99
10
1
10 30 50 70 90 110
Temperature in °C
0.4
0.6
0.8
2
4
6
8
20
Resistance
in kΩ
Fig. 59
Sensor type: NTC 10 k
Ω
1.
■
Boiler water temperature sensor
Disconnect leads from boiler water temperature
sensor
A
and check resistance.
■
Cylinder temperature sensor
Disconnect plug
%
from the cable harness at the
control unit and check the resistance.
■
Flow temperature sensor
Disconnect plug "X3" at 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 on the heating water side
before replacing the sensor.
Checking the flue gas temperature sensor
The flue gas temperature sensor locks out the boiler if
the permissible flue gas temperature is exceeded.
After the flue system has cooled down, press reset
button
R
to cancel the lock.
Fig. 60
10
1
10 30 50 70 90 110
Temperature in °C
0.4
0.6
0.8
2
4
6
8
20
Resistance
in kΩ
Fig. 61
Sensor type: NTC 10 k
Ω
1.
Disconnect leads from flue gas temperature sensor
A
.
2.
Check sensor resistance and compare it to the
curve.
3.
In the event of severe deviation replace the sensor.
Troubleshooting
Maintenance
(cont.)
5778741
Diagnosis
