Viessmann 7502860, Service Instructions Manual

Page: 61 / 96

61
Displayed
fault code System characteris-
tics Cause Measures
F F4 No flame formation
during safety time;
ionisation flame mon-
itor reports no flame
signal Ignition electrodes
incorrectly adjus-
ted, electrodes
earthed, faulty igni-
tion unit, faulty
burner control unit Adjust ignition electrodes
(see page 40); replace ig-
nition unit; replace burner
control unit
F F4 No flame formation
during safety time;
ionisation flame mon-
itor reports no flame
signal Insulation body of
ignition or ionisa-
tion electrode
cracked Replace ignition or ionisa-
tion electrode
F F4 Poor start-up charac-
teristics; rotary damp-
er does not close Servomotor faulty,
servomotor con-
necting cable faul-
ty, output relay
faulty (burner con-
trol unit) Replace connecting ca-
ble; replace servomotor;
replace burner control
unit
F F4 Flame does not build
during the safety
time, no signal cap-
tured by the ionisa-
tion flame monitor Incorrect gas type
selected Select the gas type (see
from page 11)
F F4 Flame does not build
during the safety
time, no signal cap-
tured by the ionisa-
tion flame monitor Gas train does not
open Check connecting cable;
check gas train and re-
place if required
F F4 Flame does not build
during the safety
time, no signal cap-
tured by the ionisa-
tion flame monitor Combustion char-
acteristics not ide-
al Adjust the burner (see
from page 27); if necessa-
ry also adjust the setting
screws when the burner is
off to be able to start the
burner
F F5 Air pressure switch
shows no air pres-
sure, fan not running Air pressure switch
is faulty, incorrectly
connected or incor-
rectly set Replace air pressure
switch, connect correctly
or adjust
Troubleshooting
Fault codes
(cont.)
5794 780 GB