Viessmann B2HF - Page 93

93
Displayed fault
code
System characteristics Cause Measures
F.346 Burner in a fault state Ionisation current calibra-
tion error
■
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 connecting cable to
the fan unit.
■
Check impeller for ease of opera-
tion.
Reset the appliance.
F.348 Burner in a fault state Gas modulation valve 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.
F.349 Burner in a fault state Air mass rate flow not de-
tected correctly in 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.
F.350, F.351 Burner in a fault state Ionisation current lies out-
side the permissible range
Replace BCU burner control unit
(see page 109).
F.352 Burner in a fault state CO limit within appliance
exceeded
Check entire flue gas path for the
following:
■
Flue gas recirculation
■
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.
F.353 Burner shutdown with restart
if demand exists
Insufficient gas supply,
burner output reduced
Check the gas supply.
Optically check input-side screen
in the gas solenoid valve for con-
tamination.
Reset the appliance.
F.354 Burner in a fault state Gas modulation valve tol-
erance outside permissi-
ble range
Replace gas fan unit.
F.355 Burner in a fault state Analogue signal reference
check: Flame signal is al-
ready present at burner
start.
Replace BCU burner control unit
(see page 109).
Troubleshooting
Fault messages (cont.)
5593201
Diagnosis