the terminals.

[Bret]

Thanks for the reply.

After receiving the Google C wire adaptor - and not wanting to risk causing a bigger problem by guessing which way to install it - I ordered. 24v transformer.

There is a 120v outlet in the crawl space above where the thermostat wires come through the wall. I attached the transformer wire to the new thermostat (as shown on several YouTube videos), plugged in the transformer, and everything is perfect!

[Jhonleanmel]

Hey Bret, 

Awesome — glad to hear that your issue is fixed. It looks like we can consider this one complete, so I will lock the thread shortly unless I can help out with anything else. 

Thanks for the help, kiltguy2112.

Best, 
Mel