Old Honeywell Thermostat 3 wire set up not compatible

[larry_ibalio2000]

Hello… pls help. I can’t install my Wyze thermostat because I only have red white and green wires on my old Honeywell thermostat. I live in Canada so don’t have AC… attached is a picture

[speadie]

Do you have a picture of the heating device?( furnace/ boiler)

[larry_ibalio2000]

Thanks Speadie… was reading some of your old posts but just want to make sure… here’s the photo of my furnace…

[speadie]

You have the furnace board control the heating fan, and not the thermostat.
Then you would have a spare green wire that can be connected to C instead of G on both ends.
You would lose the ability to control the fan manually or through the thermostat though.

Otherwise you would need to run a new wire.

[larry_ibalio2000]

Ok, right now the fan is automatically activated by the thermostat depending on the temperature setting… I guess the safest is run a separate wire

[larry_ibalio2000]

Thanks Speadie, one more thing… where do I put the C wire on the Furnace’s board?

[speadie]

C wire goes on the C terminal.
For your furnace that’s the rightmost terminal.