Which thermometer is correct?

[Boyd]

I have a Oneida Digital thermometer and a floating thermometer from the brew store. They both are accurate at freezing (32*F). However, when steeping grains, my digital is @ 152*F and my floating is @ 156*F. Which one should I trust?

 

[marubozo]

Try a test in boiling water and see if they differ in readings. That should narrow it down to which one is incorrect.

 

[RandomSF]

As you have found, one point calibration is inadequate. Calibrate them at freezing and boiling for a better indication of which is more accurate.

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A scientist with a thermometer knows the temperature of the object in question. A scientist with two thermometers is only confused.