Viessmann VITODENS 200-W Service Instructions Manual page 84

Troubleshooting
Repairs
(cont.)
Checking the temperature limiter
Check the temperature limiter, if the burner control unit cannot be reset after a
fault shutdown, although the boiler water temperature is below approx. 75 °C.
84
1. Boiler water temperature sensor:
Pull the leads from boiler water
temperature sensor A and
check the resistance.
Cylinder temperature sensor: Pull
plug % from the cable harness at
the control unit and check the
resistance.
Flow temperature sensor: Pull
plug "X3" from the control unit
and check the resistance across
terminals "X3.4" and "X3.5".
2. Check the sensor resistance and
compare the actual values with the
curve.
3. Replace the sensor in case of
severe deviation.
Danger
The boiler water tempera-
ture sensor is immersed in
the heating water (risk of
scalding).
Drain the boiler before repla-
cing the sensor.