Ecobee Smart Si Installation Manual page 24

Boiler
R
C
W
Smart Si Thermostat
* Remove RH/RC factory jumper
C terminal to be connected to heating
transformer common
W2 W
Y2 C RH RC G
AUX O/B
Single stage boiler with air handler, dual stage cool
Air Handler
Y1
Y2
R
C
G
Y N/C
2-stage AC
Y1
Y2
R
C
19