Viessmann Vitocrossal 300 Service Instructions For Contractors page 101

Fault codes
(cont.)
Displayed System characteris-
fault code tics
E7 Burner in a fault
state
E8 Burner in a fault
state
EA Burner in a fault
state
Cause
Ionisation current
too low during cali-
bration
The ionisation cur-
rent lies outside the
permissible range
Ionisation current
outside permissi-
ble range during
calibration (devia-
tion from previous
level too great)
Troubleshooting
Measures
Check ionisation elec-
trode:
■ Distance to burner
gauze assembly (see
page 21)
■ Contamination of elec-
trode
■ Connecting lead and
plug-in connections
Check flue system; rem-
edy flue gas recirculation
if required.
Press reset button R
Check gas supply (gas
pressure and gas flow lim-
iter), gas train and con-
necting lead.
Check allocation of gas
type (see page 12).
Check ionisation elec-
trode:
■ Distance to burner
gauze assembly (see
page 21)
■ Contamination of elec-
trode
Press reset button R
Check flue system; rem-
edy flue gas recirculation
if required.
In open flue mode, pre-
vent very dusty conditions
for the combustion air.
Press reset button R.
Following several unsuc-
cessful reset attempts,
replace boiler coding card
and press reset button R.
101