Viessmann VITODENS 100-W Installation And Service Instructions Manual page 40

Troubleshooting
Fault messages on the display
Displayed System characteris-
fault code tics
Fd Burner blocked
FF Burner blocked
Initiating a reset
r
40
(cont.)
Cause
Fault, burner con-
trol unit
Fault, burner con-
trol unit
Turn rotary selector "rt" to "U
RESET" for less than 2 s, then back into
the control range.
Measures
Check ignition electrodes
and connecting cables.
Check whether a strong
interference (EMC) field
exists near the appliance.
Press "Reset" (see
page 40).
Replace control unit if
fault persists.
Check ignition electrodes
and connecting cables.
Check whether a strong
interference (EMC) field
exists near the appliance.
Press "Reset" (see
page 40).
Replace control unit if
fault persists.