62
Displayed
fault code
System characteris-
tics
Cause
Measures
F F5
Air pressure switch
switches off during
operation
Flue gas back
pressure; conden-
sate banked up; air
pressure switch
hose faulty; con-
necting hose leak-
ing
Remove flue gas back
pressure; check if con-
densate banked up; reset
burner control unit; re-
place hose
F F6
Gas pressure switch
notifies no gas pres-
sure
Gas shut-off valve
closed; gas pres-
sure switch faulty;
multiple problems
with gas supply
Open gas shut-off valve;
check gas flow pressure;
replace gas filter if re-
quired; reset burner con-
trol unit; replace gas train
F F7
Fan pressure is pro-
duced during the air
pressure switch idle
state check
Wind influence on
fan
Check flue outlet (chim-
ney)
F F7
Air pressure switch
contact is not in the
idle state
Air pressure switch
faulty
Replace air pressure
switch
F F8
Flame extinguishes
during operation
Incorrect gas type
selected
Select the gas type (see
from page 11)
F F8
Flame extinguishes
during operation
Burner gauze as-
sembly faulty
Check burner gauze as-
sembly; replace if dam-
aged
F F8
Flame extinguishes
during operation
Combustion char-
acteristics not ide-
al
Adjust burner (see from
page 27)
F F9
Fan not running; fan
speed not reached
Fan faulty; cables
are faulty or bro-
ken
Check cables; replace fan
if required
F F9
Status duration too
long, fan ramp-up
Internal fault; fan
cannot reach its set
value
Replace fan or burner
control unit
Troubleshooting
Fault codes
(cont.)
5794 780 GB