2wire Thermostat Diagram. March 18 2018 by. In the honeywell t87f thermostat series the single pole double throw switch makes closes one set of contacts when the temperature falls to turn on the heating appliance.
Installing the wrong thermostat type always install a thermostat to its compatible base. Turn off the power to your hvac system remove the existing thermostat and mark the wires. Room thermostat wiring diagram wiring a thermostat with 3 wires pertaining to 3 wire room thermostat wiring diagram image size 800 x 600 px image source.
The red wire has to be connected to the r terminal of the furnace thermostat and similarly.
Remove the control panel of the old furnace thermostat. The procedure to install the nest thermostat with 2 wires is the same for both thermostats. How to wire a thermostat. The extra expense isnt excessive though.