Viessmann Vitodens 100-W B1HA 26Vitodens 100-W B1HA 35Vitodens 100-W B1KA 35 Installation And Service Instructions Manual page 61

Vitodens 100-W, B1HA series & B1KA Combi Installation/Service
Boiler Connection
(continued)
Check fixed high limit
If the burner control unit cannot be reset after a fault
shutdown ( ), even though the boiler water temperature
F2
is below approx. 203°F (95°C), check the fixed high limit.
1. Pull the leads from fixed high limit A.
2. Check the continuity of the fixed high limit with
a multimeter.
3. Remove faulty fixed high limit.
4. Coat the replacement fixed high limit with heat
conducting paste and install.
5. To reset, refer to page 76.
Check flue gas temperature sensor
1. Pull the leads from flue gas temperature sensor A.
2. Check the sensor resistance and compare it with the
curve.
3. Replace the sensor in case of severe deviation.
Temperature
Troubleshooting
61