Viessmann Vitocrossal 200 Series Service Instructions Manual page 43

Fault codes
(cont.)
Fault code dis- System characteristics
played
F F4 Poor start-up characteristics
(start enrichment). Solenoid
valve not switching.
F F4 Flame does not build during
the safety time, no signal re-
ported by the ionisation flame
monitor.
F F4 Flame does not build during
the safety time, no signal re-
ported by the ionisation flame
monitor.
F F4 Flame does not build during
the safety time, no signal re-
ported by the ionisation flame
monitor.
F F5 Air pressure switch 1 reports
no air pressure, fan not run-
ning.
F F5 Air pressure switch 1
switches off during operation.
F F5 When phase P is completed,
the boiler enters a fault state
F F6 Gas pressure switch reports
no gas pressure.
F F7 Fan pressure is created dur-
ing the idle state check of air
pressure switch 1.
F F7 Contact of air pressure switch
1 not in idle state
F F8 Flame tears off during opera-
tion.
Cause
Compensation lines not
connected, solenoid valve
or solenoid valve power
cable faulty, output relay
of burner control unit faul-
ty
Incorrect gas type selec-
ted
Gas train does not open.
Combustion characteris-
tics not ideal
Air pressure switch 1 faul-
ty, incorrectly connected
or incorrectly set
Flue gas back pressure,
condensate banked up, air
pressure switch 1 hoses
faulty, connecting hose
leaking, excessive pres-
sure drop on the supply
air side.
Air pressure switch 1 faul-
ty, incorrectly connected,
incorrectly set or burner
gauze assembly contami-
nated.
Gas shut-off valve closed;
gas pressure switch faulty;
multiple problems with gas
supply
Wind influence on fan
Air pressure switch 1 faul-
ty
Incorrect gas type selec-
ted
Troubleshooting
Measures
Check compensation lines and
connections (see page 50); re-
place compensation lines. Replace
solenoid valve. Replace burner
control unit.
Adjust gas type (see page 11).
Check connecting cable. Check
the gas train and replace if re-
quired.
Adjust burner setting. If necessary
also adjust the setting screws
when the burner is off to facilitate
the burner start.
Replace air pressure switch 1, con-
nect or adjust correctly.
Remove flue gas back pressure.
Check for backed up condensate.
Reset burner control unit. Replace
hose. Check/clean air supply hose
or air filter.
Turn the air pressure switch down
to 0.5 mbar. When the burner
starts, bring it to full load and
measure the gas throughput.
If the output is not achieved, clean
the burner gauze assembly with
compressed air and replace if nec-
essary.
Replace air pressure switch 1 and
connect correctly. Set the air pres-
sure switch according to the speci-
fication on page 50.
Open the gas shut-off valve. Check
gas supply pressure. Replace gas
filter if required. Reset burner con-
trol unit. Replace gas train.
Check the flue draught (stack).
Replace air pressure switch 1.
Adjust gas type (see page 11).
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