Viessmann Vitotwin 300-W Installation And Service Instructions For Contractors page 127

Fault messages
Fault mes- Cause
sage
"260: Flow Short circuit or lead break to
sensor 3" flow temperature sensor,
heating circuit 3.
"261: Loss After 5 attempts to start the
of flame Eng Stirling burner, the burner
bu" control unit cannot detect a
flame.
"262: Loss
of fl'Supp
bu"
"263: Eng bu Internal communication fault
BCU failure" in Stirling burner.
"264: Supp Internal communication fault
bu BCU fail- in auxiliary burner.
ure"
"265: BCU Internal communication fault. Carry out a service reset and
failure"
"266: Fan Fan speed differs from set
fault" value.
"267: Fan Test speed not reached after
calib fault" switching on.
"268: Spool Faulty air distribution valve
valve fault" feedback.
"269: Spool
valve calib"
(cont.)
Remedy
Check flow temperature sen-
sor (see page 146)
Check the gas supply. Check
gas type setting (see
page 66).
Check electrodes (see
page 73).
Check function of gas train
and ignition transformer.
Check balanced flue system.
Ensure that flue gases are
not being recirculated.
Switch mains power off and
on again. Carry out a restart.
If the fault has not been rec-
tified, replace the control unit
PCB (see page 138).
restart. If the fault has not
been rectified, replace the
control unit PCB (see
page 138).
Check fan power cable.
Check fan for ease of opera-
tion. Replace fan if necessa-
ry.
Check plug-in connection.
Remove air distribution valve
and check for blockage or
stiffness. If the valve moves
freely, replace the motor. If
the valve is stiff, replace the
valve.
Troubleshooting
Re-
set-
ting
UR
AR
SR
SR
SR
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