Temperature sensor diagnosis

Question

I wonder if somebody could help me identify where I am wrong:

I have an analogue temperature sensor in my hand and cannot find out what kind of sensor this is.

• It is a two wire crimped cylinder (diameter 6mm), used for domestic heating applications. It is equipped with a silicon cable.
• I first thought it would be a standard PT 1000 but a resistance measurement yielded a value of about 1.8KΩ when I warmed the sensor with my hand.
• The sensor has a positive resistance curve as the resistance was slowly rising when the sensor got warmer.
• The resistance was measured with ambient temperatures around 10°C.
• The sensor is an unused spare part, lying around for about 5 years and a visual inspection yields no abnormalities.

So that causes me doubts:

• I cannot find some standard, positive curved, temperature sensors with that values.
• I doubt that the heater manufacturer used some tailor-made temperature sensors when there are cheap, established sensors around (like a PT 1000)
• An measurement error seems unlikely as the difference to an established sensor type is way too much. Even an sub-par multimeter should not have that error-range.

Does somebody know a standard sensor with matching characteristics?

Answer 1

There are a plethora of crappy cheap base-metal RTDs used in comfort heating applications. Typically nickel or nickel-iron alloy.

There are a number of 'standards', including ~2K at about room temperature.