Viessmann B0KA - Page 77

77
Cylinder temperature sensor/outlet temperature
sensor
1. Check lead and plug of the cylinder temperature
sensor or outlet temperature sensor.
2. Disconnect wires 3 and 4 from terminal S.T.S.
3. Check the sensor resistance. Compare the resist-
ance with the value for the current temperature
from the following diagram.
In the event of severe deviation (> 10 %), replace
the sensor.
Outside temperature sensor
1. Check the lead and plug of the outside tempera-
ture sensor.
2. Disconnect wires 3 and 4 from terminal O.T.S.
3. Check the sensor resistance. Compare the resist-
ance with the value for the current temperature
from the following diagram.
If the results are very different from the curve
(> 10 %), disconnect the wires from the sensor.
Repeat the test directly on the sensor.
Check the on-site lead. 2-core lead, up to 35 m
long with 1.5 mm
2
cross-section
Depending on the test result, replace the lead or
the outside temperature sensor.
Flue gas temperature sensor
1. Check the lead and plug of flue gas temperature
sensor
C
.
2.
Disconnect leads, flue gas temperature sensor
C
.
3. Rotate sensor (anti-clockwise) by ¼ turn to remove
it (bayonet fitting).
4. Check the sensor resistance. Compare the resist-
ance with the value for the currently recorded tem-
perature from the following diagram.
In the event of severe deviation (> 10 %), replace
the sensor.
5. Rotate sensor (clockwise) by ¼ turn to install it.
Danger
Escaping flue gas can cause poisoning.
When restarting, check for leaks on the flue
gas side.
6.
Reconnect leads, flue gas temperature sensor
C
.
7. If the permissible flue gas temperature has been
exceeded, the flue gas temperature sensor locks
out the appliance. Reset the burner on the pro-
gramming unit once the flue system has cooled
down.
■
Flue gas temperature sensor
■
Flow temperature sensor
■
Cylinder temperature sensor
■
Outlet temperature sensor
■
Outside temperature sensor
10
1
10
Temperature in °C
0.4
0.6
0.8
2
4
6
8
Resistance in kΩ
30 50 70 90 110
20
Sensor type: NTC 10 k
Ω
100
10
-20 -10 0 10 20 30
Temperature in °C
6
8
20
40
60
80
200
Resistance in kΩ
Sensor type: NTC 10 k
Ω
Troubleshooting
Repairs (cont.)
6179762
Diagnosis