60
Displayed fault
code
System characteristics
Cause
Measures
69
Burner in a fault state
Ionisation current lies out-
side the permissible range
Check ionisation electrode for the
following:
■
Check whether insulation block is
touching electrode ceramic.
■
Check gas solenoid valve: In the
service menu under "b.6", set the
burner output to the lower heat-
ing output for approx. 4 min. If
the fault occurs, replace the
HBMU heat management unit.
See chapter "Replacing the
HBMU heat management unit".
■
Change the burner output from
lower to upper heating output in
the service menu under "b.6". If
this fault occurs during modula-
tion, check the inlet strainer for
contamination. Replace the fan
unit if necessary.
70
Burner in a fault state
HBMU heat management
unit internal fault
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
71
Burner in a fault state
Fan speed too low
■
Check fan for blockage.
■
Check setting for gas type and
flue system.
Reset the appliance.
72
Burner in a fault state
Fan idle state not reached
■
Reset the appliance.
■
If the fault occurs repeatedly, re-
place the fan unit.
73
Burner in a fault state
Internal communication
error
Reset the appliance.
If the fault occurs repeatedly, re-
place the HBMU heat management
unit. See chapter "Replacing the
HBMU heat management unit".
74
Burner locked out.
Internal circulation pump off.
No central heating and no
DHW heating
System pressure too low
Top up with water.
Vent the system.
If the fault occurs repeatedly:
■
Check system pressure sensor
with external pressure gauge.
■
Check diaphragm expansion
vessel pre-charge pressure.
■
Check settings for set system
pressure and range.
75
Burner in a fault state
No flow rate
■
Open BDF valves.
■
Top up with water.
■
Replace the flow sensor (if instal-
led). Replace the pump.
77
Burner in a fault state
HBMU heat management
unit data memory
Reset the appliance.
If the fault occurs repeatedly, re-
place the HBMU heat management
unit. See chapter "Replacing the
HBMU heat management unit".
Troubleshooting
Fault messages
(cont.)
6179762
Diagnosis