Auber PT100 jumping around by 4 degrees

It's the one on the outlet of my HLT, screwed into the tee in a Kal-style build. It jumps around by 3 or 4 degrees all the time now, going from say 149 to 152 to 150 to 153 to 151 to 149 etc. It's not the cable or the PID because plugging a different PT100 (like the one in my BK) into the same cable does not jump around.

What can go wrong with the RTD itself that might cause this, and do I need to get a new one? It's only about 3 months old. Thanks!

Did you try autotuning? Mine was doing the same thing but it was when I switched to a smaller probe. After I autotuned it was spot on again

Could there be a wet connection somewhere? That has caused me issues in the past.

stlbeer said:

Could there be a wet connection somewhere? That has caused me issues in the past.

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Don't think so, it happens even a day or two after brewing, and when the system is dry. I'll try an autotune though.

must be the probe. I swapped it out for a different one (still auber pt100 but smaller threads plus a bushing) and this one doesn't jump around. I'll probably send it back to auber and see what the say.

Erratic readings means the electronics is sensing varying resistance. When that happens in my brewery the answer is always dirty/oxidized/wet/wort stained contacts in the plugs that connect the RTD's to the controllers. No guarantee that this is what is plaguing you but check/clean all connections/connectors.

The auto parts store will have "electrical contact cleaner" which you could spray on the RTD and the cable to eliminate a connection problem.