ICM Controls SC 2311 Installation, Operation & Application Manual page 20

SimpleComfort
24 VAC, return
V-VR
24 VAC, common
X
Reversing valve (cooling mode)
R
Compressor contactor
M
2nd stage heating circuit (sequencer 1)
Y
Fan contactor circuit
F
Emergency heating circuit
E

2311 Electronic Thermostat Conversion to:
®
Lennox HP19 and HP20 Heat Pump Systems
SC 231 1
Electronic Thermostat
W1
R C Y W2
O/B
E G