Viessmann VITODENS 200-W Installation And Service Instructions For Contractors page 100

Troubleshooting
Fault messages
(cont.)
Displayed fault System characteristics
code
F.464 Burner in a fault state
F.467 Burner in a fault state
100
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.
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 flue system. Remove flue
■
gas recirculation if required.
Check system for condensate
■
backup.
Reset the appliance.
Note
To prevent water damage, detach
fan unit before removing the burn-
er.
If fault permanently persists, re-
place BCU burner control unit (see
page 109).
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 strainer on the in-
let side 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.