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134
Control unit
message
System characteristics
Cause
Measures
F.524/18F1
No power generation
Fault, reformer burner ig-
nition
Reset the fault once.
If the fault recurs, notify Viessmann
Technical Service.
F.527
Burner locked out
Update parameters faulty
or incomplete
Repeat burner control unit flash
operation.
F.528
Burner locked out
Basic programming faulty
or incomplete
Repeat burner control unit flash
operation.
F.540
Burner in a fault state
Condensation water accu-
mulation in the heat cell
Check if condensate banked.
Check condensate drain and trap.
Note
To prevent water damage, detach
fan unit before removing the burn-
er.
Reset device.
F.542
Mixer closes. Heating circuit
pump is operational.
Lead break, flow tempera-
ture sensor, heating circuit
1 with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
F.543
Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor 1 in heating
circuit with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
F.544
Mixer closes. Heating circuit
pump is operational.
Lead break, flow tempera-
ture sensor, heating circuit
2 with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
F.545
Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor 2 in heating
circuit with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
F.546
Mixer closes. Heating circuit
pump is operational.
Lead break, flow tempera-
ture sensor, heating circuit
3 with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
F.547
Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor 3 in heating
circuit with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
F.548
Mixer closes. Heating circuit
pump is operational.
Lead break, flow tempera-
ture sensor, heating circuit
4 with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
F.549
Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor 4 in heating
circuit with mixer
Check flow temperature sensor
TS1 on extension kit mixer (elec-
tronics module ADIO). See
page 140.
Note
If subscriber faults occur,
"Error, subscriber ..."
is dis-
played.
Troubleshooting
Fault messages on the gas condensing…
(cont.)
5853335
Diagnosis