Error code
Description
Return temperature too high:
Bad connection: check the wiring
Faulty sensor: replace the sensor if necessary
Sensor not connected or incorrectly connected:
Check that the sensors are operating correctly
Check that the sensor has been fitted properly
No circulation:
Vent the air from the CH system
Check the circulation (direction, pump, valves)
Check the water pressure
Check the cleanliness of the heat exchanger
If present: check the boiler type parameter setting
Difference between the flow and return temperatures too great:
No circulation:
Vent the air from the CH system
Check the circulation (direction, pump, valves)
Check the water pressure
Check the cleanliness of the heat exchanger
Check that the heating pump is operating correctly
If present: check the boiler type parameter setting
Sensor not connected or incorrectly connected:
Check that the sensors are operating correctly
Check that the sensor has been fitted properly
Faulty sensor: replace the sensor if necessary
Temperature of heat exchanger above normal range (STB high-limit thermostat):
Bad connection: check the wiring
Sensor not connected or incorrectly connected:
Check that the sensors are operating correctly
Check that the sensor has been fitted properly
Faulty sensor: replace the sensor if necessary
No circulation:
Vent the air from the CH system
Check the circulation (direction, pump, valves)
Check the water pressure
Check the cleanliness of the heat exchanger
If present: check the boiler type parameter setting
If present: Air pressure differential switch has been triggered:
Air supply or flue gas outlet blocked: check air supply and flue gas outlet for blockage
Five failed burner starts:
No ignition spark:
Check cabling of ignition transformer
Check the ionisation/ignition electrode
Check breakdown to earth
Check the condition of the burner cover
Check the earthing
Defective control SU PCB
Ignition spark but no flame:
Vent the gas supply to remove air
Check that the gas valve is fully opened
Check the gas supply pressure
Check the operation and setting of the gas valve unit
Check that the air supply inlet and flue gas outlet are not blocked
Check the wiring on the gas valve unit
Defective control SU PCB
Flame present, but ionisation has failed or is inadequate:
Check that the gas valve is fully opened
Check the gas supply pressure
Check the ionisation/ignition electrode
Check the earthing
Check the wiring on the ionisation/ignition electrode
11 Troubleshooting
123157 - v.12 - 07022018
73
