Troubleshooting; Function Sequence And Possible Faults - Viessmann VITODENS 100-W Installation And Service Instructions Manual

Troubleshooting

Function sequence and possible faults

Control unit issues
a heat demand
yes
Fan starts
yes
Ignition
yes
Gas train opens
yes
Ionisation current
builds (higher than
2 µA)
Symbol A
yes
Burner in opera-
tion
26
Display
no
After approx. 51 s
fault F9
no
Fault F4
no
Fault F4
no
Fault F4
no Stops below the set
boiler water tem-
perature and
restarts immedi-
ately
no
Measures
Increase set value
and ensure heat is
drawn off
Check fan, fan
connecting cables,
power to the fan
and fan control
Check connection
to ignition module
Check gas train
(control voltage
230 V); check gas
supply pressure
Measure ionisa-
tion current, check
electrode adjust-
ment and gas line
for airlocks.
Check flue system
for tightness (flue
gas recirculation),
check gas flow
pressure