Viessmann Vitodens 200 Service Manual page 88

Troubleshooting
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
20 minutes later by pressing the reset button E.
Note
The equipment will also be locked out again for 20 minutes if the mains power
supply is switched OFF.
88
3. Replace the sensor in case of
severe deviation.
Note
Water can leak out when replacing
the outlet sensor. Close the cold
water shut-off valve. Drain DHW
pipe and plate heat exchanger
(secondary side).