Viessmann B2TF Installation And Service Instructions Manual page 84

Gas condensing storage combi boiler with 7 inch colour touchscreen
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Troubleshooting
Fault messages
(cont.)
Displayed fault
System characteristics
code
F.163
Burner in a fault state
F.182
No DHW heating
F.183
No DHW heating
F.184
Burner in a fault state
F.185
Burner in a fault state
F.299
Time/date incorrect
F.342
No central heating, no DHW
heating
F.345
Burner locked out, automatic
enabling after appliance cool-
down. Independent restart.
84
Cause
Memory access checksum
error BCU
Short circuit, outlet tem-
perature sensor (if instal-
led)
Lead break, outlet temper-
ature sensor (if installed)
Short circuit, flow temper-
ature sensor/high limit
safety cut-out
Lead break, flow tempera-
ture sensor/high limit safe-
ty cut-out
Real time clock setting in-
correct
Communication error,
burner control unit BCU
Temperature limiter has
responded.
See heat generator speci-
fication.
Measures
Reset the appliance.
If fault recurs, replace BCU burner
control unit: See page 100.
Check outlet temperature sensor
(plug X1, cores 13 and 14). Meas-
ure sensor input on electronics
module. Set value: 3.3 V
sensor disconnected
Check outlet temperature sensor
(plug X1, cores 13 and 14).
Check the flow temperature sen-
sor/high limit safety cut-out.
Check sensor lead. Replace faulty
component if required.
Reset the appliance.
Check the flow temperature sen-
sor/high limit safety cut-out. Re-
place faulty component if required.
Reset the appliance.
Set the time and date.
Check connecting cable to the
burner control unit plug X4 on
BCU.
Check all plug-in connections
and cables of the internal CAN.
Remove all plugs except X4, X2,
X16 and X18 from the BCU burn-
er control unit. Check whether
fault persists.
Note
Several other fault messages will
be added due to the removed
plugs. Ignore these. If fault mes-
sage F.342 is no longer shown, re-
insert the plugs one by one and es-
tablish which component is faulty.
Reset the appliance.
Ensure adequate heat transfer.
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 pump).
Check 3-way diverter valve func-
tion in actuator test. Vent the sys-
tem.
If the fault occurs during DHW
heating: Check DHW cylinder or
plate heat exchanger for contami-
nation and scaling.
with

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