Viessmann FB2B Installation And Service Instructions Manual page 121

Repairs
(cont.)
Checking the flue gas temperature sensor
The flue gas temperature sensor locks out the boiler when the permissible flue gas
temperature is exceeded. Reset the interlock after the flue system has cooled down
by pressing reset button R.
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
1. Pull the leads from flue gas tempera-
ture sensor A.
2. Check the sensor resistance and
compare it with the curve.
3. Replace the sensor in case of severe
deviation.
Troubleshooting
121