Viessmann Vitovalor PT2 Installation And Service Instructions For Contractors page 121

Fault messages on the gas condensing...
Control unit System characteristics
message
F.305/C2F2 No power generation
F.341 Fuel cell in emergency mode
F.342 Burner in a fault state
F.343 Fuel cell only heats the cylin-
der module.
F.344 Fuel cell only heats the cylin-
der module.
F.345 Burner locked out
F.346 Burner in a fault state
F.348 Burner in a fault state
(cont.)
Cause
Fault, stack voltage 3 (fuel
cell)
Communication error, fuel
cell
Communication error,
burner control unit
Short circuit, common re-
turn temperature sensor
Lead break, common re-
turn temperature sensor
Temperature limiter has
responded.
Ionisation current calibra-
tion error
Gas modulation valve
Troubleshooting
Measures
Check balanced flue system for:
■
– Flue gas recirculation
– Leaks
Check ventilation air supply for:
■
– Ingress of flue gas due to non-
compliance with chimney clear-
ances, e.g. by a solid fuel boil-
er
– Outgassing/contamination in
the air supply system (e.g. sili-
cones, oils, paints, detergents,
deposits, etc.)
If faults recur, contact Viessmann
Technical Service.
Note
Fault message can only be reset
on the programming unit of the fuel
cell module.
Check the connecting cable to the
fuel cell.
Check connecting lead to the burn-
er control unit (BCU).
Reset device.
Check return temperature sensor.
Check return temperature sensor.
Ensure adequate heat transfer.
Check the gas supply pressure.
■
Check input-side screen on the
gas train for contamination.
Check ionisation electrode for
■
contamination.
Check the distance of the ionisa-
tion electrode for burner gauze
assembly (see page 79).
Reset device.
Check flue system or flue gas re-
■
circulation.
Check connecting cable on fan
■
unit.
Check impeller for ease of opera-
■
tion.
Reset device.
Check connecting cable for gas
train for damage.
Check flue system for flue gas con-
gestion.
Check gas train.
Reset device.
121