No C stat and heater control board has X, R, B/C, G, W. Good with adapter for R, G and W, but not sure about Y. I’m assuming thru process of elimination, that Y = B/C. But then do I connect both the Y and C wires back up to B/C on board?
B/C is likely to be common with the number of wires coming off of it. I have a feeling that your Y wire does not go to your furnace, and instead goes directly to your outdoor unit. Can you share a picture of your existing thermostat wiring?
What is the brand and model of this air handler/furnace?
Thank you for reply! Attaching thermostat pic (RH, W, Y, G, unused black). Reading a bit more on the community yesterday made me realize that my A/C may be involved. I’ll have to check when I get home, but I believe heater is a Lennox from mid 1980s and is in attic. A/C unit I replaced about a year ago and put on roof. Other posts I read said G becomes C when using adapter. I’m starting to go cross eyed with all these codes, terminals and wires.
Looks like you can use that unused black wire for C and not use the adapter
Well, I see 2 black wires attached to B/C on the furnace, If you’re lucky, one of the black wires goes to the thermostat, and the other black wire goes to the A/C unit. That will mean that you can just connect the wyze without modifying any wiring anywhere else, as follows:
old thermostat new wyze Rh (orange wire) > Rc W (white wire) > W1 Y (yellow wire) > Y1 G (green wire) > G Not connected (black wire) > C
Brilliant, so glad I checked on this community. Much appreciate your time and free advice. Not home at the moment, but will give this a go as soon as get there. Color me pleased.
Hmmm, would not power up. I’m afraid I gave up and put the old thermostat back up. I guess I need to do more research or swallow my pride and call a professional.
Do you have a multimeter? it would be helpful to check between the terminals on that furnace to make sure that there is at least 25VAC between R and B/C
check the voltages between R and the other terminals. do any of them have 25V?
Whichever one has between 25 and 30V should be C.