Upgrading a Honeywell Thermostat T6169B Line Voltage to Ecobee3 Smart Thermostat

[Thermostat]

You will need a 120vac to 24vac transformer and two relays for each FCU. I am out of town for the holidays. I will try to put together a wiring diagram and upload it by the end of the weekend

[Thermostat]

I have attached a wiring diagram for your system. I am not sure how your OFF HI MED LOW switch is wired in so I have have shown it as it would typically be wired in.