Viessmann VITODENS 222-F Installation And Service Instructions Manual page 79

Fault messages
(cont.)
Fault number System characteristics
on the display
F.372 Burner in a fault state
F.373 Burner in a fault state
Cause
Repeated flame loss dur-
ing calibration
Heat transfer too low dur-
ing calibration
Temperature limiter has
shut down.
Troubleshooting
Measures
Check ionisation electrode and
connecting cable. Check the plug-
in connections.
Check flue system; remove flue
gas recirculation if required.
Check system for condensate
backup.
Visually inspect gas train inlet and
strainer on the inlet side for con-
tamination.
Note
To prevent water damage, detach
fan unit before removing the burn-
er.
Note
Deposits on the electrodes indicate
foreign bodies in the combustion
air. Check the installation room and
flue system for causes of the de-
posits. For example: Laundry de-
tergents, cleaning agents, toilet-
ries, deposits in the ventilation air
supply (chimney).
If burner gauze assembly and ioni-
sation electrode have been re-
placed, also clean fan unit, gas/air
channel and Venturi extension.
Reset the appliance.
Ensure adequate heat transfer.
Check circulation pump for faults,
scale or blockages.
Reset the appliance.
79