My ecobee 3 is hooked to a furnace and working nicely (thanks to the many here who helped me find choose it and find the data records etc, ). I have an interesting problem with it though. The furnace and the AC are totally different systems. Different air intakes/ducts, different circuit, different unit, whole AC unit is on a roof and furnace is in the attic about 15 feet away and a few feet down. I fished the Y, G, and R from the AC unit to the ecobee when I installed it (they ran through the attic to where two thermostats used to be so this was not terribly difficult). But I left them unconnected because it’s winter and the AC is mothballed. I connected the W, R, and C to the ecobee from the furnace and that is all that is connected. Ecobee guide says put all the R together. But in this case R is coming from two different 24v transformers, one on each unit. So I’d be pushing 48 volts into it and I don’t think they intended that. What I want to do it hook both AC and furnace into ecobee now and be done with it. But I’m not sure of the best way to go about that. Anyone solved this already?
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