65
Displayed fault
code
System characteristics Cause Measures
373 Burner in a fault state Heat transfer too low dur-
ing calibration
Temperature limiter has
shut down.
■
Ensure adequate heat transfer.
■
Check circulation pump for faults,
scale or blockages.
■
Check function of 3-way diverter
valve. Vent the system.
■
Check function of flow sensor.
Reset the appliance.
374 Burner restarts Preparation for ionisation
current calibration: Stabili-
sation conditions for pre-
calibration not met.
■
Check ionisation electrode and
connecting cable.
■
Check plug-in connections for
loose contacts. Check the flue
system. Remove flue gas recir-
culation if necessary.
■
Check system for condensate
backup. Visually check gas sole-
noid valve inlet and inlet strainer
for contamination.
Note
To prevent water damage, de-
tach fan unit before removing the
burner.
Deposits on the electrodes indi-
cate foreign bodies in the com-
bustion air. Check the installation
room and flue system for causes
of the deposits. For example:
Laundry detergents, cleaning
agents, toiletries, deposits in the
ventilation air supply (chimney).
If burner gauze assembly and
ionisation electrode have been
replaced, also clean fan unit,
gas/air channel and Venturi ex-
tension.
Reset the appliance.
Troubleshooting
Fault messages (cont.)
6179762
Diagnosis
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