29
Faults with fault indication on the display and programming unit
Message codes
Message
code
System characteris-
tics
Cause
Measures
A
Burner not working
Gas pressure
switch fault
Check gas pressure
switch
A
Burner not working
Lack of gas
Notify gas supply utility
F
Burner in fault state
See fault code
See fault code steps
L
Air pressure switch
responds during
operation
Flue gas back
pressure, conden-
sate banked up
Check condensate drain,
remove flue gas back
pressure, reset burner
control unit in accordance
with details on page 22.
P
System not working
Incorrect parame-
ter set program-
med
See acknowledging a
parameter set, page 25
General process errors
Fault code System characteris-
tics
Cause
Measures
20
Fan pressure is pro-
duced during the air
pressure switch idle
state check
Wind influence on
fan
Check flue gas draught
(chimney)
20
Air pressure switch
contact not in idle
state
Air pressure switch
faulty
Replace air pressure
switch
21
Air pressure switch
shows no air pres-
sure; fan not running
Air pressure switch
faulty
Replace air pressure
switch
21
Fan not running
Fan faulty; cables
faulty or broken
Check cables and replace
fan if required
22
Gas pressure switch
signals no gas pres-
sure during the safety
time
Gas shut-off valve
closed; gas pres-
sure switch faulty
Open gas shut-off valve,
check gas supply pres-
sure and clean gas filter if
required
Troubleshooting
Diagnosis
5692 488 GB