Question about auto-tuning on my system

[awarner322]

Hey guys.. So I have a 2 PID system. I measure the temperature of my mash using a probe right after my ball valve on the mash tun before it recirculates back through the coil in the HLT (the other is in the boil kettle).

My question is to relating to the auto tuning which I ran prior to the first batch. I used just water in the mash tun to recirculate thru the HLT coil when I auto tuned it. During my first batch I noticed that the PID is calling for output too frequently, and sometimes when the PV>SV even. It seems clear that the auto tune was not that successful. I started tweeking the P,I,D setting manually myself before writing them down...so I don't have those values anymore.

So my question is. Should I just repeat the auto-tune the same as before and expect a better result? Or is it possible that the addition of grain on a real brew day is causing me problems? Hopefully that makes sense.

Thanks guys!

 

[iijakii]

First off, what PIDs?

Also, you are using the MT sensor to drive your HLT/HERMS element? That's likely going to be a problem in regards to overshooting your temp.

 

[awarner322]

They are Auber Instruments. SYL-2352 is the one controlling the HLT via mash temps. What do you mean by MT sensor?

First off, what PIDs?

Also, you are using the MT sensor to drive your HLT/HERMS element? That's likely going to be a problem in regards to overshooting your temp.

 

[FuzzeWuzze]

They are Auber Instruments. SYL-2352 is the one controlling the HLT via mash temps. What do you mean by MT sensor?

I think hes stating that its recommended practice to hold your mash at a specific temp by controlling your HLT. Your mash sensor is nothing but a fancy temperature probe telling you what your mash is..you control it by increasing the temp of your HLT...for most of us thats by having the HLT 1-3 degree's above what you want your mash at due to losses in transferring the wort around through pumps and what not...depends on your system what that delta is.

 

[awarner322]

Hmm okay. It seemed like when I was researching how to set this up...the theory was to add the probe effete I did since that is what we are really concerned about...not what the hlt temp is. I assumed the system would be able to compensate for the way I did things with auto tuning. Am I off base here? Good news is it would be easy enough to punch a temp probe into the hlt I guess...

I think hes stating that its recommended practice to hold your mash at a specific temp by controlling your HLT. Your mash sensor is nothing but a fancy temperature probe telling you what your mash is..you control it by increasing the temp of your HLT...for most of us thats by having the HLT 1-3 degree's above what you want your mash at due to losses in transferring the wort around through pumps and what not...depends on your system what that delta is.

 

[FuzzeWuzze]

Hmm okay. It seemed like when I was researching how to set this up...the theory was to add the probe effete I did since that is what we are really concerned about...not what the hlt temp is. I assumed the system would be able to compensate for the way I did things with auto tuning. Am I off base here? Good news is it would be easy enough to punch a temp probe into the hlt I guess...

The HLT temperature is what matters. Whatever that is set to will dictate what your mash will get to eventually while pumping through your coil.

For example i have a 1.5F drop. So i set my HLT to 155.5 if i want my mash to hold at 154.

The problem with controlling via the mash is that your going to overshoot your temperatures a lot. If your at say 140 after doughing in and want to get to 155 for your mash on your current setup you'd set it and it would turn on your HLT to 100%. Seems good, until you realize that because your mash was controlling the HLT that by the time it got to 154F that your HLT is at 190F. This requires you to immediately turn off your pumps otherwise your wort will quickly keep rising past the 154 you wanted. Repeat this cycle turning on and off your pumps manually every 5 minutes to hold 154F because your HLT water is too hot.

On the other side, if you just set your HLT to 156 and pump continuously you know that your mash will get to 154-155 and never go any higher or lower as long as your HLT is held at 156. The PID auto tuning magic should be used on your HLT to have it hold a consistent temp.

 

[awarner322]

Ok...well that is an easy enough change to make. So I should just be able to switch that probe (outside of the kettle, after the ball valve) from the MT to the HLT, right?....assuming I recirculate the hlt the entire time with my second pump. Or would I be better off punching a hole in the kettle....or is that almost an indifference. I just want a consistent mash temp!

The HLT temperature is what matters. Whatever that is set to will dictate what your mash will get to eventually while pumping through your coil.

For example i have a 1.5F drop. So i set my HLT to 155.5 if i want my mash to hold at 154.

The problem with controlling via the mash is that your going to overshoot your temperatures a lot. If your at say 140 after doughing in and want to get to 155 for your mash on your current setup you'd set it and it would turn on your HLT to 100%. Seems good, until you realize that because your mash was controlling the HLT that by the time it got to 154F that your HLT is at 190F. This requires you to immediately turn off your pumps otherwise your wort will quickly keep rising past the 154 you wanted. Repeat this cycle turning on and off your pumps manually every 5 minutes to hold 154F because your HLT water is too hot.

On the other side, if you just set your HLT to 156 and pump continuously you know that your mash will get to 154-155 and never go any higher or lower as long as your HLT is held at 156. The PID auto tuning magic should be used on your HLT to have it hold a consistent temp.

 

[FuzzeWuzze]

Yes just measure the HLT water as its being pumped out and recirc'd back.