Viessmann B0KA - Page 59

59
Displayed fault
code
System characteristics Cause Measures
62 Burner in a fault state High limit safety cut-out
has responded.
■
Check heating system fill level.
■
Check pre-charge pressure in di-
aphragm expansion vessel. Ad-
just to required system pressure.
■
Check whether flow rate is suffi-
cient (circulation pump).
■
Check function of 3-way diverter
valve. Vent the system.
Reset the appliance.
63 Burner in a fault state Flue gas temperature lim-
iter has responded.
■
Check heating system fill level.
■
Check pre-charge pressure in di-
aphragm expansion vessel. Ad-
just to required system pressure.
■
Check whether flow rate is suffi-
cient (circulation pump).
■
Check function of 3-way diverter
valve.
Vent the system.
Reset the appliance once the flue
system has cooled down.
64 Normal operation; burner re-
starts.
Flame loss in the stabilisa-
tion or operating phase.
■
Check gas supply (gas pressure
and gas flow switch).
■
Check balanced flue system for
flue gas recirculation.
■
Check ionisation electrode (re-
place if necessary): Check the
distance of the electrode to the
burner gauze assembly and its
contamination level.
67 Burner in a fault state Ionisation current lies out-
side the permissible range
Check gas supply (gas pressure
and gas flow switch), check gas
solenoid valve and inlet strainer.
Check ionisation electrode for the
following:
■
Clearance to burner gauze as-
sembly
■
Check electrode/burner gauze
assembly for contamination.
If specified measures do not help,
replace fan unit.
Reset the appliance.
68 Burner in a fault state Flame signal is already
present at burner start.
Close the gas shut-off valve. Re-
move connecting cable of the ioni-
sation electrode. Reset the appli-
ance.
If the fault persists, replace the
HBMU heat management unit. See
chapter "Replacing the HBMU heat
management unit".
Troubleshooting
Fault messages (cont.)
6179762
Diagnosis