Operating instructions

Fault code
in the dis-
play
Const. Weat-
h.
comp.
System
character-
istics
Cause Remedy
F7 X X Burner
blocked
Differential pres-
sure sensor faulty
Check the dif-
ferential pres-
sure sensor
and lead.
F8 X X Burner in
fault state
Fuel valve closes
too late
Check gas
combination
valve. Check
both control
paths.
Press E .
F9 X X Burner in
fault state
Fan speed too low
at burner start
Check the
fan, check the
fan cables
and supply,
check the fan
control.
Press E .
.
FA X X Burner in
fault state
Fan speed too hig h
at burner start
Check the
fan, check the
fan cables,
check the fan
control.
Press E .
Fd X X Burner
blocked
Burner control unit
fault
Check the
ignition elec-
trodes and
leads. Check
whether a
strong inter-
ference
(EMC) field
exists near
the equip-
ment.
Press E .
If the fault is
not remov ed,
replace the
control unit.
Checking and acknowledging faults (cont.)
82
Troubleshooting
5692 548 GB