Viessmann Vitodens 050-W Installation And Service Instructions Manual page 41

Fault display showing
Fault code System characteris-
showing tics
F3 Burner in a fault
state
F4 Burner in a fault
state
F8 Burner in a fault
state
F9 Burner in a fault
state
FA Burner in a fault
state
FC Burner blocked
(cont.)
Cause
Flame signal is al-
ready present at
burner start
No flame signal de-
tected
Fuel valve closes
too late
Fan speed too low
during burner start
Fan idle state not
reached
Electrical fan con-
trol (control unit)
faulty
Troubleshooting
Measures
Check ionisation elec-
trode and connecting ca-
ble.
Press "Reset" (see
page 42).
Check the ignition/ionisa-
tion electrode and con-
necting cables, check the
gas pressure, check the
gas train, ignition, ignition
module and condensate
drain.
Press "Reset" (see
page 42).
Check gas train. Check
both control paths.
Press "Reset" (see
page 42).
Check fan, fan connecting
cables and power supply;
check fan control.
Press "Reset" (see
page 42).
Check fan, fan connecting
cables and power supply;
check fan control.
Press "Reset" (see
page 42).
Check fan connecting ca-
ble; replace if required, or
replace control unit.
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