I'm in the midst of replacing the original (by the look of it, 1930's-era) mechanical thermostat with a 44260 programmable digital model from Hunter. Wiring for the original thermostat: R - W - B. The W & B wires control the operation of the furnace, i.e. fire it. The R wire is for a heat anticipator element. The docs for the new thermostat mention nothing about the third wire (this being a "2 wire" system with 3 physical wires, near as I can reason); I'm assuming that this wire can be abandoned / taped off. The wiring diagram on the stack control (vintage Honeywell RA116A) cover indicates no R wire at all when "Series 80" thermostats are used.

So I'm hoping someone out there with more knowledge than I can confirm my deduction is correct :confused:...

Thanks in advance,

Warren

First is the old thermostat 24 volts? Many of those old systems used 120 volts for the control of the system. Check this first and post back. Sometimes trying to mix old tech with new tech can be difficult.