92
Displayed fault
code
System characteristics
Cause
Measures
F.464
Burner in a fault state
Ionisation current too low
during calibration. Differ-
ential compared to previ-
ous value not plausible.
■
Check ionisation electrode and
connecting cable. Check plug-in
connections for loose contacts.
■
Check whether there is a lot of
dust in the ventilation air (e.g.
from construction work).
■
Check flue system. Remove flue
gas recirculation if required.
■
Check system for condensate
backup.
Reset the appliance.
Note
To prevent water damage, detach
fan unit before removing the burn-
er.
If fault is permanently present, re-
place BCU burner control unit: See
page 100.
Note
Deposits on the electrodes indicate
foreign bodies in the combustion
air. Check the installation room and
flue system for causes of the de-
posits. For example: Laundry de-
tergents, cleaning agents, toilet-
ries, deposits in the ventilation air
supply (chimney).
If burner gauze assembly and ioni-
sation electrode have been re-
placed, also clean fan unit, gas/air
channel and Venturi extension.
F.467
Burner in a fault state
Gas supply insufficient
during calibration Conta-
minated or insufficiently
sized gas line.
■
Test static gas pressure and gas
flow pressure.
■
Check that on-site gas line and
gas flow switch are correctly
sized.
■
Visually inspect gas solenoid
valve inlet and strainer on the in-
let side for contamination.
Reset the appliance.
Note
Contamination from a brazed gas
line, for example, can block up the
gas solenoid valve strainer on the
inlet side.
Troubleshooting
Fault messages
(cont.)
6151778
Service
