4.2 OVERHEAT LOCKOUT
4.3 IGNITION LOCKOUT
If the boiler is restarted, does it ignite for a short
time and then extinguish
Are the boiler and ch/cylinder system lled with water
and are all isolation valves and radiator valves open?
Is the gas pressure available at the boiler > 18mBar?
Is the ow/return differential across the boiler in
excess of 30°C?
Is 24Vdc available at the gas valve during ignition?
Check that the pump is rotating freely. Is the
differential now below 20°C?
Unplug the gas valve, is the resistance between the
pins between 1kΩ and 10kΩ?
Check spark generator and associated harness for
continuity, visual condition and position (refer to
Section 3.17). Are these functioning correctly?
Check ignition electrode and associated harness
for continuity, visual condition and position (refer to
Section 3.15). Are these functioning correctly?
Check siphon and condensate drain pipework
for blockage and rectify if necessary. Boiler now
working OK?
Restart boiler
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Check the detection electrode and associated harness
for continuity, visual condition and position. Check if the
condensate pipe is blocked.
Fill and vent the system and open all
isolation valves, then restart the boiler
Check gas supply and rectify fault
Check the ow and return thermistors
Check wiring from gas valve to PCB and replace if necessary,
otherwise replace the main PCB
Replace the pump, then restart the boiler
Replace gas valve
Replace spark generator and harness as
necessary
Replace ignition electrode and
associated harness as necessary
Replace gas valve
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