101
Fault code dis-
played
System characteristics
Cause
Measures
FC
Burner in a fault state
Gas train faulty, modula-
tion valve control faulty or
flue gas path blocked
Check connecting cables to the
gas train for damage.
Check gas train.
Check flue system for blockages or
constrictions.
Press reset button
R
.
Fd
Burner in a fault state
Burner control unit fault
Check ignition electrode, ionisation
electrode and connecting cables.
Check whether a strong interfer-
ence (EMC) field exists near the
appliance.
Press reset button
R
.
If the fault occurs sporadically, re-
place the coding card.
Replace control unit if fault is per-
manent.
FE
Burner blocked or in a fault
state
EEPROM error, PCB
Press reset button
R
. Replace con-
trol unit if fault persists.
FE
Burner in a fault state and ad-
ditional fault B7 is displayed
Boiler coding card missing Insert the boiler coding card.
Press reset button
R
.
Replace control unit if fault per-
sists.
FF
Burner blocked or in a fault
state
Internal fault or reset but-
ton
R
disabled
Restart the appliance. Replace the
control unit if the appliance will not
restart.
Maintenance
!
Please note
Residual water will escape when the boiler or
one of the following components is fitted or
removed:
■
Water-filled pipework
■
Circulation pumps
■
Plate heat exchanger
■
Components fitted in the heating water or
DHW circuit
Water ingress can result in damage to other
components.
Protect the following components against
ingress of water:
■
Control unit (in particular in the service posi-
tion)
■
Electrical components
■
Plug-in connections
■
Cables and leads
Putting the control unit into the service position
If required for commissioning and servicing, the control
unit can be put into a different position.
Troubleshooting
Fault codes
(cont.)
5789 302 GB
Diagnosis
Summary of Contents for B2TB
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