Hi guys! I just recently upgraded to Rancilio Silvia from a Gaggia Classic and to make things even better installed a PID on the Miss. The PID is the Sestos DS1 which is pretty much an Auberins knock-off. I'm using a K-type thermocouple attached to one of the bolts of the thermostats on top of the boiler. Everything works perfectly except that I get an overshoot of 2-3*C after a shot. I know that it's not much and I usually don't care about it but when I have friends over it makes making multiple drinks problematic. The settings for P, I, and D derived from the auto-tune function are: 660/9999, 214/9999 and 117/9999. I've read quite a lot of threads but most PID controllers have quite narrower ranges for the three variables. I increased the D term to around 300 which kind of solved the problem but overshoot is still present. What really bugs me is that very often the temperature reaches the setpoint of 95*C and settles there but the PID again turns on the SSR and it overshoots to 96-97*C. Also I don't think the Sestos has a function similar to the damp constant of the Auberins or the Anti-reset windup of the REX C100. Any suggestions? Thanks!
Conceptually, you have a steady state condition, then you have cool water coming in, then the cool water suddenly stops. You can't avoid all under/overshoot in such a case with even the best controller. A smarter controller that understands the two states and knows when water flow is starting and stopping would help. I use a micro-controller to do this.
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