Viessmann B2TF - Further Messages; Service Messages; Status Messages; Warning Messages

95
Displayed fault
code
System characteristics Cause Measures
F.548 Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor for heating
circuit 4 with mixer
■
Check flow temperature sensor,
mixer 4.
■
Measure voltage at sensor input
on electronics module. Set value:
3.3 V– with sensor disconnected
■
Check commissioning assistant
setting.
■
Checking setting of ADIO rotary
switch.
F.549 Mixer closes. Heating circuit
pump is operational.
Short circuit, flow temper-
ature sensor for heating
circuit 4 with mixer
Check flow temperature sensor,
mixer 4.
Measure voltage at sensor input on
electronics module. Set value:
3.3 V
–
with sensor disconnected
Note
If subscriber faults occur, "Fault, subscriber ..." is dis-
played.
Further messages
Service messages
Message on the display Meaning
P.1 Service due after interval.
P.4 Top up heating water.
P.8 Service due after burner hours run.
Status messages
Message on the display Meaning
S.60 Summer mode active (outside temperature economy function)
S.74 Heating suppression, heating
S.75 DHW circulation pump active
S.94 No demand, external hook-up, heating circuit 1
S.95 No demand, external hook-up, heating circuit 2
S.96 No demand, external hook-up, heating circuit 3
Warning messages
Messages on the
display
Meaning Measure
A.11 System pressure has fallen below normal
limit.
Check system pressure and diaphragm ex-
pansion vessel.
Check settings for set system pressure and
range in the commissioning assistant.
A.12 Real time clock battery flat. Replace the battery (type CR2032) in the
HMU heat management unit.
A.18 Possible condensate backup in the heat
cell
Check combustion chamber and conden-
sate drain.
Troubleshooting
Fault messages (cont.)
6151778
Service