Checking The Boiler Temperature Sensor And Fixed High Limit, Dhw Tank Temperature Sensor Or Flow Temperature Sensor For The Low Loss Header; Check The Flue Gas Temperature Sensor - Viessmann VITODENS 200-W Service Instructions Manual

Vitodens 200-W B2HA 112, 150 Service
Corrective Action
(continued)
Checking the boiler temperature sensor and fixed high
limit, DHW tank temperature sensor or flow temperature
sensor for the low loss header
1. Boiler temperature sensor:
Remove lead to boiler water temperature sensor §
or §A and check the resistance.
DHW Tank temperature sensor:
Pull plug % from the cable harness at the control
unit and check the resistance.
Supply temperature sensor or Low-loss header
temperature sensor ?:
Pull plug "X3" from the control unit and check the
resistance across terminals "X3.4" and "X3.5".
Note: Only one temperature sensor ? may be used.
2. Check the sensor resistance and compare the actual
values with the curve.
3. Replace the sensor in the case of severe deviation.
Sensor type: NTC 10 kΩ
WARNING
The boiler water temperature sensors are immersed in
the heating water (risk of scalding). Drain the boiler
before replacing the sensor.

Check the flue gas temperature sensor

The flue gas temperature sensor locks out the boiler when
the permissible flue gas temperature is exceeded. Reset
the interlock after the flue system has cooled down by
pressing reset button R.
1. Pull leads from flue gas temperature sensor A.
2. Check the sensor resistance and compare it with the
curve.
3. Replace the sensor in the case of severe deviation.
Sensor type: NTC 10 kΩ
Temperature sensors
Troubleshooting
81