Troubleshooting; Function Sequence And Possible Faults - Viessmann VITODENS 050-W Installation And Service Instructions Manual

Troubleshooting

Function sequence and possible faults

Control unit is-
sues a heat de-
mand
Yes
Fan starts
Yes
Ignition
Yes
Gas train opens
Yes
Ionisation current
builds (above
2 µA)
Symbol A
50
Shown on display
No
No
After approx.
1 min, fault F9
No Fault F4
No
Fault F4
No
Fault F4
Action
Increase set value
and ensure heat is
drawn off
Check the fan, fan
connecting ca-
bles, fan power
supply and fan
control
Check the ignition
module connec-
tion
Check the gas
train (230 V con-
trol voltage) and
gas supply pres-
sure
Check the ionisa-
tion current and
electrode adjust-
ment, check the
condensate drain
and check the gas
line for airlocks.