Viessmann VITODENS 100-W Installation And Service Instructions Manual page 44

Troubleshooting
Repairs
(cont.)
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Checking cylinder temperature sensor (gas condensing boiler)
X21 X21 X7 X7
X20 X20
5 5
44
2. Check the sensor resistance and
compare it with the curve.
3. In the case of severe deviation, drain
the boiler on the heating water side
and replace the sensor.
Danger
The boiler water temperature
sensor is immersed in the
heating water (risk of scald-
ing).
Drain the boiler before replac-
ing the sensor.
1. Remove plugs % from the cable har-
ness and check the resistance.