Viessmann B2HF - Fault messages

87
Note
For diagnosis and troubleshooting, see chapter
"Repairs".
Fault messages are dependent on appliance equip-
ment level.
Displayed fault
code
System characteristics Cause Measures
F.5 Flow rate not being moni-
tored. System continues op-
erating in normal mode with
replacement value.
Lead break or short cir-
cuit, flow sensor
Check plug 33/X6 and cable be-
tween BCU burner control unit and
flow sensor:
■
Check voltage level, to see if 5 V
present at plug 33, pin 1 and 2.
■
Turn the gas condensing boiler
ON/OFF switch off and back on
again.
F.7 No DHW heating Lead break, cylinder tem-
perature sensor
■
Check DHW setting in the com-
missioning assistant and correct
if required.
■
Check cylinder temperature sen-
sor (plug 5, wires 3 and 4).
■
Measure voltage at sensor input
on electronics module. Set value:
3.3 V– with sensor disconnected.
Replace faulty component if re-
quired.
F.8 No DHW heating Short circuit, cylinder tem-
perature sensor
Check cylinder temperature sensor
(plug 5, wires 3 and 4).
Replace faulty component if re-
quired.
F.9 No DHW heating Lead break, outlet/flow
sensor
Check cable between BCU and
sensor.
F.10 No DHW heating Short circuit, outlet/flow
sensor
Check cable between BCU and
sensor.
F.11 No solar DHW heating or
central heating backup
Lead break, collector tem-
perature sensor
■
Check collector temperature sen-
sor.
■
Measure voltage at sensor input
on electronics module. Set value:
3.3 V– with sensor disconnected.
F.12 No solar DHW heating Short circuit, collector
temperature sensor
■
Check collector temperature sen-
sor.
■
Measure voltage at sensor input
on electronics module. Set value:
3.3 V– with sensor disconnected.
F.13 Regulates as if the outside
temperature were 0 °C.
Lead break, outside tem-
perature sensor
■
Check operating mode setting in
commissioning assistant and
remedy if required.
■
Check outside temperature sen-
sor.
■
Measure voltage at sensor input
on electronics module. Set value:
3.3 V– with sensor disconnected.
Replace faulty component if re-
quired.
F.14 Regulates as if the outside
temperature were 0 °C.
Short circuit, outside tem-
perature sensor
Check outside temperature sensor.
Troubleshooting
Fault messages
5593201
Diagnosis