I've been replacing my thermostats with the RadioThermostat CT50, which reports to my home-brew home control/alarm system. I have a 3-year old AireEase 4-ton unit in the shop that has a Comfort Sync 103796-03 smart wifi thermostat. When I removed it, there are only four connected wires, two of which go to terminals marked I+ and I-.
I googled this and found that this is some kind of communications bus architecture that sends heat/cool/fan signals over just the two wires.
The guy that installed it says 'you should be able to convert it fairly easily', but I am sort of stonewalled here. I have plenty of unused wires in the thermostat cable. I was thinking I may have to change out logic or comm boards in both the heat pump and the furnace. Has anyone done this successfully?
Easiest course is to just put the ComfortSync back, admit defeat, and have one 'bastard' thermostat. But I would REALLY hate to do this unless there is lots of $$$ involved.
The upper photo is the air handler, lower is the heat pump. Could this be simply a matter of installing the thermostat and connecting the W1,W2,Y,G,R leads to the terminal strips in the photos?