68
OVERHEAT LOCKOUT
Are the Boiler and CH/DHW system
lled with water and are all Isolation
Valves and Radiator Valves open?
Fill and vent the system and open
all Isolation Valves, then Reset the
Boiler
no
yes
Is the Flow/Return Differential across
the boiler in excess of 35°C?
Check the Flow and Return
Thermistors (refer to frame 74)
no
yes
Check that the Pump is rotating
freely. Is the Differential now below
20°C?
Replace the Pump, then Reset
the Boiler
no
Reset boiler
69
IGNITION LOCKOUT
If the boiler is reset, does it ignite for a
short time and then extinguish?
Check the detection electrode and associated harness
for continuity, visual condition and position (refer to
Frame 46). Check if the condensate pipe is blocked.
yes
no
Is the gas pressure available at the boiler > 18mbar?
Check gas supply and rectify fault
no
yes
Is 230Vac available at the Gas Valve?
Check wiring from Gas Valve to PCB
and replace if necessary, otherwise
replace the main PCB
no
yes
Unplug the Gas Valve, is the resistance between the
outside pins between 1kΩ and 10kΩ?
Replace Gas Valve
no
yes
Check Spark Generator and associated Harness for
continuity, visual condition and position (refer to Frame
??). Are these functioning correctly?
Replace Spark Generator and
Harness as necessary
no
yes
Replace Ignition Electrode and
associated Harness as necessary
no
Check Ignition Electrode and associated Harness for
continuity, visual condition and position (refer to Frame
??). Are these functioning correctly?
yes
Replace Gas Valve
yes
70
FALSE FLAME LOCKOUT
Check routing and integrity of internal boiler
wiring is OK. Check condition of Flame
Sense Electrode and replace if deteriorated.
yes
Reset the boiler, does boiler work OK?
no
Replace Flame Detection Electrode
Check routing and integrity of internal boiler wiring
yes
no
Disconnect the electrical connection to the Flame
Sense Electrode. Is there continuity between the
Electrode and earth?
50
- Installation & Servicing
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