Viessmann Vitotronic 300 Installation And Service Instructions Manual page 48

Troubleshooting
Fault Codes
(continued)
Displayed System characteristics
fault code
F5 Air pressure switch shows no air
pressure, fan not running.
Air pressure switch
shows no air pressure,
fan not running.
F6 Gas pressure switch notifies no
gas pressure.
F7 Fan pressure is produced during
the air pressure switch idle
state check.
Air pressure switch contact is
not in the idle state.
F8 Flame extinguishes during
operation.
Flame extinguishes during
operation.
Flame extinguishes during
operation.
F9 Fan not running; fan speed not
reached.
Status duration too long, fan
ramp-up.
Varying fan speed
No fan feedback.
FA Fan runs without demand; burner
control unit in a fault state.
FD Burner control unit in a fault
state; system cools down; burner
control unit locked out.
Note: In case of participant faults, "Participant fault" ...
is displayed.
48
Vitotronic 300, GW5B Installation and Service
Cause
Air pressure switch is faulty,
incorrectly connected or
incorrectly set.
Air pressure switch is faulty,
incorrectly connected or
incorrectly set.
Gas shut-off valve closed; gas
pressure switch faulty; multiple
problems with gas supply.
Wind influence on fan.
Air pressure switch faulty.
Incorrect gas type selected.
Burner gauze assembly faulty.
Combustion characteristics not
ideal.
Fan faulty; cables are faulty or
broken.
Internal fault; fan cannot reach
its set value.
Fan faulty, cable a-ÖA faulty or
broken. Check cable a-ÖA;
check external power supply;
replace the cable or fan; remove
foreign bodies.
Fan faulty, external fan power
supply not connected or faulty
cable a-ÖA or cable broken, fan
blocked (poss. by foreign bodies).
Fan does not reach idle state,
cable a-ÖA faulty, fan faulty,
faulty burner control unit.
Burner control unit in a fault
state.
Measures
Remove flue gas back pressure;
check if condensate banked up;
reset burner control unit; replace
hose.
Replace air pressure switch,
connect or set correctly
Open gas shut-off valve; check
gas flow pressure; replace gas
filter if required; reset burner
control unit; replace gas valve.
Check the flue draught (chimney)
Replace the air pressure switch.
Select gas type (see boiler
service instructions).
Check burner gauze assembly;
replace if damaged.
Adjust burner (see boiler service
instructions).
Check cables and replace the fan
if required
Replace fan or burner control
unit.
Check cable; replace cable
a-ÖA or fan if necessary.
Check cable a-ÖA; check
external power supply; replace
cable or fan; remove foreign
bodies.
Fan subject to wind influence,
check flue outlet and fan, replace
cable a-ÖA, replace fan,
replace burner control unit.
Read off fault at the BCU display
and programming unit (boiler
service instructions).