Troubleshooting; Diagnostic System - Viessmann VITOGAS 100-F Service Instructions Manual

Troubleshooting

Diagnostic system

System char-
acteristics
The boiler will
not start
Burner control
unit enters a
fault state
Control unit faults:
Boiler control unit service instruc-
tions
18
Cause
No voltage
Boiler water tempera-
ture too high
The high limit safety
cut-out has responded
The flue gas monitor-
ing device (if installed)
has responded
Strapping plug CN2 is
missing at the burner
control unit
The gas pressure
switch has responded
and interrupted the gas
supply
No gas available (air in
the supply line)
The pilot burner will not
start
Ionisation current too
low or cable break
Action
■ Check the MCB/fuse and power cable
connections.
■ Check the setting of the switch on the
control unit.
Wait until the boiler water temperature
has dropped by approx. 20 K.
Press the reset button on the control
unit.
Wait approx. 17 min:
■ If the boiler then starts automatically,
check the flue pipe and the chimney.
■ If the boiler does not start automatical-
ly, check the flue gas monitoring device
(see page 16).
Retrofit strapping plug CN2 or a flue gas
monitoring sensor.
Check the gas pressure.
Reset by switching the control unit ON/
OFF switch ON and OFF.
Check the ignition electrode (see
page 14).
Check the gas supply.
■ Check the ionisation current: Min.
3 µA when main burner is operational
(see page 12).
■ Remove the pilot burner and check for
damage (see page 14).