Repairs; Checking The Outside Temperature Sensor; Checking The Boiler Water Temperature Sensor Or Cylinder Temperature Sensor - Viessmann Vitoladens 300-C Installation And Service Instructions Manual

Repairs

Checking the outside temperature sensor

X3
Fig. 56
1. Disconnect plug "X3" from the control unit.

Checking the boiler water temperature sensor or cylinder temperature sensor

5
Fig. 58
2. Test the resistance of the outside temperature sen-
sor across terminals "X3.1" and "X3.2" on the dis-
connected plug and compare it with the curve.
200
100
80
60
40
20
10
8
6
-20 -10 0 10 20
Temperature in °C
Fig. 57 Sensor type: NTC 10 k
3. In the event of severe deviation from the curve,
disconnect the wires at the sensor and repeat the
test on the sensor itself.
4. Depending on the test result, replace the lead or
the outside temperature sensor.
1. Boiler water temperature sensor: Disconnect
■
leads from boiler water temperature sensor
and check the resistance.
■ Cylinder temperature sensor: Disconnect plug
from the cable harness at the control unit and
check the resistance.
2. Check the sensor resistance and compare it with
the curve.
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Fig. 59 Sensor type: NTC 10 k
Troubleshooting
30
Ω
A
%
Ω
85