67
Displayed fault
code
System characteristics
Cause
Measures
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.
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.
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".
69
Burner in a fault state
Ionisation current lies out-
side the permissible range
Check ionisation electrode for the
following:
■
Check whether insulation block is
touching electrode ceramic.
■
To check the gas solenoid valve:
In the service menu under "b.6",
set the burner output to the lower
heating output for approx. 4 min.
If the fault occurs, replace the
HBMU heat management unit.
See chapter "Replacing the
HBMU heat management unit".
■
In the service menu under "b.6",
switch the burner output from the
lower to the upper heating out-
put. If this fault occurs during
modulation, check the intake
screen for contamination. Re-
place the fan unit if necessary.
70
Burner in a fault state
HBMU heat management
unit internal fault
Replace the HBMU heat manage-
ment unit. See chapter "Replacing
the HBMU heat management unit".
Troubleshooting
Fault messages
(cont.)
6167586
Diagnosis
