I have three wires coming to the existing, very old, thermostat:
- Black, but wired to the "R" terminal of the current thermostat.
- White, but wired to the "W" terminal of the current thermostat.
- Red, but not wired/connected to anything, just wrapped around the other two wires.
I have multi-meter, is there anyway I can make the Ecobee 3 work with this setup?
EDIT in response to ThreePhaseEel in particular.
Folks thanks for the interest in helping me with this.
I thought all I had to do was find the other end of the existing thermostat wires, for the zone I care about. That has not been so easy. See the boiler wiring (see Pictures 2, 3, 4). I can't tell where the end of the thermostat wire for the zone that I'm interested in is. There's a brown wire that I think is typical thermostat wire, but it doesn't have the right wire colors, and originally, I thought it was for the other zone.
I expected that the junction box on the left in Picture 5 would have 120AC as well as two theromstat wires in it, one for each zone, and I would see the red wire there, and I'd just test for continuity. Instead, as seen Picture 6: it has a thermostat wire and a white and black wire. The black and white wires look like power (120VAC) to me based on the gauge.
My goal was to simply to connect the unused red wire to either an obvious common (does that make sense), or buy a 24VAC transformer and attach that to the red wire. But I can't find the end of the red wire (or the other for that matter).
Any thoughts? I thought I was starting to "suss it out", but instead, I'm back to square one. I can't even figure out where my existing thermostat wire is coming into the boiler picture.