Something went to hell here…  This is the first time I have encountered this.  Weird that everything seemed OK at the beginning and end of the roast.  While roasting I thought that this might be the result of the inlet temperature banging against the 700F limit I set but clearly there is an instability here.  Normally roast should stay below the 700F inlet limit so that end of the control algorithm is not in play.

Coffee turned out OK.  Still not liking this Guatemala all that much but I don’t have all that much more to go through.

2 thoughts on “Jeepers!”

  1. How are you able to get an even roast with 260g of coffee? I roast about 225g, and I’m thinking of dropping lower to achieve a more even roast.

    1. I don’t seem to have much issue with roast evenness but with this large of a charge, the airflow is too restricted and I bump up against the temperature limit I have imposed on inlet temp. When this happens, the control loop switches to using the inlet temp instead of the outlet temp. Throws off the PID control stability. I pretty typically stick to 250g and don’t see much issue with that level of charge.

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