Checking The Boiler Water Temperature Sensors, Cylinder Tempera- Ture Sensor Or Flow Temperature Sensor For The Low Loss Header; Checking The Flue Gas Temperature Sensor - Viessmann VITODENS 200-W Installation And Service Instructions Manual

Maintenance
(cont.)
Checking the boiler water temperature sensors, cylinder temperature sensor or flow tempera-
ture sensor for the low loss header
1. ■ Boiler water temperature sensor 1
Pull the leads from boiler water temperature sen-
sor A and check the resistance.
§
■ Boiler water temperature sensor 2
Pull the leads from boiler water temperature sen-
sor B 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".

Checking the flue gas temperature sensor

The flue gas temperature sensor locks out the boiler
when the permissible flue gas temperature is excee-
ded. Reset the interlock after the flue system has
cooled down by pressing reset button R.
Fig.51
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Fig. 52 Sensor type: NTC 10 k
Fault during commissioning (fault A3)
During commissioning, the control unit checks correct
placement of the flue gas temperature sensor. If com-
missioning is terminated and fault message A3 is dis-
played:
A
Ω
2. Check the sensor resistance and compare it with
the curve.
3. In the event of severe deviation replace the sensor.
Danger
The boiler water temperature sensor is in
direct contact with the heating water (risk of
scalding).
Drain the boiler before replacing the sensor.
1. Pull leads from flue gas temperature sensor
2. Check the sensor resistance and compare it with
the curve.
3. In the event of severe deviation replace the sensor.
1. Check whether the flue gas temperature sensor is
correctly inserted. See previous diagram.
2. If necessary, correct the position of the flue gas
temperature sensor or replace faulty flue gas tem-
perature sensor.
Troubleshooting
.
A
91