Different temp readouts with different fan speeds

Hello everyone,

I’m using same bean, same preheat and same 333gr batch size, same drum speed at 9, but different power and fan setting in comparing roasts.
With lower power around 6 and lower fan settings at 3 I have lower temp readouts all the way, but primarily noticing FC temp at ~195 ibts, ~166 bt
With higher power at around 7 and higher fan setting at 6 I have higher FC temp at ~204 ibts, ~177 bt.

Is this a normal behavior?
I would expect same bean to have FC at the same temp or at least at the less different.

Happy to hear some thoughts.

Lower/slower with the roaster means the bean is more evenly heated through, which equates to a more accurate and lower FC temp.

Faster/hotter means the outside of the bean is hotter than the inside, and you’ll see higher FC temps.

FC is governed by internal bean temperature.

ETA - And both Bullet temperature sensors read external bean temperature.

So in conclusion, what I’m saying is that internal and external bean temperature aren’t always the same (actually, almost never), so we are inferring internal bean temperature based on external bean temperature. Higher ROR yields a less accurate inference of internal bean temperature.

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