Viessmann VITODENS 333 Service Instructions Manual page 87

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. The lockout can be reset no sooner than after 20
minutes by pressing reset E.
Note
The equipment will also be locked out again for 20 minutes if the mains power
supply is switched OFF.
3. Replace the sensor in case of
severe deviation.
Danger
The loading temperature
sensor is immersed in the
heating water (risk of scald-
ing).
Drain the boiler before repla-
cing the sensor.
Troubleshooting
87