At the thermostat, I have the following:
connector label (wire color)
R (red)
G (green)
Y1 (yellow)
W2 (white)
W1 (red)
Y2 (none)
C (blue)
With the faceplate off, I measured the following voltages:
R-G 27.8 vac
R-Y1 28.2 vac
R-W2 28 vac
R-W1 28.2 vac
R-Y2 2 vac
R-C 28 vac...