Viessmann B0KA Installation And Service Instructions Manual page 59

Fault messages
(cont.)
Displayed fault System characteristics
code
62 Burner in a fault state
63 Burner in a fault state
67 Burner in a fault state
68 Burner in a fault state
Cause
High limit safety cut-out
has responded.
Flue gas temperature lim-
iter has responded.
Ionisation current lies out-
side the permissible range
Flame signal is already
present at burner start.
Troubleshooting
Measures
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.
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.
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 the electrode/burner
■
gauze assembly for dirt.
If specified measures don't help,
replace fan unit.
Reset the appliance.
Close gas shut-off valve. Remove
connecting cable of the ionisation
electrode. Reset the appliance.
If the fault persists, replace the
HBMU heat management unit. See
chapter "Replacing the HBMU heat
management unit".
59