Viessmann VITOCAL 300 Installation And Service Instructions Manual page 59

Control unit diagnostics
Skipping fault messages
To enable adjustments/scans at the
control unit:
1. Open the programming unit flap. All
current fault messages will be dis-
played.
Displaying fault messages
Fault messages
System fault
10 Outside tempera-
ture sensor
18 Outside tempera-
ture sensor
20 Sec. flow sensor
28 Sec. flow sensor
30 Primary in sen-
sor
31 Primary out sen-
sor
38 Primary in sen-
sor
39 Primary out sen-
sor
40 Flow sensor
HC 2
42 External HS
44 Flow sensor NC
45 Room tempera-
ture sensor NC
(cont.)
2. Press "BACK".
The main menu will be displayed.
You can now make adjustments
and scans.
Cause
Control unit processor
faulty
Short circuit
Lead broken
Short circuit
Lead broken
Short circuit
Lead broken
Short circuit
External heat source
faulty
Short circuit
Troubleshooting
Measures
Replace programming unit
Check the sensor; replace if
required
Check the terminals; replace
the sensor, if required
Check the sensor; replace if
required
Check the terminals; replace
the sensor, if required
Check the sensor; replace if
required
Check the terminals; replace
the sensor, if required
Check the sensor; replace if
required
Check external heat source
Check the sensor; replace if
required
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