Viessmann Vitoladens 300-W Service Instructions For Contractors page 72

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 the flue gas temperature sensor
The flue gas temperature sensor locks out the boiler when the permissible flue gas
temperature is exceeded. Reset interlock after flue gas system has cooled down by
pressing reset button "E".
A
72
2. Check the sensor resistance and
compare the actual values with the
curve.
3. Replace the sensor in case of severe
deviation.
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. Pull the leads from flue gas tempera-
ture sensor A.
2. Check the sensor resistance and
compare it with the curve.