Viessmann B1HE-199 - Page 78

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Vitodens 100-W, B1HE/B1KE Combi Installation/Service
Fault Messages
(continued)
Troubleshooting
Displayed
fault code
System characteristics Cause Measures
F.377 Burner in a fault state Post-processing of
ionization adjustment:
Stabilization conditions
for post calibration
not met
Check gas type setting. If fault recurs, replace BCU
burner control unit: See page 89.
Reset the boiler.
F.378 Burner in a fault state Flame loss during
stabilization or
operating phase
 Check gas supply (gas pressure and gas flow switch).
 Check flue gas recirculation.
 Check for contamination of ionization electrode and
flame body assembly.
Reset the boiler.
F.379 Burner in a fault state Flame signal not
present or insufficient
 Check ionization electrode connecting cable for
damage and firm seating.
 Check ionization electrode; replace if necessary.
Reset the boiler.
F.380 Burner in a fault state Flame loss
immediately after
flame formation
(during safety time)
Check gas supply (gas pressure and gas flow switch).
Check balanced flue system for flue gas recirculation.
Check ionization electrode and flame body assembly:
 Clearance to flame body assembly
 Contamination on electrode
Reset the boiler.
F.381 Burner in a fault state Flame loss during
operating phase
Check gas supply (gas pressure and gas flow switch).
Check balanced flue system for flue gas recirculation.
Check ionization electrode and flame body assembly:
 Clearance to flame body assembly.
 Contamination on electrode
Reset the boiler.
F.382 Burner in a fault state Error counter has
exceeded limit.
Reset the boiler.
Work through fault analysis using fault history.
F.383,
F.384
Burner in a fault state Possible contamination
of gas line
 Check gas line for contamination.
 Check the gas supply pressure.
 Replace gas fan if necessary.
Reset the boiler.
F.385 Burner in a fault state Short circuit, signal
1, ionization current.
BCU burner control
unit faulty.
Check ionization electrode and connecting cable.
If fault persists, replace BCU burner control unit:
See page 89.
Reset the boiler.
F.386 Burner in a fault state BCU burner control
unit faulty
Replace BCU burner control unit:
See page 89.
Reset the boiler.
F.387 Burner in a fault state Ground fault,
ionization current.
BCU burner control
unit faulty.
1. Check system for condensate backup.
 Check the condensate drain and siphon trap.
 Replace insulation blocks, electrodes and flame
body assembly if necessary.
Note: To prevent water damage, detach fan unit
before removing the burner. Protect electronic
components from escaping condensate.
If there is no condensate backup, take the following
steps:
2. Check ionization electrode and connecting cable.
If fault persists, replace BCU burner control unit:
See page 89.
Reset the boiler.
F.388 Burner in a fault state BCU burner control
unit faulty
Replace BCU burner control unit:
See page 89.
Reset the boiler.