I have a 25+ year old York Forced Air electric furnace, want to hook up the new Honeywell WIFI stat, there is no C wire connection in the Furnace itself, and some instructions have indicated using the B terminal - which has the 24V wire from the Transformer connected to it. The confusing part of the Furnace wiring diagram shows that the R terminal is also connected to the secondary side of the transformer to what looks like the Common wire, and here's where it's confusing me, that wire is going to Ground as well? So can the B terminal be used as the C wire to the stat? Here's the wiring diagram. There's no AC or Heat Pump, purely used for heating.

York Furnace Wiring Diagram

  • Model Number: N2AHD10A06HNA – Dave E. Feb 7 '16 at 14:05
  • 3
    Isn't this a mega-duplicate by now? – keshlam Mar 8 '16 at 22:36

Based on the schematic, the B terminal should be able to be used as a C. Simply extend a wire from B, and connect the C terminal of the thermostat to it. It should look something like this...

enter image description here

Though since you said you don't have A/C hooked up, you won't have the Y wire connected.

  • nice overlay onto the schematic – Tim B Apr 8 '16 at 14:45

It's a common thing on the older electric furnaces, just use a good voltmeter and check the reading between R and B if you get 24 volts, then B is actually the C terminal you are looking for or Common as the C indicates. I had this issue installing one of the new Micro electronic thermostats on a rooftop unit and needed an extra wire to install this thermostat. Thanfully whoever installed it ran extra wires.

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