Bosch Worcester 15SBi Installation And Servicing Instructions page 11

Fig.13 . Wiring diagram - pictorial.
Cylinder
Thermostat
bl - Blue
br - Brown
y - Yellow
g - Green
CH Sensor
Flame
Sense
Electrode
Pump
1 1 1
X10 X11 X12
Control Board
X3
1
X1 X2
br bl
2 orange
Fan
Spark
Electrode
Mid
Position
Valve
Y Plan
(Optional)
X4
br
X5
br
X6
br
bl
bl
y
2 red
11
Overheat
Cut-off
Gas Valve
Air Flow
Switch
2 green
Facia
Mounted
Timer
(Optional)