Hi - I have a BrewPi legacy system tuning a fermentation chamber and am overall very pleased with the performance. I have noticed after a few days of changing the temperature set point, the errors increase. It will still control within 0.5 degF, but as you can see from the charts below, the error starts small and builds. Please ignore the large spike as that is when I took the thermometer out of the thermowell temporarily.
I am sure that this needs a small tweak to the PID constants, but I don’t want to change these without a full understanding of what I’m doing and value the opinion of the PID experts on this board.