Internal System Faults - Viessmann MatriX Service Instructions For Contractors

Troubleshooting
Fault codes
(cont.)
Displayed fault System characteristics
code
F F5 Air pressure switch switches
off during operation
F F6 Gas pressure switch reports
no gas pressure.
F F7 Fan pressure is produced
during the air pressure switch
idle state check.
F F7 Air pressure switch contact is
not in the idle state
F F8 Flame tears off during opera-
tion.
F F8 Flame tears off during opera-
tion.
F F9 Fan not running; fan speed
not reached.
F F9 Status duration too long, fan
ramp-up
F F9 Fan speed deviation
F F9 No feedback from fan
F FA Fan runs without demand;
burner control unit in a fault
state.
F Fb Burner does not start.

Internal system faults

Internal system faults occur if a flawless program
sequence can no longer be guaranteed.
38
Cause
Flue gas back pressure;
condensate banked up; air
pressure switch hose faul-
ty; connecting hose leak-
ing
Gas shut-off valve closed;
gas pressure switch faulty;
multiple problems with gas
supply
Wind influence on fan
Air pressure switch faulty
Burner gauze assembly
faulty
Combustion characteris-
tics not ideal
Fan faulty; cables are faul-
ty or broken
Internal fault; fan cannot
reach its set value.
Fan faulty, cable " A"
a-Ö
faulty or broken. Check
cable " A", check exter-
a-Ö
nal power supply, replace
cable or fan, remove for-
eign bodies.
Fan faulty, external fan
power supply not connec-
ted or faulty, cable " a-Ö A"
faulty or broken, fan
blocked (poss. by foreign
bodies)
Fan does not reach idle
state, cable " A" faulty,
a-Ö
fan faulty, burner control
unit faulty
Excessive combustion
chamber pressure
(LDW2); condensate
backup or condensate
path blocked off
Measures
Remove flue gas back pressure;
check if condensate banked up; re-
set burner control unit; replace
hose.
Open gas shut-off valve; check gas
flow pressure; replace gas filter if
necessary; reset burner control
unit; replace gas train.
Check the flue draught (chimney).
Replace air pressure switch.
Check burner gauze assembly; re-
place if damaged.
Adjust burner setting.
Check cables and replace fan if
necessary.
Replace fan or burner control unit.
Check cable; replace cable "
or fan if necessary.
Check cable " A", check exter-
a-Ö
nal power supply, replace cable or
fan, remove foreign body.
Fan subject to wind influence,
check flue outlet and fan, replace
cable " A", replace fan, replace
a-Ö
burner control unit.
Check condensate drain and flue
gas path for blockages.
A"
a-Ö