Viessmann 47-819-55 - Page 64

64
8
System characteristics
No DHW heating
Cause
Short circuit, cylinder temperature sensor
Measures
Check the cylinder temperature sensor (terminal
S.T.S).
Replace faulty component if necessary.
13
System characteristics
Regulates as if the outside temperature were 0 °C.
Cause
Lead break, outside temperature sensor
Measures
■
Check operating mode setting in commissioning
assistant and remedy if necessary.
■
Check the outside temperature sensor and connec-
tion to sensor (terminal O.T.S).
■
Measure the voltage at the sensor input on the
HBMU heat management unit. Set value: 3.3 V with
sensor disconnected
Replace faulty component if necessary.
14
System characteristics
Regulates as if the outside temperature were 0 °C.
Cause
Short circuit, outside temperature sensor
Measures
Check the outside temperature sensor and connection
to sensor (terminal O.T.S). Replace faulty components
if necessary.
49
System characteristics
Burner in a fault state
Cause
Lead break, flue gas temperature sensor
Measures
Check flue gas temperature sensor.
Reset the appliance.
50
System characteristics
Burner in a fault state
Cause
Short circuit, flue gas temperature sensor
Measures
Check flue gas temperature sensor.
Reset the appliance.
Troubleshooting
Fault messages (cont.)
6221465
Diagnosis