Viessmann VITODENS 343-F WS4A Installation And Service Instructions Manual page 93

Fault codes
(cont.)
Fault code System character-
on the dis- istics
play
10 Regulates as if the
outside temperature
was 0 °C
18 Regulates as if the
outside temperature
was 0 °C
20 Regulates without
flow temperature
sensor (low loss
header)
28 Regulates without
flow temperature
sensor (low loss
header)
30 Burner blocked
38 Burner blocked
40 Mixer closes.
48 Mixer closes.
50 No DHW heating
58 No DHW heating
92 Control mode
Cause Measures
Outside tempera- Check the outside tem-
ture sensor perature sensor (see
shorted out page 99).
Outside tempera- Check the outside tem-
ture sensor lead perature sensor (see
broken page 99).
System flow tem- Check the low loss
perature sensor header sensor (see
shorted out page 101).
System flow tem- Check the low loss
perature sensor header sensor (see
lead broken page 101).
Boiler water tem- Check the boiler water
perature sensor temperature sensor (see
shorted out page 101).
Boiler water tem- Check the boiler water
perature sensor temperature sensor (see
lead broken page 101).
Heating circuit Check the flow tempera-
with mixer M2 ture sensor.
flow temperature
sensor shorted
out
Heating circuit M2 Check the flow tempera-
flow temperature ture sensor.
sensor lead bro-
ken
Cylinder tempera- Check sensors (see
ture sensor page 101).
shorted out
Cylinder tempera- Check sensors (see
ture sensor lead page 101).
broken
Solar: Collector Check the sensor (see
temperature sen- page 102).
sor S1 at the
Vitosolic shorted
out
Troubleshooting
93