Viessmann VITODENS 111-W Installation And Service Instructions Manual page 77

Fault messages
(cont.)
Displayed fault System characteristics
code
349 Burner in a fault state
350, 351 Burner in a fault state
352 Burner in a fault state
353 Shutdown with restart if de-
mand exists
354 Burner in a fault state
355 Burner in a fault state
357 Burner in a fault state
Cause
Air mass rate flow not de-
tected correctly in fan unit.
Ionisation current lies out-
side the permissible range
Combustion CO limit ex-
ceeded
Insufficient gas supply,
burner output reduced
Gas modulation valve tol-
erance outside permissi-
ble range
Analogue signal reference
check: Flame signal is al-
ready present at burner
start
Insufficient gas supply
Troubleshooting
Measures
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.
Check the gas supply.
Optically check input-side screen
in the gas solenoid valve for con-
tamination.
Reset the appliance.
Replace gas fan unit.
Replace the HBMU heat manage-
ment unit: See chapter "Replacing
the HBMU heat management unit".
Check that the main gas valve
■
and the gas shut-off valve are
open.
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 does not
■
drop, check the cable to the fan
unit. Check that the coil resist-
ance at the fuel valve is approx.
4 k .
Ω
Check the ignition electrode for
■
damaged insulation.
Reset the appliance.
77