Viessmann VITOTRONIC 300 GW2 Installation And Service Instructions Manual page 103

System components
Strap-on temperature sensor and immersion temperature sensor
17A or 17B
740
720
700
680
660
640
620
600
580
560
540
20 30 40
68 86 104
Return temperature in °C / °F
(continued)
17A or 17B
50 60 70 80 90
122 140 158 176 194 212
For measuring the return temperature.
Electrical connection
The sensor is inserted in socket
"17A" or "17B" on the control unit.
Check the sensor
1. Disconnect plug aJA or aJB in
2. Measure resistance of sensor at
3. Compare the value measured with
Technical data
Degree of protection: IP 32
Ambient temperature
during operation:
during storage and transport:
100
Additional information
the terminal compartment.
terminals "1" and "2" of the plug.
Return Resistance
in 
temperature
in °C / °F
30 / 86 569
40 / 104 592
60 / 140 643
the current temperature. If the
value differs significantly, check
installation and, if necessary,
replace sensor.
0 to + 100°C
32 to + 212°F
–20 to + 70°C
- 4 to + 158°F
103