Viessmann Vitocrossal 300 Series Service Instructions Manual page 90

Troubleshooting
Fault Codes
(continued)
Fault code on display
E4
E5
E7
E8
EA
EB
EC
ED
*1 Control mode:..............Boiler/burner fully operational (fault code must be verified and reset).
Burner in fault mode:.....Boiler control requires manual reset before burner can resume operation.
Burner blocked: ...........If fault cause is corrected, burner resumes operation.
90
System behavior*1
Burner blocked
Burner blocked
Burner in a fault mode
Burner in a fault mode
Burner in a fault mode
Burner in a fault mode
Burner in a fault mode
Burner in a fault mode
Vitocrossal 300 CU3A 26 to 199 Service
Cause
Fault, supply voltage
24V
Fault flame amplifier
Ionization current too
low during calibration
The ionization current
lies outside the
permissible range
The ionization current
lies outside the
permissible range
during calibration
(deviation from
previous level too
great)
Repeated flame loss
during calibration
Parameter fault
during calibration
Internal fault
Corrective action
Replace the control unit.
Replace control unit.
Check ionization electrode:
- Distance to burner gauze
assembly (see page 23).
- Contamination of electrode.
- Connecting lead and plug-in
connections.
Check flue system; remedy flue
gas recirculation if required.
Press reset button R.
Check gas supply (gas pressure
and gas flow limiter), gas train
and connecting lead.
Check allocation of gas type
(see page 17).
Check ionization electrode:
- Distance to burner gauze
assembly (see page 23).
- Contamination of electrode
Press reset button R.
Check flue system; remedy flue
gas recirculation if required In
open flue mode, prevent very
dusty conditions for the
combustion air.
Press reset button R. Following
several unsuccessful reset
attempts, replace boiler coding
card and press reset button R.
Check gap between ionization
electrode and burner gauze
assembly (see page 23).
Check allocation of gas type
(see page 17). Check flue
system; remedy flue gas
recirculation if required.
Press reset button R.
Press reset button R
or
Replace boiler coding card and
press reset button R.
Replace control unit.