Viessmann VITOCROSSAL 200 CM2 Service Instructions For Contractors page 42

Troubleshooting
Fault codes
(cont.)
Displayed fault System characteristics
code
F F1 Burner control unit in a fault
state; system cools down
F F3 Ionisation flame monitor re-
ports faulty flame signal dur-
ing start-up or after the post-
purge.
F F4 No flame formation during
safety time; ionisation flame
monitor reports no flame sig-
nal.
F F4 No flame formation during
safety time; ionisation flame
monitor reports no flame sig-
nal.
F F4 No flame formation during
safety time; ionisation flame
monitor reports no flame sig-
nal.
F F4 Poor start-up characteristics;
rotary damper does not
close.
F F4 No flame formation during
safety time, no signal repor-
ted by the ionisation flame
monitor.
F F4 No flame formation during
safety time, no signal repor-
ted by the ionisation flame
monitor.
F F4 No flame formation during
safety time, no signal repor-
ted by the ionisation flame
monitor.
F F5 Air pressure switch not re-
porting any air pressure. Fan
not running.
F F5 Air pressure switch switches
off during operation
42
Cause
Flue gas excess tempera-
ture; excessive gas
throughput
Gas train not gas-tight
(gas is escaping and burn-
ing); incorrect coding card.
Ionisation electrode incor-
rectly adjusted, ionisation
electrode not plugged in,
earth fault of electrode or
cable
Ignition electrodes incor-
rectly adjusted, electrode
earth fault, ignition unit
faulty, burner control unit
faulty
Insulation body of ignition
or ionisation electrode
cracked
Servomotor faulty, servo-
motor connecting cable
faulty, output relay faulty
(burner control unit)
Incorrect gas type selec-
ted
Gas train does not open.
Combustion characteris-
tics not ideal
Air pressure switch faulty,
incorrectly connected or
incorrectly set
Flue gas back pressure;
condensate banked up; air
pressure switch hose faul-
ty; connecting hose leak-
ing
Measures
Wait until temperature falls below
the permissible flue gas tempera-
ture. Reset the burner control unit.
Check water level; check heat ex-
changer surfaces for contamina-
tion; check CO setting; set gas
2
throughput according to rated boil-
er heating output (see connection
values page 66).
Check ionisation path; replace cod-
ing card; replace gas train.
Insert plug of ionisation electrode;
check cable; adjust ionisation elec-
trode (see page 28)
Adjust ignition electrodes (see
page 28); replace ignition unit; re-
place burner control unit.
Replace ignition or ionisation elec-
trode.
Replace the connecting cable. Re-
place the servomotor. Replace
burner control unit.
Select the gas type (see from
page 13)
Check connecting cable. Check
gas train. Replace if necessary.
Adjust the burner (see page 21 on-
wards); if necessary also adjust the
setting screws with the burner in
idle mode to facilitate the burner
start.
Replace air pressure switch. Con-
nect or set correctly.
Remove flue gas back pressure.
Check for backed up condensate.
Reset the burner control unit. Re-
place hose.