I've got a BrewZilla Gen4 and have been brewing with it the last several batches. Really digging it. I do a lot of step mashes, so was instantly thrilled that when setting up a mash profile I could either set it up to just step to a temperature over a fixed amount of time (typical) or start the step timer when I hit the target temperature. I instantly gravitated to "when I hit the target temperature".
However, the drawback I've seen is it literally means "when I hit the target temperature". And with the PID controller base gains, it pretty much never overshoots. Looks beautiful from a control perspective to come up like a square wave, but when the temperature never crosses that line, I get several extra minutes at the mash steps, which leads to an overall longer mash. Maybe in the future, the RAPT programming will have the ability to set a "target +/- 1 degree" or something to start the timer. In the meantime, I figure I need to play with the P, I, D gains to get a bit of overshoot when coming up to that first step.
Have others run into this? Figured out a suggested process or crude adjustment that gets them the overshoot on the first rise to temperature, but doesn't make an oscillating trainwreck after arriving there?
Base PID Gains:
First iteration of tweaked PID gains (tweaked P and I up by 10% each):
I'm thinking back to my college Controls classes, and I'm thinking I want to go back to base, but tweak up the I term more like 20% instead of 10%. Build up a bunch of controller gain while it's sitting a long way away from the target, that it ends up overshooting before being able to correct itself. But trying to tinker with as few batches as possible to hone it in. I guess I could aslo get there by turning off PID, since it would just heat until it hit the target.
However, the drawback I've seen is it literally means "when I hit the target temperature". And with the PID controller base gains, it pretty much never overshoots. Looks beautiful from a control perspective to come up like a square wave, but when the temperature never crosses that line, I get several extra minutes at the mash steps, which leads to an overall longer mash. Maybe in the future, the RAPT programming will have the ability to set a "target +/- 1 degree" or something to start the timer. In the meantime, I figure I need to play with the P, I, D gains to get a bit of overshoot when coming up to that first step.
Have others run into this? Figured out a suggested process or crude adjustment that gets them the overshoot on the first rise to temperature, but doesn't make an oscillating trainwreck after arriving there?
Base PID Gains:
First iteration of tweaked PID gains (tweaked P and I up by 10% each):
I'm thinking back to my college Controls classes, and I'm thinking I want to go back to base, but tweak up the I term more like 20% instead of 10%. Build up a bunch of controller gain while it's sitting a long way away from the target, that it ends up overshooting before being able to correct itself. But trying to tinker with as few batches as possible to hone it in. I guess I could aslo get there by turning off PID, since it would just heat until it hit the target.