76
OVERHEAT LOCKOUT
77
IGNITION LOCKOUT
Has PCB just been replaced?
If the Boiler is Reset, 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 Flow/Return Differential across the boiler in
excess of 30°C?
Is 215Vdc available at the Gas Valve during
ignition? (* See note)
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 1kW and 10kW?
Check Spark Generator and associated Harness
for continuity, visual condition and position (refer to
Frame 60). Are these functioning correctly?
Check Ignition Electrode and associated Harness
for continuity, visual condition and position (refer to
Frame 58). Are these functioning correctly?
Check Syphon and condensate drain pipework
for blockage and rectify if necessary. Boiler now
working OK?
Reset boiler
No
No
No
No
No
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Reset Boiler
Check the Detection Electrode and associated Harness for
continuity, visual condition and position (refer to Frame 59).
Check if the Condensate Pipe is Blocked.
Fill and vent the system and open all
Isolation Valves, then Reset the Boiler
Check Gas Supply and rectify fault
Check the Flow and Return Thermistors
Check wiring from Gas Valve to PCB and replace if necessary,
otherwise replace the main PCB
Replace the Pump, then Reset the Boiler
Replace Gas Valve
Replace Spark Generator and Harness
as necessary
Replace Ignition Electrode and
associated Harness as necessary
Replace Gas Valve
* Note: due to the wave form of the rectied voltage, the reading will vary depending on the type of meter used to measure
the value. In general terms a reading of greater than 150V indicates that the correct voltage is supplied to the gas
valve
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