Viessmann VITODENS 100-W Installation And Service Instructions Manual page 39

Fault messages on the display
Displayed System characteris-
fault code tics
F2 Burner in a fault
state
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
The temperature
limiter has respon-
ded
Flame signal is al-
ready present at
burner start
No flame signal
Fuel valve closes
too late
Fan speed too low
during burner start
Fan not at stand-
still
Electrical fan con-
trol (control unit)
faulty
Troubleshooting
Measures
Check heating system fill
level. Check circulation
pump. Vent the system.
Check the temperature
limiter and connecting
leads (see page 46).
Press "Reset" (see
page 40).
Check ionisation elec-
trode and connecting ca-
ble.
Press "Reset" (see
page 40).
Check the ionisation elec-
trode and connecting ca-
bles, check the gas pres-
sure, check the gas train,
ignition, ignition module
and condensate drain.
Press "Reset" (see
page 40).
Check gas train. Check
both control paths.
Press "Reset" (see
page 40).
Check fan, fan connecting
cables and power supply;
check fan control.
Press "Reset" (see
page 40).
Check fan, fan connecting
cables and fan control.
Press "Reset" (see
page 40).
Check fan connecting ca-
ble; replace if required or
replace control unit
39