Okay, I’m trying to replace a 34-year-old thermostat with a new Ecobee 3, and the wiring doesn’t quite line up with the instructions.
The existing thermostat is a Trane Weathertron with a Baystat 239 board.
It’s a heat pump system, and some amount of research has already gotten me a long way toward knowing what to do.
Below are the wires I have, and what research tells me they correspond to. I’m going to use the format that someone on another forum used: Current label - wire color - expected destination.
X2 - Blue - W2
O - Red - O/B
G - Green - G
Y - Yellow - Y1
W - White - W1
B - Blue - C
F - White - ???
As can be seen, the mystery is this F wire. Anyone have an idea what that’s for? Where I should plug it in on my Ecobee? Remaining options are Y2, Rh, or PEK. Or it could wind up spliced to another wire or it could be taped off and unused.
Any help is appreciated!