Spheros Thermo S 160, Workshop Manual

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Thermo S 160/230/300/350/400 5 Troubleshooting and error correction
511
5.5.4 Resistance check of the temperature sensor
with integrated overheating protection
Prior to removing the temperature sensor, the
overpressure in the cooling system must be released by
opening the cooling lid. Observe the risk of injuries due to
increased coolant temperature. Possibly let heater
additionally cool down and have collecting container
ready for discharged coolant.
Inspection
t Inspect temperature sensor, plug and cable
for damage and proper fit.
t Remove temperature sensor (see 8.3).
t Perform the electrical test using a measuring device
suitable for resistance measurements.
The water temperature sensor and the overheating
protection should indicate values according to the
charts.
Preferably the resistance should be measured at an
approx. consistent temp erature of 20° C and
approx. 100° C (immerse sensor up to the copper
gasket ring into boiling water).
Prior to reading the value, the sensor should be
exposed to the temperature for approx. 20 seconds.
t Install temperature sensor (see 8.3).
Resistance vs. temperature chart
Fig. 503
Fig. 504
Fig. 505
Pin 3 & 4
Pin 1 & 2
Overheating protection
Water
temperature sensor
100
110
120
130
140
150
0 20 40 60 80 100 120 140
1000
1100
1200
1300
1400
1500
20°C: 1070 …1086?
20°C: 107…109 Ohm
100°C: 137…140 Ohm
100°C: 1377…1393?
Overheating protection (pin 1 & pin 2)
Temperature [°C]
Water tem
p
erature sensor
[Ohm
]
Overheating protection [Ohm]
Water temperature sensor (pin 3 & pin 4)
WARNING