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FAULT 2
Central Heating Pressure below 0.7 bar.
5 seconds - 1 sec - 1 sec - 5 seconds
If the pressure in the heating circuit falls below 0.7 bar the low pressure switch contacts
open and the boiler is totally disabled until the pressure is increased, or the faulty
switch replaced.
POSSIBLE CAUSES
Low pressure in the heating circuit
Faulty Low Pressure Switch
FAULT 3
High Limit Thermostat Failure.
5 seconds – 1 sec - 1 sec – 1 sec - 5 seconds
The high limit thermostat provides a mechanical form of high temperature protection if the
electronic system fails (Thermistor). The high limit stat becomes open circuit at 102° and
fault 3 will be displayed.
The thermostat will automatically reset as temperature reduces, but manual reset of the
boiler will be required at the control panel.
POSSIBLE CAUSES
Central heating thermistor faulty or not attached to pipe work
Primary heat exchanger needs venting (loosen automatic air vent cap)
Faulty high limit thermostat
Faulty Connections at PCB
FAULT 4
Printed Circuit Board Failure
5 seconds - 1 sec - 1 sec - 1 sec - 1 sec - 5 seconds
The PCB incorporates a pre-programmed chip which contains the software essential for
the safe operation of the boiler. The chip is responsible for ensuring the timing sequences
for the gas valve, and that the fan and pump run at the correct times. Also the chip
contains data to ensure that temperature values do not exceed design specifications, and
is in effect the brain of the boiler. NO attempt should be made to replace the chip. Only a
replacement PCB should be used to rectify the fault.
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