Checking The Temperature Sensors - Viessmann Vitovalor PT2 E11T Installation And Service Instructions Manual

Troubleshooting
Repairs
(cont.)

Checking the temperature sensors

Outside temperature sensor
Fig. 81
200
100
80
60
40
20
10
8
6
-20 -10 0 10 20
Temperature in °C
Fig. 82 Sensor type: NTC 10 k
1. Disconnect plug from the control unit.
!
2. Test the resistance of the outside temperature sen-
sor at the disconnected plug and compare it with
the curve.
3. In the event of severe deviation from the curve,
disconnect the wires at the sensor and repeat the
test on the sensor itself.
130
30
Ω
4. Depending on the test result, replace the lead or
the outside temperature sensor.
Temperature sensors inside Vitovalor PT2
For the electrical connection of the temperature sen-
sors, see connection and wiring diagrams from
page 193.
Danger
The temperature sensors are immersed in the
heating water (risk of scalding).
Drain the boiler before replacing the sensor. See
page 127.
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Fig. 83 Sensor type: NTC 10 k
1. Pull plug and measure the sensor resistance. See
connection and wiring diagrams from page 193.
2. Compare the sensor resistance with the curve.
3. In the event of severe deviation replace 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.
Unlock the appliance once the flue system has cooled
down (see operating instructions).
Ω