Viessmann VITODENS 100-W Installation And Service Instructions Manual page 55

Fault messages
(cont.)
Displayed fault System characteristics
code
372 Burner in a fault state
373 Burner in a fault state
377 Burner in a fault state
378 Burner in a fault state
379 Burner in a fault state
Cause
Repeated flame loss dur-
ing calibration
Heat transfer too low dur-
ing calibration
Temperature limiter has
shut down.
Post-processing ionisation
current calibration: Stabili-
sation conditions for post-
calibration not reached
Flame loss during stabili-
sation or operating phase
Flame signal not present
or insufficient
Troubleshooting
Measures
Check ionisation electrode and
■
connecting cable.
Check plug-in connections for
■
loose contacts.
Check flue system. Remove flue
■
gas recirculation if necessary.
Check system for condensate
■
backup.
Visually inspect the gas solenoid
■
valve inlet and the inlet strainer
for dirt.
Note
To prevent water damage, detach
fan unit before removing the burn-
er. Deposits on the electrodes indi-
cate foreign bodies in the combus-
tion 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 ionisation electrode
have been replaced, 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.
Check function of 3-way diverter
■
valve. Vent the system.
Check function of flow sensor.
■
Reset the appliance.
Check gas type setting. If the fault
occurs repeatedly, replace the
HBMU heat management unit. See
chapter "Replacing the HBMU heat
management unit".
Reset the appliance.
Check gas supply (gas pressure
■
and gas flow switch).
Check flue gas recirculation.
■
Check for contamination of ioni-
■
sation electrode and burner
gauze assembly.
Reset the appliance.
Check ionisation electrode con-
■
necting cable for damage and
firm seating.
Check ionisation electrode. Re-
■
place if necessary.
Reset the appliance.
55