Viessmann Vitodens 100-W Installation And Service Instructions Manual page 36

Troubleshooting
Fault messages on the display
Fault code System characteris-
on the dis- tics
play
Fd Burner blocked
FF Burner blocked
Press reset
r
36
(cont.)
Cause Measures
Burner control unit Check ignition electrodes
fault and connecting cables.
Check whether a strong
interference (EMC) field
exists near the equip-
ment.
Press "Reset" (see
page 36).
Replace control unit if the
fault persists.
Burner control unit Check ignition electrodes
fault and connecting cables.
Check whether a strong
interference (EMC) field
exists near the equip-
ment.
Press "Reset" (see
page 36).
Replace control unit if the
fault persists.
Turn rotary selector "rt" less than 2 s
to "URESET", then back to the control
range.