Viessmann Vitodens 100 Installation And Service Instructions Manual page 59

Fault finding
(cont.)
Yes
Ignition
Yes
Gas combina-
tion valve opens
Yes
Ionisation cur-
rent builds
(higher than
2 µA)
Symbol A
Yes
Burner in opera-
tion
No Fault
F4
Fault
No
F4
Fault
No
F4
Stops below set
boiler tempera-
ture and restarts
Troubleshooting
Check the con-
nection to the igni-
tion module
Check the gas
train (control vol-
tage 230 V) and
gas supply pres-
sure
Check the ionisa-
tion current, check
the electrode ad-
justment and the
gas pipe for air-
locks.
Check flue gas
system for sound-
ness (flue gas re-
circulation), check
gas flow pressure
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