Viessmann Vitodens 050-W Installation And Service Instructions Manual page 71

Fault messages
(cont.)
Displayed fault System characteristics
code
464 Burner in a fault state
467 Burner in a fault state
Cause
Ionisation current too low
during calibration. Differ-
ential compared to previ-
ous value not plausible.
Gas supply insufficient
during calibration. Conta-
minated or insufficiently
sized gas line.
Troubleshooting
Measures
Check ionisation electrode and
■
connecting cable. Check plug-in
connections for loose contacts.
Check whether there is a lot of
■
dust in the ventilation air (e.g.
from construction work).
Check the flue system. Remove
■
flue gas recirculation if necessa-
ry.
Check system for condensate
■
backup.
Reset the appliance.
Note
To prevent water damage, detach
fan unit before removing the burn-
er.
If the fault is constant, replace the
HBMU heat management unit: See
chapter "Replacing the HBMU heat
management unit".
Note
Deposits on the electrodes indicate
foreign bodies in the combustion
air. Check the installation room and
flue system for causes of the de-
posits. For example: Laundry de-
tergents, cleaning agents, toilet-
ries, deposits in the ventilation air
supply (chimney).
If burner gauze assembly and ioni-
sation electrode have been re-
placed, also clean fan unit, gas/air
channel and Venturi extension.
Test static gas pressure and gas
■
flow pressure.
Check that on-site gas line and
■
gas flow switch are correctly
sized.
Visually inspect gas solenoid
■
valve inlet and inlet strainer for
contamination.
Reset the appliance.
Note
Contamination from a brazed gas
line, for example, can block up the
gas solenoid valve strainer on the
inlet side.
71