I recently upgraded my thermostat to a Honeywell RTH7500D. My furnace is a Lennox G50UH. I only have two wires attached to my thermostat: W and R. Everything works fine, but am I missing out on some functionality or efficiency with only these two connections? Thanks.
Missing the ability to turn on the blower independantly. Other then that it's a single stage furnce so it's either on or off. Run another wire from the thermostat G terminal to the furnace G terminal if you want the on/auto fan function to work.