Appendices 91
12.3 Ladder Diagram
LIVE
NEUTRAL
240 VAC
Relay 1
Relay 2
Igniter
Circulation Pump
Speed Control
Transformer
Primary
Secondary
MCU 1
MCU 2
Flame rod
WD-RSS
DC24V
Relay 1
Relay 3
Driving Circuit
Flow Sensor
WPS
DC12V
Fan
Hall Sensor
BLDC-FAN
Water Adjustment
Valve
Flow Control
DC15V
Vent
Separation
Detector
Supply
Thermistor
Outlet
Thermistor 1
Return
Thermistor
UART
Communication
Interface
FRONT
PANEL
Communication
Interface
FU
S
E
Inlet
Thermistor 1
EMI
FILTER
PWM
NCB500/700 Combi
Series Only
DC 5V
Flow Control
3WAY
Relay 3
AC130
Trans
V
Relay 2
Exhaust
Thermistor
HTL switch
Buner
Outlet
Thermistor 2
ROOM Controller
DC 9V
HTL switch
Heat Exchanger
GAS V/V1
DC30V
Mixing
Valve
Outdoor
Thermistor
Low water
Pressure switch