ICM Controls SC 2811 Installation, Operation & Application Manual page 14

SimpleComfort
Note 1: W2 terminal on PCB capped
Note 2: X terminal on PCB capped
24 VAC, return
R
24 VAC, common
C
Reversing valve (cooling mode)
O
Compressor contactor
Y
2nd stage heating circuit
W1
Fan contactor circuit
G
Outdoor thermostat
W2
Defrost sensor
X

2811 Electronic Thermostat Conversion to:
®
ComfortMaker CYC Series Heat Pump Systems
SC 281 1
Electronic Thermostat
W1
R C Y1 W2 Y2
O/B
(capped)
(capped)
G W3