Baxi 124 Combi Installation And Service Manual page 51

I
CH system pressure less than
0.5 bar or greater than 2.7 bar
NO
J
Ensure that the boiler and system
are fully vented
YES
K
Is there 230V at:
1.
PCB - X13 connector terminals between:-
Blue & Black (central heating mode)
Blue & Brown (domestic hot water mode)
see Wiring Diagram
YES
Check diverter valve motor cable
2.
Diverter valve motor
L
Is mains water filter & assembly
clean, and rotor moving freely ?
NO
Clean or replace
M
1.
Temperature sensors faulty.
Cold resistance approximately
10kΩ @ 25° C (CH sensor)
20kΩ @ 25° C (Flue sensor)
(resistance reduces with increase in temp.)
2.
If pump is running the heat exchanger could be
obstructed
© Baxi Heating UK Ltd 2017
YES
Restore system pressure
Check wiring and PCB - X22
connector for approx. 5V DC
between green & black - see
Wiring Diagram
NO
Check flow temperature sensor connections
and position.
Cold resistance approximately
10kΩ @ 25° C (CH sensors)
(resistance reduces with increase in temp.)
YES
NO
YES
Replace diverter valve motor
Check wiring and PCB - X22
YES
connector for approx. 5V DC
between red & blue from Hall
effect sensor - see Wiring Diagram
NO
YES
17.0 Fault Finding
YES
Replace hydraulic pressure sensor
NO
Replace PCB
System fault - correct
NO
Go to section 'B'
Replace PCB
NO
Replace PCB
Replace sensor
Replace heat exchanger
Replace sensor
YES
Replace Hall Effect Sensor
51