Viessmann Vitocrossal 200 Service Instructions Manual page 42

Troubleshooting
Diagnosis
(cont.)
Fault code System character-
istics
25 No flame signal
after the safety peri-
od; the ionisation
flame monitor re-
ports no flame sig-
nal
26 The ionisation flame
monitor reports ex-
ternal light ingress
during the start or
after the post purge
26 The ionisation flame
monitor reports ex-
ternal light ingress
during the start or
after the post purge
26 The ionisation flame
monitor reports ex-
ternal light ingress
during the start or
after the post purge
26 The ionisation flame
monitor reports ex-
ternal light ingress
during the start or
after the post purge
27 Flame extinguishes
during operation
27 Flame extinguishes
during operation
27 Flame extinguishes
during operation
27 Flame extinguishes
during operation
29 Burner control unit
fault
42
Cause Remedy
Incorrect para- Adjust the parameter set
meter set se- (see page 35 to 36).
lected
Ignition cables Remove the short cir-
short circuited cuit.
Short circuit at the Remove the short cir-
ionisation cables cuit.
or electrode
Gas combination Replace the gas combi-
valve leaks nation valve.
Incorrect para- Adjust the parameter set
meter set se- (see page 35 to 36).
lected
Incorrect gas type Adjust the gas type (see
selected page 9).
Burner gauze as- Replace the burner
sembly faulty gauze assembly.
Incorrect para- Adjust the parameter set
meter set se- (see page 35).
lected
Combustion char- Adjust the burner (see
acteristics not from page 14).
ideal
Internal fault of Replace the burner con-
the gas pressure trol unit.
switch input