Hi.. i wired my new Aprilaire humidifier exactly as directed to an older Lennox furnace. The furnace now turns on, no matter what the thermostat setting.
It has something to do with the "C" connection: if I remove the "C" wire from the Aprilaire control (which is connected to "C" on furnace), no problem. As soon as i connect the "C" wire back, furnace turns on--even if thermostat is set to "system off".
I double-checked it all. Humidifier runs as per Test cycle. I installed Aprilaire humidifiers in the past no problem. What is going on?!???
Thank you, Dan