Viessmann Vitocrossal 300 Service Instructions Manual page 32

Troubleshooting
Diagnostics
(cont.)
Fault System
code characteristics
display
25 No flame after safety
time, ionisation
flame monitor
signals no flame
26
Ionisation flame
monitor signals o o s g a s
external light during
start−up or
post−purge
27
Flame extinguishes
during operation g ope a o
32
Cause
Ionisation electrode
incorrectly adjusted
Cores L1 and N at
control unit mains
supply interchanged
Ignition electrodes
incorrectly adjusted
Insulation body of
ignition electrode
cracked
Incorrect gas type
selected
Gas train does not
open
Ionisation cable or
electrode short
circuited
Ignition cables short
circuited
l li h d i
Ionisation cable or
electrode short
circuited
Gas combination
valve leaking
Incorrect gas type
selected
Burner gauze
assembly faulty
Remedy
Adjust ionisation
electrode (see
page 18)
Check mains supply
and swap cores
Adjust ignition
electrodes (see
page 18)
Replace ignition
electrodes
Adjust gas type (see
page 9)
Check and replace
combination valve if
necessary
Straighten bent
electrodes or
remove
contamination,
remove short circuit
from the cable
Remedy short circuit
Remedy short circuit
Replace gas
combination valve
Adjust gas type (see
page 9)
Replace burner
gauze assembly