PID Use and Tuning Questions

My first brew on an eBIAB with 5500w element and Auber PID went well enough, but had a few issues overshooting temps. I did auto-tune it, but I'm wondering how I can a) perhaps teak some of the constants and b) eliminate posisble user-caused issues.

Concerning b), I reset the PID several times in the brew-day in order to get the alarm to reset. I set the alarm at the protein rest temp then went to mill the grain. I wanted to reset the alarm once I was headed to sach rest temp, so I could time that rest, but the only way to do that seems to be a hard reset. Is there a way around this? Would this have messed up the PID?

Also, I cut power to the element a few times while leaving the PID on. I also removed the RTD probe when I did this (while mixing in grain, since the probe is in a floating lid right in the recirc port). I'm guessing both of these might have lead to problems since they would have messed up the PID's calculations.

I tricked the PID a bit by setting the Sach temp under by a few degrees until it got close. Once it settled in, it held temps excellently (149.9-150.1).

Thanks for any help!

"Removed the probe"

Where in the chain is the probe located? That has the potential to cause more of a problem than PID calibration.

Edit, floating in a lid.... See that now. If your element is on the bottom, that separation will keep your PID chasing temps. Lots of lag...

golfindia said:

"Removed the probe"

Where in the chain is the probe located? That has the potential to cause more of a problem than PID calibration.

Edit, floating in a lid.... See that now. If your element is on the bottom, that separation will keep your PID chasing temps. Lots of lag...

Click to expand...

But it is right in the stream of the recirc pump. The wort which comes from the bottom near the element is constantly flowing over it. Do you still think that's a big issue?

Thanks for the reply.

Is it a SYL-2352 PID ? Auber Instruments gave me these values P=350, I=40, d=2 and t=2 for beer brewing.

I found auto-tune useless, it jacked up my numbers 2 to 3 times higher.

I have gone one step further and set temperature display to celsius and offset my SV by 0.2C. You don't know the ferinheight, it could be almost one degree off.

1MadScientist said:

Is it a SYL-2352 PID ? Auber Instruments gave me these values P=350, I=40, d=2 and t=2 for beer brewing.

I found auto-tune useless, it jacked up my numbers 2 to 3 times higher.

I have gone one step further and set temperature display to celsius and offset my SV by 0.2C. You don't know the ferinheight, it could be almost one degree off.

Click to expand...

Those values are pretty useful. I'll have to dive in and check what they are after the auto-tune. Mine is the 2362, though. I assume the values would be universal, but I'm not sure.

I left the temp display on F and down to .1 degrees. Once I got ot my sach rest It stayed between 149.9 and 150.1.

Regarding alarm resets:
I think that PID has two alarms, and each alarm has a range that it triggers in. It doesn't have a way to beep once it gets to a temperature and then stop beeping. The workaround is to have a switch to "mute" the alarm.

Regarding the PID spooling up and how to reset things:
If the PID doesn't think that the heat it is putting out is working, it will try to apply more heat. This means that if you take the probe out of the mash then then PID will think "oh man, I'm at 10% and it's getting colder, I better go to 20%, then 30%, then 40%". The two fastest ways to get it to settle back down are to change the setpoint (way low) until it unwinds itself, or to reset the PID once you have the probe back in the mash. Of those two, resetting the PID is actually probably the best choice, and again, you can put a switch into your control box to reset the PID only.

The ideal situation would be to keep the wort flowing over the temperature probe the whole time. Just lift the lid less or tilt it and let the pump keep running while you stir. This way the PID always knows what's going on and doesn't freak out when the temperature randomly jumps.

BeardedBrews said:

Regarding alarm resets:
I think that PID has two alarms, and each alarm has a range that it triggers in. It doesn't have a way to beep once it gets to a temperature and then stop beeping. The workaround is to have a switch to "mute" the alarm.

Click to expand...

I've got the switch. I only wired one alarm. Even if I wired the second to the same alarm, the first alarm would still be making the alarm go off. The problem is that once you hit the temp, the alarm will sound continuously until the PID is shut off or muted by the switch, even after the alarm value has changed.

BeardedBrews said:

Regarding the PID spooling up and how to reset things:
If the PID doesn't think that the heat it is putting out is working, it will try to apply more heat. This means that if you take the probe out of the mash then then PID will think "oh man, I'm at 10% and it's getting colder, I better go to 20%, then 30%, then 40%". The two fastest ways to get it to settle back down are to change the setpoint (way low) until it unwinds itself, or to reset the PID once you have the probe back in the mash. Of those two, resetting the PID is actually probably the best choice, and again, you can put a switch into your control box to reset the PID only.

Click to expand...

I've reset by using the main power switch on the control panel. I also had some luck mitigating the overshoot by making my setpoint low until it got close (148 for sach rest) and then making it my actual desired value once I got close (150).

BeardedBrews said:

The ideal situation would be to keep the wort flowing over the temperature probe the whole time. Just lift the lid less or tilt it and let the pump keep running while you stir. This way the PID always knows what's going on and doesn't freak out when the temperature randomly jumps.

Click to expand...

I'll try to do it more this way. Thanks!

tennesseean_87 said:

But it is right in the stream of the recirc pump. The wort which comes from the bottom near the element is constantly flowing over it. Do you still think that's a big issue?

Thanks for the reply.

Click to expand...

But still a large column of mash between your probe and element. Just thinking it through it seems like it would be tough for the PID to level out a temp in that scenario. I have several 2352s and some cheap Inkbirds that I have used for sous vide, distilling, and RIMS brewing for quite a while. Can't remember the last time I've ran auto tune on any of them. Seems like just letting them go is enough to "teach" them.

golfindia said:

But still a large column of mash between your probe and element. Just thinking it through it seems like it would be tough for the PID to level out a temp in that scenario. I have several 2352s and some cheap Inkbirds that I have used for sous vide, distilling, and RIMS brewing for quite a while. Can't remember the last time I've ran auto tune on any of them. Seems like just letting them go is enough to "teach" them.

Click to expand...

I might try to restore default and see if that helps, or use the values posted above.

I'm open to thinking about my probe placement, but I'm not understanding your remark here. The way I'm looking at it is that the distance between the probe and element is shortened by the fact that liquid from the lower part of the mash (where the element is) is being pumped directly to the probe at the upper part of the mash. I thought a large part of recirculating was to evenly distribute the temperature of the mash, and I have assumed my set-up would do this. I have a 90* elbow through the lid pointing in such a manner as to whirlpool the mash, which I'm thinking will make it even more evenly distributed. I know a lot of people put the probe just past the output on the bottom of the kettle, and I figured a few feet of tubing insulated with foam pipe insulation wouldn't lose too much heat so as to give me a false reading or cause problems. If I'm missing something here, I definitely want to know so I can optimize my set-up.

tennesseean_87 said:

If I'm missing something here, I definitely want to know so I can optimize my set-up.

Click to expand...

You aren't missing anything except the test run. Use a thermometer to take a reading as deep in the grain bed as you can get, measure the temp coming out of the return, and then give the mash a really strong stir and measure everything again.

If all the readings are equal, you are a wizard... If they are all within a degree of each other, you are just fine.

If stirring it up causes the temperature to jump up or drop, you need better circulation. If you can't get better circulation then at least measure to find the hottest point, and use that to adjust what you set the pid to.

Keep in mind, if you stir it up and the temp changes dramatically, then your pid isn't actually sensing the mash temp well. You will never be able to get good control that way.