Viessmann B2TF - Page 81

81
Displayed fault
code
System characteristics Cause Measures
F.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 (flow sensor and circulation
pump).
■
Check 3-way diverter valve func-
tion in actuator test. Vent the sys-
tem.
Reset the appliance.
F.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 (flow sensor and circulation
pump).
■
Check 3-way diverter valve func-
tion in actuator test.
Vent the system.
Reset the appliance once the flue
system has cooled down.
F.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 don't help,
replace fan unit.
Reset the appliance.
F.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 BCU
burner control unit: See page 100.
Troubleshooting
Fault messages (cont.)
6151778
Service