60
Displayed
fault code
System characteris-
tics
Cause
Measures
F EF
Burner control unit in
a fault state
Internal error in
feedback from gas
safety valves; out-
put relay does not
respond
Reset burner control unit;
replace burner control
unit
F F0
*1
Emergency operation
according to internal
default
Communication er-
ror KM BUS burner
control unit
Check the KM BUS cable
plug for firm seating;
check all KM BUS cables
F F1
Burner control unit in
a fault state
Flue gas excess
temperature; ex-
cessive gas
throughput
Wait until temperature
falls below the permiss.
flue gas temperature. Re-
set burner control unit.
Check water level; check
heat exchanger surfaces
for contamination; check
CO
2
setting; set gas
throughput according to
rated boiler heating output
(see connection values
page 91).
F F2
Burner control unit in
a fault state; system
cools down
Excessive boiler
water temperature
Wait until temperature
falls below the permiss.
boiler water temperature.
Reset burner control unit.
F F3
Ionisation flame mon-
itor reports faulty
flame signal during
start-up or after the
post-purge
Gas train not gas-
tight (gas is escap-
ing and burning);
incorrect coding
card
Check ionisation path; re-
place coding card; re-
place gas train
F F4
No flame formation
during safety time;
ionisation flame mon-
itor reports no flame
signal
Ionisation elec-
trode incorrectly
adjusted; ionisa-
tion electrode not
plugged in. Earth
leakage of elec-
trode or cable
Insert plug of ionisation
electrode; check cables;
adjust ionisation elec-
trode (see page 40)
*1
Only displayed on the control unit.
Troubleshooting
Fault codes
(cont.)
5794 780 GB
Summary of Contents for 7502860
Page 95: ...95 5794 780 GB ...