Checking The Flue Gas Temperature Sensor - Viessmann Vitodens 242-F Installation And Service Instructions Manual

Troubleshooting
Maintenance
(cont.)
Fig. 74
1. Shut off and drain the boiler on the heating water
and DHW sides.
2. Release side fasteners and pivot control unit for-
ward.
3. Remove the siphon (see page 42).
4. Push thermal insulation panel
remove.

Checking the flue gas temperature sensor

The flue gas temperature sensor locks the boiler if the
permissible flue gas temperature is exceeded. After
the flue system has cooled down, press the reset but-
ton R to cancel the lock.
106
B A
5. Undo two screws
6. Check the connections on the heating water and
7. Install in reverse order using new gaskets.
upwards and
A
C
and remove plate heat
B
exchanger C with insulation through the front.
DHW side for contamination and scaling; if
required, replace the plate heat exchanger.