Viessmann Vitoflame 100 Service Instructions For Contractors page 29

Diagnosis
(cont.)
Fault Flash-
ing
code
red
Burner does not
start; demand indi-
cator illuminates
3 ×
10 x
Burner does not 5 ×
start and enters
fault state after ap-
5 ×
prox. 65 s
2 ×
The burner motor 3 ×
starts, but the
burner suffers a
fault shutdown
3 ×
during the pre
purge phase
3 ×
Cause
Gas supply pressure
too low; gas pressure
switch switches OFF
Burner control unit
faulty
Burner motor faulty
Servomotor faulty (no
voltage at terminal "4")
External voltage
across output term-
inals
Wind influence
The air pressure switch
contact is not in the
idle state
Earth connection at io-
nisation cable or elec-
trode
Air pressure switch
connection contami-
nated
Air pressure switch in-
correctly adjusted or
faulty
Air pressure too low
Troubleshooting
Measures
Check the gas supply
pressure. The gas flow
pressure should be at
least 20 mbar. Clean
gas filter, if required.
Replace the burner
control units
Replace burner motor
Replace the servomo-
tor
Check from where the
burner control unit re-
ceives external voltage
(e.g. via connection
"S3")
Check the chimney
draught
Check the setting of
the air pressure switch;
replace the switch, if
required
Remedy short circuit
Clean connection
Adjust the air pressure
switch (see page 17) or
replace it
Clean the impeller (see
page 19)
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