Repairs; Control Unit - Viessmann Vitodens 100 Series Installation And Service Instructions Manual

Troubleshooting
Fault display
Displayed System character-
fault code istics
Fb8 Burner locked out
FF1 Burner locked out

Repairs

!
Please note
Residual water will escape when
the boiler or one of the following
components is fitted or
removed:
■ Water-filled pipework
■ Heat exchanger
■ Circulation pumps
70
(cont.)
Cause
Lead break, flue
gas temperature
sensor
Flue gas tempera-
ture too high
■ Plate heat exchanger
■ Components fitted in the heat-
ing water or DHW circuit.
Water ingress can result in dam-
age to other components.
Protect the following compo-
nents against ingress of water:
■ Control unit (in particular in
the service position)
■ Electrical components
■ Plug-in connections
■ Cables and leads
Measures
Check flue gas tempera-
ture sensor (see
page 77).
Check heating system fill
level. Check circulation
pump. Vent the system.
Check flue system.
Turn the ON/OFF switch
off and back on again, or
perform a reset – see
F02.