82
Displayed fault
code
System characteristics Cause Measures
F.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 train: Activate "Mini-
mum heating output" for ap-
prox. 4 min in actuator test. If this
causes a fault to occur, replace
BCU burner control unit.
■
In the actuator test, switch from
"Minimum heating output" to
"Maximum heating output". If
this fault occurs during modula-
tion, check the intake screen for
contamination. Replace the fan
unit if necessary.
F.70 Burner in a fault state Internal burner control unit
fault
Replace BCU burner control unit:
See page 100.
F.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.
F.72 Burner in a fault state Fan idle state not reached Reset the appliance.
If fault occurs repeatedly, replace
fan unit.
F.73 Burner in a fault state Internal communication
error
Reset the appliance.
If fault recurs, replace BCU burner
control unit: See page 100.
F.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.
F.77 Burner in a fault state Data memory burner con-
trol unit
Reset the appliance.
If fault recurs, replace BCU burner
control unit: See page 100.
F.89 No central heating and no
DHW heating
Internal circulation pump
blocked
Check circulation pump. Replace if
necessary.
F.91 Function of affected exten-
sion in emergency mode
DIO electronics module
communication error
Check connections to DIO elec-
tronics module and connection to
heat management unit.
Troubleshooting
Fault messages (cont.)
6151778
Service
To Next Page
Loading...
