L1'-Flow Temp Ov'heat Lockout/No Water Flow Lockout; L2' - Ignition Lockout - Keston System s30 Installation And Servicing Instructions

4.2 'L1' - FLOW TEMPERATURE OVERHEAT LOCKOUT OR NO WATER FLOW LOCKOUT
Is the Boiler and CH System filled with water and all
isolation and radiator valves open?
If the PCB has been replaced check a BCC has been
fitted then restart the boiler.
Is the Flow/Return Differential across the Boiler in
excess of 30°C?
Check the Control/No Water Flow and Return
Thermistors (Refer to Sections 3.12 & 3.25)
RESTART PROCEDURE - To restart boiler, press the "RESTART" button.

4.3 'L2' - IGNITION LOCKOUT

If the boiler is restarted does the
boiler ignite for a short time and
then extinguish?
YES
Check the detection electrode
and associated harness for:
continuity, visual condition and
position (Refer to Section 3.14).
Check if the condensate pipe is
blocked.
Check flue is installed correctly.
Replace as necessary
Check siphon and condensate
drain pipe work for blockage and
rectify if necessary. Boiler now
working OK?
NO
Replace Gas Valve
RESTART PROCEDURE - To restart boiler, press the RESTART button.
Installation and Servicing
SECTION 4 - FAULT FINDING
YES
NO
NO
Is the Gas Pressure available at
the Boiler Inlet (>18 mbar)?
Is 24Vdc supply available at the
Gas Valve?
Unplug gas valve. Is resistance
between outside pins 4KΩ (±2)?
Check spark generator and
associated harness for: continuity
and visual condition. (Refer
to Section 3.15) Are these
functioning correctly?
Check ignition electrode and
YES
associated harness for: continuity,
visual condition and position.
(Refer to Section 3.13) Are these
functioning correctly?
NO
Fill and vent the system and open all
isolation valves, then restart boiler
YES
Check that the Pump is rotating freely. Is
the Differential now below 20°C?
NO
Replace the Pump,
then restart boiler
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
OK, now
restart boiler
Check gas supply and
rectify fault
Check wiring connection
from gas valve to PCB for
continuity. If the wiring is
OK then replace the PCB
Replace Gas Valve
Replace Spark
Generator and harness
as necessary
Replace Ignition
Electrode and
associated harness as
necessary
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