Troubleshooting; Diagnosis - Viessmann MatriX Service Instructions Manual

Diagnosis

Faults with fault indication on the display and programming unit
Message codes
Message System characteris-
code tics
A Burner not working
A Burner not working
F Burner in fault state
L Air pressure switch
responds during
operation
P System not working
General process errors
Fault code System characteris-
tics
20 Fan pressure is pro-
duced during the air
pressure switch idle
state check
20 Air pressure switch
contact not in idle
state
21 Air pressure switch
shows no air pres-
sure; fan not running
21 Fan not running
22 Gas pressure switch
signals no gas pres-
sure during the safety
time
Cause
Gas pressure
switch fault
Lack of gas
See fault code
Flue gas back
pressure, conden-
sate banked up
Incorrect parame-
ter set program-
med
Cause
Wind influence on
fan
Air pressure switch
faulty
Air pressure switch
faulty
Fan faulty; cables
faulty or broken
Gas shut-off valve
closed; gas pres-
sure switch faulty

Troubleshooting

Measures
Check gas pressure
switch
Notify gas supply utility
See fault code steps
Check condensate drain,
remove flue gas back
pressure, reset burner
control unit in accordance
with details on page 22.
See acknowledging a
parameter set, page 25
Measures
Check flue gas draught
(chimney)
Replace air pressure
switch
Replace air pressure
switch
Check cables and replace
fan if required
Open gas shut-off valve,
check gas supply pres-
sure and clean gas filter if
required
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