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I really don't trust my thermocouple that I have. Does anyone know an easy way to test the thermocouple to ensure it's completely accurate. I checked it in ice water for 0C, and it got pretty close, but when measuring something around 240C, I still don't trust it.

Are you comparing it against a thermocouple? If not, that's the FIRST step you need to take.

g.

The ice water was good to do. The next step is too bring water to a rolling boil and check with the thermocouple, it should read 100 degrees.
If it passes these two tests, I would assume the thermocouple is accurate. There will be small variations based on the fact that water boils
at slightly different temperatures based on elevation and impurities in the water. We are looking for close here not trying to calculate how to
land a module on Mars.

Thermocouples are inherently accurate (afaik). What he needs to do is compare the values from a THERMISTOR (in the hot end) to the value reported by a thermocouple.

The boiling water/ice water trick is useless when you've already installed the thermistor in the hot end and you don't want to screw it up by removing it, performing a pointless test and then reinstall it.

BUY. A. THERMOCOUPLE.

g.

geneb wrote:Thermocouples are inherently accurate (afaik). What he needs to do is compare the values from a THERMISTOR (in the hot end) to the value reported by a thermocouple.

The boiling water/ice water trick is useless when you've already installed the thermistor in the hot end and you don't want to screw it up by removing it, performing a pointless test and then reinstall it.

BUY. A. THERMOCOUPLE.

g.

Gene, he has a thermocouple. He is just trying to determine the accuracy of it. He is not talking about testing the thermistor. Either I or you misread the question.

I agree with eaglezsoar. I tested my thermocouple meter against 100c boiling water and my temps were not that far off, maybe a degree or two. I never even bothered to do 0c test.

my thermocouple meter manual only suggest to calibrate against 100c boiling water.

My apologies. I keep seeing people doing stupid things with thermistors and it's become my default reaction.

g.

geneb wrote:My apologies. I keep seeing people doing stupid things with thermistors and it's become my default reaction.

g.

Perhaps we need a "Stupid Thermistor Tricks" sticky?