42
Displayed fault
code
System characteristics
Cause
Measures
F F9
No feedback from fan
External fan power supply
not connected, faulty or
defective. If voltage is
present at connected plug
"
a-Ö
" and the fan does
not start up when plug
"
a-Ö
A" is disconnected,
there is a fault with the
fan. Cable "
a-Ö
A" faulty or
broken.
Relay in the terminal box
does not switch.
Fan blocked (possibly by
foreign bodies).
Check cable"
a-Ö
A" and external
power supply. Replace cable or
fan. Remove foreign bodies.
F FA
Fan runs without demand;
burner control unit in a fault
state.
Fan does not reach idle
state, cable "
a-Ö
A" faulty,
fan faulty, burner control
unit faulty
Wind influence on fan; check flue
outlet and fan. Replace cable
"
a-Ö
A". Replace fan. Replace
burner control unit.
F FB
Burner does not start.
■
Combustion chamber
pressure too high
(LDW2)
■
Condensate backed up
■
Flue gas path blocked
■
Flue gas damper does
not open or close.
■
Burner control unit con-
figured incorrectly
■
Check condensate drain and flue
gas path for blockages.
■
Check flue gas damper.
■
Check motorised flue gas damp-
er operating parameters.
Internal system faults: Displayed fault codes and detailed fault codes
Internal system faults will be shown if the correct pro-
gram sequence can no longer be guaranteed.
Displayed fault
code
System characteristics
Cause
Measures
F E5, F EC,
F ED, F FF
Fault in burner control unit
area
Internal system fault and
EMC
Reset burner control unit. Replace
the burner control unit if the fault
persists.
F FD
Fault in burner control unit
area
See the following table
See the following table
Detailed error codes for F FD
Detailed er-
ror code
Component/signal Cause of fault
Measure
30
Reset button
Programming unit faulty
Wiring
Replace programming unit.
Check wiring.
31
Fuel valve 2 feed-
back
Incorrect return voltage
(e.g. DC voltage)
Actuator faulty
Remove plug from fuel valve 2, reset burner con-
trol unit and check error messages. If F Fd recurs,
replace burner control unit. Otherwise, replace
fuel valve 2.
32
Air pressure switch
1
High switching se-
quence, switch flutters
External voltage
Check flue gas path and combustion. Check set-
ting LDW1. Check burner gauze assembly for
contamination.
Troubleshooting
Fault codes with display on burner control unit
(cont.)
5833296
Diagnosis