I just bought a Wyze thermostat to replace an old one at the current place I live. The furnace is close by to the thermostat but it’s heat only using R, W, and G wires - there’s no C wire. I have found that there are extra wires at the thermostat and furnace end, attempted to connect the spare blue wire to the COM/24v terminal at the furnace and then connect that to the C spot on the thermostat. When I power on the furnace, the Wyze thermostat does not power on and just makes a clicking sound. I have used a multimeter and the R-G and R-W wires are getting ~28V but R-C is only getting about ~17-18V. Any help would be appreciated
Furnace is model 59TN6A060V171114 - Carrier 2 stage ECM
Seems to be a condensate pump spliced to the furnace wires. The red and blue wires coming from the pump to the furnace are attached like this:
Pumps red wire connects to R at furnace terminal
Pumps blue wire spliced to thermostat R
Might just be the image, but it looks like the wire jacket at the thermostat is grey and the wire jacket at the furnace is brown, this leads me to think that the wire might be spliced somewhere and that the blue wire is not well connected. try a different wire maybe, or check the wire leading from the furnace to see if you can find a splice point.
Good call, they are different colors. I have actually tried the black wire and blue wire and neither worked. I will see if I can find a splice point but the brown jacket wires go behind the furnace into the wall so not sure if I’ll be able to find it. If I can’t find it, any other options?
Actually, upon further inspection it’s the same jacket, it just had a white coating over it. I’ll try all of the other wires though and see if any of them work.
Ok I’ve tried every other wire and all the same result; Wyze stat doesn’t power on, makes a clicking sound, and I get ~17 volts on R + other wire for C. Can I use the C adapter with just RWG?
No real point in using the C adapter on a non-air conditioned system, but if you were willing to lose independent fan control, you could use the Green wire as C. just disconnect it from G on both sides and connect it to C instead. the furnace should kick on the fan by itself when there is a call for heat.
Ok I just tried that and same thing is happening, except now the Wyze stat is clicking much quicker. Before it was making a clicking sound every 3-5 seconds, now it’s clicking every second.
Probably an under powered transformer then.
You can either upgrade the transformer on the furnace or get a plug in C adapter transformer to run the thermostat off of. The wyze’s included c adapter relies on the furnace’s transformer, so that won’t help you.
Ah ok, that’s unfortunate. It’s not my house so I’ll probably just return the Wyze thermostat and keep living with the old thermostat. Thanks for trying though speadie
