Checking The Temperature Sensors - Viessmann Vitotronic SPS Service Instructions Manual

Checking the temperature sensors

All temperature sensors used are Pt1000 sensors.
The heat pump control unit reports a temperature sen-
sor fault if the measured temperature is not within the
possible range.
Example:
Outside temperature above 100 °C
Curve, Pt1000
1600
1500
1400
1300
1200
1100
1000
900
800
-50 0 50
Temperature in °C
Fig. 37
100 150
Fault messages also appear if there is a break in the
connecting lead or if the resistance has dropped due to
moisture or dirt on the connections.
Values that are too high suggest a poor connection.
Values that are too low suggest unwanted contact due
to moisture or dirt.
1. Disconnect at least one of the two connections
between the sensor and the heat pump control
unit.
2. Check the sensor resistance and compare it to the
curve.
3. In the case of severe deviation, check sensor
installation and replace the sensor if necessary.
Diagnosis
61