Viessmann VITOCROSSAL 200 Service Instructions Manual page 62

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