Viessmann Vitocrossal 200 CM2 500 Service Instructions Manual page 60

Troubleshooting
Fault Codes
(continued)
Displayed System Characteristics
Fault Code
F F4 No flame builds during safety
time; ionization flame monitor
reports no signal
F F5 Air pressure switch 1 shows
no air pressure, fan does not
operate
F F5 Air pressure switch 1 switches
off during operation
F F6 Gas pressure switch shows no
gas pressure
F F7 Fan pressure is created during
the idle state check of air
pressure switch 1
F F7 Contact of air pressure switch
1 not closed in 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
F F9 Varying fan speed
F F9 No fan feedback
F FA Fan runs without demand;
burner control unit in a fault
state
F Fb Burner not starting. Combustion
chamber pressure too high;
burner control unit in a fault
state
60
Vitocrossal 200, CM2 400, 500 and 620 Service
Cause
Combustion characteristics not
ideal
Air pressure switch 1 faulty,
incorrectly connected or
incorrectly set
Flue gas back pressure;
condensate built up; air pressure
switch 1 hose faulty; connecting
hose leaking
Gas shut-off valve closed; gas
pressure switch faulty; multiple
problems with gas supply
Wind influence on fan
Air pressure switch 1 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
Fan faulty; external power supply
to fan not connected or faulty;
cable "a-ÖA" faulty or broken;
fan blocked (possibly by a foreign
object)
Fan has not stopped; cable "a-ÖA"
faulty; fan faulty; burner control
unit faulty
Flue gas path or condensate path
blocked off. Excessive combustion
chamber pressure (LDW2)
Motorized vent damper not
configured with control (if used)
Measures
Adjust the burner (see from page
15, if necessary, also adjust the
setting screws when the burner is
OFF to be able to start the burner)
Replace air pressure switch 1,
connect or set correctly
Remove flue gas back pressure;
check if condensate banked up;
reset burner control unit; replace
hose
Open gas shut-off valve; check
gas flow pressure; replace gas
filter if required; reset burner
control unit; replace gas valve
Check flue outlet or (chimney)
Replace air pressure switch 1
Adjust gas type (see page 12)
Check burner gauze assembly;
replace if damaged
Adjust burner (see from page 46)
Check cables; replace fan if
required
Replace fan or burner control unit
Check cable; replace cable "a-ÖA"
or fan if required
Check cable "a-ÖA", check
external power supply; replace
cable or fan; remove foreign
object
Wind influence on fan; check
flue outlet and fan; replace cable
"a-ÖA", replace fan; replace burner
control unit
Check flue gas path or condensate
path and clean if required
See for flue gas damper setting
(common vent system)