I need to hook up a C wire to power a wi-Fi thermostat. I have an extra unused blue wire, but I don't know what to hook it up to at the furnace. I don't have the traditional wiring R W RC G Y C on the furnace. I did locate a 24V transformer coming out, but I'm not sure if I can hook the blue wire (C) to the red hot wire which is already carrying a red wire to the thermostat RH terminal.
Best Answer
The gray (grey) wire coming off the transformer is the
Cwire. You can make your connection down near the transformer, or up where the A/C condensing unit wiring connects.