Checking Flue Gas Temperature Sensor - Viessmann Vitoladens 300-W Installation And Service Instructions Manual

Troubleshooting
Maintenance
(cont.)
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Fig. 48 Sensor type: NTC 10 k

Checking flue gas temperature sensor

The flue gas temperature sensor locks out the boiler if
the permissible flue gas temperature is exceeded.
Reset interlock after flue system has cooled down by
pressing reset button R.
A
Fig. 49
76
Ω
1. Boiler water temperature sensor: disconnect
■
leads from boiler water temperature sensor
and check the resistance.
■ Cylinder temperature sensor: disconnect plug
from the cable harness at the control unit and
check the resistance.
■ Flow temperature sensor: disconnect plug "X3"
from the control unit and check the resistance
across terminals "X3.4" and "X3.5".
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
directly immersed in the heating water (risk
of scalding).
Drain the boiler before replacing the sensor.
1. Pull leads from flue gas temperature sensor
2. Check sensor resistance and compare it to the
curve.
A
%
.
A