72
Displayed fault
code
System characteristics
Cause
Measures
468
Burner in a fault state
Ionisation current too high
during calibration
Check gap between ionisation
electrode and burner gauze as-
sembly.
Check whether there is a lot of
dust in the ventilation air (e.g. from
construction work).
Reset the appliance.
Note
Deposits on the electrodes indicate
foreign bodies in the ventilation 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.
471
No heat demand
System pressure sensor
not available, lead break
or short circuit
■
Check system pressure sensor
(plug
aND
).
■
Check lead and plug-in connec-
tion.
■
Check whether the supply volt-
age to the sensor is 5 V .
474
Burner in a fault state
Error in scheduled pro-
gram run monitoring
Reset the appliance.
If the fault occurs repeatedly, re-
place the HBMU heat management
unit. See chapter "Replacing the
HBMU heat management unit".
527, 528
Burner in a fault state
Incorrect HBMU heat
management unit parame-
ter set
Overwrite (flash) the HBMU heat
management unit with the correct
parameter set.
540
Burner in a fault state
Condensate backup in the
heat cell
■
Check system for condensate
backup.
■
Check the condensate drain and
trap.
■
Replace insulation blocks, elec-
trodes and burner gauze assem-
bly if necessary.
Note
To prevent water damage, detach
fan unit before removing the burn-
er.
Reset the appliance.
574
Normal operation without
room influence
Room temperature sen-
sor, heating circuit 1 not
available
Check external room temperature
sensor for heating circuit or room
temperature sensor on remote
control unit.
Check setting of parameter 933.6
Troubleshooting
Fault messages
(cont.)
6179762
Diagnosis
