185
5790 733 - 07
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Burner Fault Codes
(continued)
Troubleshooting
Displayed
fault code
System characteristics
Cause
Measures
F5
Air pressure switch shows no air
pressure, fan not running.
Air pressure switch is faulty,
incorrectly connected or
incorrectly set.
Replace air pressure switch,
connect or set correctly.
Air pressure switch switches off
during operation.
Flue gas back pressure;
condensate backed up; air
pressure switch hose faulty;
connecting hose leaking.
Remove flue gas back pressure;
check if condensate backed up;
reset burner control unit; replace
hose.
F6
Gas pressure switch notifies no
gas pressure.
Gas shut-off valve closed;
gas pressure switch faulty;
multiple problems with gas
supply.
Open gas shut-off valve; check
gas flow pressure; replace gas
filter if required; reset burner
control unit; replace gas valve.
F7
Fan pressure is produced during
the air pressure switch idle state
check.
Wind influence on fan.
Check the flue draught (chimney)
Air pressure switch contact is not
in the idle state.
Air pressure switch faulty.
Replace the air pressure switch.
F8
Flame extinguishes during
operation.
Burner gauze assembly faulty.
Check burner gauze assembly;
replace if damaged.
Flame extinguishes during
operation.
Combustion characteristics not
ideal.
Adjust burner
(see boiler service instructions).
F9
Fan not running; fan speed not
reached.
Fan faulty; cables are faulty or
broken.
Check cables and replace the fan
if required
Status duration too long, fan
ramp-up.
Internal fault; fan cannot reach its
set value.
Replace fan or burner control unit.
Varying fan speed
Fan faulty, cable
a-Ö
A
faulty
or broken. Check cable
a-Ö
A
;
check external power supply;
replace the cable or fan; remove
foreign bodies.
Check cable; replace cable
a-Ö
A
or fan.
No fan feedback.
Fan faulty, external fan power
supply not connected or faulty
cable
a-Ö
A
or cable broken, fan
blocked (poss. by foreign bodies).
Check cable
a-Ö
A
; check
external power supply; replace
cable or fan; remove foreign
bodies.
Fa
Fan runs without demand; burner
control unit in a fault state.
Fan does not reach idle state,
cable
a-Ö
A
faulty, fan faulty,
faulty burner control unit.
Fan subject to wind influence,
check flue outlet and fan, replace
cable
a-Ö
A
, replace fan, replace
burner control unit.
Fd
Burner control unit in a fault
state; system cools down; burner
control unit locked out.
Burner control unit in a fault
state.
Read off fault at the burner
control unit display and
programming unit (boiler service
instructions).
Fault message to the burner control unit:
Note:
If LON participant faults occur, “Fault participant”...
is displayed.
