Unit installation

40
Faults with fault indicator on the display and programming unit
Message codes
Message
code
System characteris-
tics
Cause Measures
A Burner off Gas pressure
switch fault
Check the gas pressure
switch
A Burner off Lack of gas Notify your gas supply util-
ity
F Burner is in a fault
state
See fault code See fault code steps
L Air pressure switch
switches off during
operation
Flue gas back
pressure, conden-
sate banked up
Check condensate drain,
remove flue gas back
pressure, reset the burner
control unit in accordance
with the details on
page 32 .
P System off Incorrect parame-
ter set selected
See acknowledging a
parameter set, page 37.
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 the flue draught
(chimney)
20 Air pressure switch
contact is not in the
idle state
Air pressure switch
faulty
Replace the air pressure
switch
21 Air pressure switch
shows no air pres-
sure, fan not running
Air pressure switch
faulty
Replace the air pressure
switch
21 Fan does not run Fan faulty; cables
are faulty or bro-
ken
Check cables and replace
the fan if required
22 The gas pressure
switch signals no gas
pressure during the
safety time
Gas shut-off valve
closed, gas pres-
sure switch faulty
Open the gas shut-off
valve and check the gas
flow pressure; clean the
gas filter if required
Troubleshooting
Diagnosis
5692 907 GB