Viessmann VITODENS 242-F Installation And Service Instructions Manual page 141

Repair
(cont.)
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Sensor type: NTC 10 kΩ
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 har-
ness 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 collector temperature sensor or cylinder tempera-
ture sensor on the solar control module
The solar control module is attached to
the l.h. side of the air box.
2. Check the sensor resistance and
compare it with the curve.
3. In the case of severe deviation,
replace the sensor.
Danger
The boiler water temperature
sensor is immersed in the
heating water (risk of scald-
ing).
Drain the boiler on the heating
water side before replacing
the sensor.
Troubleshooting
141