Checking The Temperature Limiter - Viessmann VITODENS 111-W Installation And Service Instructions Manual

Repairs
(cont.)
20
10
8
6
4
2
1
0.8
0.6
0.4
10 30 50 70 90 110
Temperature in °C
Fig. 41 Sensor type: NTC 10 k

Checking the temperature limiter

If the burner control unit cannot be reset after a fault
shutdown although the boiler water temperature is
below approx. 95 °C, check the temperature limiter.
Fig. 42
Ω
A
1. Disconnect leads from outlet temperature sensor
A .
2. Check sensor resistance and compare it to the
curve.
3. In the event of severe deviation replace the sensor.
Danger
The outlet temperature sensor is directly
immersed in the DHW (risk of scalding).
Drain the boiler on the DHW side before
replacing the sensor.
1. Disconnect the leads from temperature limiter
2. Check the continuity of the temperature limiter with
a multimeter.
3. Remove faulty temperature limiter.
4. Install a new temperature limiter.
5. Reset by pressing "Reset" on the control unit (see
page 42).
Troubleshooting
A .
47