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Diagram 9.1
9 Fault Finding
NEON
INDICATORS
Neon Indicators - An Aid to Fault Finding
THE NEON INDICATORS ARE AN AID TO FAULT FINDING ONLY. FAILURE OF ANY OF THE NEON INDICATORS DOES NOT WARRANT THE
REPLACEMENT OF AN OTHERWISE SATISFACTORY PRINTED CIRCUIT BOARD (PCB).
Fault with mains supply or PCB fuse
Ignition, pilot or flame proving fault -
see detailed fault finding chart.
Air flow proving fault - that is fan or air
pressure switch - see detailed fault finding
chart.
NO
NO
NO
Overheat cut off device tripped or
thermostat, overheat cut off device faulty
- see detailed fault finding chart.
Is neon 2 lit?
Is neon 4 lit?
System satisfactory
Is neon 3 lit?
Is main burner operating?
Is neon 1 lit?
NO
NO
YES
YES
YES
YES
YES
Multi-functional control/harness problem
- see detailed fault finding chart.
4120
9.1 Electrical
IMPORTANT:
On completion of the Service/Fault Finding task
which has required the breaking and remaking of the electrical
connections the earth continuity, polarity, short circuit and
resistance to earth checks must be repeated using a suitable
multimeter.
Refer to neon indicators “An Aid to Fault Finding” diagram 9.1,
Boiler Fault Finding diagram 9.2, Pump Overrun Fault Finding
diagram 9.3 the Functional Flow diagram 9.4, Gravity Domestic
Hot Water and Fully Pumped Central Heating, diagram 9.5,
Fully Pumped Open Vented or Sealed Water System, the
Pictorial Wiring diagram 9.6, Gravity Domestic Hot Water and
Fully Pumped Central Heating and diagram 9.7 Fully Pumped
Open Vented or Sealed Water System.
9.2 Electrical Supply Failure
Failure of the electrical supply will cause the burner to go out.
Operation will normally resume on the restoration of the electrical
supply. If the burner does not relight after an electrical supply
failure the overheat device may need resetting.
Remove the control cover, see diagram 6.6 and push the reset
button on the front of the control box, see diagram 6.1.
If the cutoff operates at any other time press the reset button and
the burner should relight.
If the fault persists refer to fault finding chart.
NOTE:
the pump may run for several minutes when power is
first applied, regardless of a call for heat.
