Viessmann B1HF Installation And Service Instructions Manual page 72

Troubleshooting
Fault messages
(cont.)
Displayed fault System characteristics
code
345 Burner locked out, automatic
enabling after appliance cool-
down. Independent restart
346 Burner in a fault state
348 Burner in a fault state
349 Burner in a fault state
350, 351 Burner in a fault state
352 Burner in a fault state
72
Cause
Temperature limiter has
responded.
Ionisation current calibra-
tion error
Gas modulation valve
Air mass rate flow not de-
tected correctly in fan unit.
Ionisation current lies out-
side the permissible range
Combustion CO limit ex-
ceeded
Measures
Ensure adequate heat transfer.
■
Check heating system fill level.
■
Check pre-charge pressure in di-
■
aphragm expansion vessel. Ad-
just to required system pressure.
Check whether flow rate is suffi-
■
cient (circulation pump).
Check function of 3-way diverter
■
valve. Vent the system.
If the fault occurs during DHW
heating: Check DHW cylinder or
plate heat exchanger for contami-
nation and scaling.
Check the gas supply pressure.
■
Check gas solenoid valve strain-
■
er on the inlet side for contami-
nation.
Check ionisation electrode for
■
contamination.
Check flue system. Remove flue
■
gas recirculation if required.
Check the condensate drain
■
(condensate blockage).
Reset the appliance.
If several heat generators are con-
nected to a common flue system:
Check whether "Multiple connec-
tions" is set in the commissioning
assistant.
Check the flue system for unre-
stricted flow.
If fault remains, replace gas fan
unit.
Check for dust contamination in
■
the supply air.
Check burner gauze assembly
■
for contamination.
Reset the appliance. If the fault oc-
curs repeatedly, replace the gas
fan unit.
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
Check entire flue gas path for the
following:
Leaks
■
Flue gas back pressure caused
■
by water pocket (if flue system
fall is insufficient)
Constrictions
■
Blockages
■
Repair flue system if necessary.
Reset the appliance.