Viessmann B1HE-199 - Page 76

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Vitodens 100-W, B1HE/B1KE Combi Installation/Service
Fault Messages
(continued)
Troubleshooting
Displayed
fault code
System characteristics Cause Measures
F.346 Burner in a fault state Ionization current
calibration error
 Check the gas supply pressure.
 Check gas solenoid valve strainer on the inlet side
for contamination.
 Check ionization electrode for contamination.
 Check flue system. Remove flue gas recirculation
if necessary.
 Check the connecting cable to the fan unit.
 Check whether condensate is backed up.
Reset the boiler.
F.348 Burner in a fault state Gas modulation valve If several boilers are connected to a common flue
system:
Check whether “Multiple connections” is set in the
commissioning assistant.
Check the flue system for unrestricted flow.
If the fault persists, replace the gas fan unit.
F.349 Burner in a fault state Air mass flow rate not
detected correctly in
fan unit.
 Check for dust contamination in the ventilation air.
 Check flame body assembly for contamination.
Reset the boiler. If the fault occurs repeatedly, replace
the gas fan unit.
F.350,
F.351
Burner in a fault state Ionization current
lies outside the
permissible range
Replace BCU burner control unit:
See page 89.
F.352 Burner in a fault state CO limit within boiler
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 boiler.
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 contamination.
Reset the boiler.
F.354 Burner in a fault state Gas modulation valve
tolerance outside
permissible range
Replace gas fan unit.
F.355 Burner in a fault state Analogue signal
reference check:
Flame signal is already
present at burner start.
Replace BCU burner control unit:
See page 89.
F.357 Burner in a fault state Insufficient gas supply
 Check that the gas shut-off valve is open.
 Optically check input-side screen in the gas solenoid
valve for contamination.
 Test static gas pressure and gas flow pressure.
 Check that on-site gas line and gas flow switch are
correctly sized.
Note: If the building pressure regulator has a leak, you
may notice rising pressure when the burner is idle.
When the system is restarted, the gas flow switch may
trip. If the static pressure doesn’t drop, check cable to
the fan unit. Check whether the coil resistance at the
fuel valve is approx. 4 k Ω (plug 35, contact 2 and 4).
Check the ignition electrode for damaged insulation.
Reset the boiler.