Checking The Boiler Temperature Sensor, Cylinder Temperature Sensor Or Low Loss Header Flow Temperature Sensor - Viessmann Vitodens 200-W Installation And Service Instructions For Contractors

Troubleshooting
Repair
(cont.)
Checking the boiler temperature sensor, cylinder temperature sensor or low loss header flow
temperature sensor
A
%
X3
Fig. 46
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Fig. 47 Sensor type: NTC 10 k
1. Boiler water temperature sensor
■
Pull the leads from boiler water temperature sen-
sor and check the resistance.
A
Cylinder temperature sensor
■
Pull plug from the cable harness at the control
%
unit and check the resistance.
Low loss header flow temperature sensor
■
Pull plug "X3" from the control unit and check the
resistance across terminals "X3.4" and "X3.5".
84
Ω
2. Check the sensor resistance and compare it with
the curve.
3. Replace the sensor in the case of severe deviation.
Danger
The boiler water temperature sensor is
immersed in the heating water (risk of scald-
ing).
Drain the boiler on the heating water side
before replacing the sensor.