49
Installation and Servicing
Section 4 - Fault Finding
FAUL
T FINDING
4.3 ‘L 02’ - IGNITION LOCKOUT
Refer to Section
3.11
&
3.23
Is the Boiler and CH System filled with water and all
isolation, system filter and radiator valves open?
YES
Fill and vent the system and open all
isolation valves, then restart boiler
Is the Flow/Return Differential across the Boiler in
excess of 30°C?
NO
Check that the Pump is rotating freely.
Is the Differential now below 20°C?
YES
NO
Replace the Pump,
then restart boiler
NO
OK, now restart
boiler
YES
Check the Flow and Return Thermistors
Check resistance using a suitable multimeter
connected across the thermistor’s terminal pins
Temperature
Resistance kΩ
25
o
C
9.7 – 10.3
60
o
C
2.4 – 2.6
85
o
C
1.0 – 1.1
4.2 ‘L 01’ - OVERHEAT LOCKOUT
If the boiler is restarted does the
boiler ignite for a short time and
then extinguish?
YES
Is the Gas Pressure available at
the Boiler Inlet (>18 mbar)?
Check the electrode and
associated harness for:
continuity, visual condition and
position.
Check if the condensate pipe is
blocked.
Replace as necessary
NO
Check gas supply and
rectify fault
NO
YES
Is approx 24Vdc supply available at
the Gas Valve?
YES
Check spark generator and
associated harness for: continuity
and visual condition.
Are these functioning correctly?
YES
Check electrode and associated
harness for: continuity, visual
condition and position.
Are these functioning correctly?
Check trap and condensate drain
pipe work for blockage and rectify
if necessary. Boiler now working
OK?
Check wiring connection
from gas valve to
PCB for continuity. If
the wiring is OK then
replace the PCB
NO
Replace Spark
Generator and harness
as necessary
NO
Replace Electrode and
associated harness as
necessary
NO
Replace Gas Valve
NO
Unplug gas valve. Is resistance
between outside pins between
4k
Ω
(± 2)?
YES
Replace Gas Valve
NO
YES
Refer to Section
3.9
Refer to Section
3.9
Refer to Section
3.14