BIAB Issues Holding Temp

[GregKelley]

I have a 10 gallon pot with a 5500W element. Controlled by the SYL-2352 PID. I went through the auto tune and had some issues so I contacted Auberins. They gave me the settings for I P D and T but said that the default will work fine.

My temp sensor (RTD) is on the spigot coming out of the pot. I recirculate the liquor during the mash with my pump.

My issue is that my PID keeps shooting my temp a degree or two past the set value. For instance, when I set my strike temp to be 157, it hit 159. My mash temp was then set to 152. I watched the PID fire the element when it needed to heat things and it jumped it to 154. Note that these are all temps observed on the PID.

I also see my flow rate coming out of the pump affect the temp. Has anyone notice that? It appears to jump up when I increase the flow. I have it turned down pretty slow so that my return hose doesn't jump out of the pot.

Any thoughts or comments are appreciated.

 

[pricelessbrewing]

Just set it to two degrees less than you want...

 

[GregKelley]

Just set it to two degrees less than you want...

That doesn't work because for a period of time my temp would be 2 degrees less. My point is that the temp bounces.

 

[cooper]

Is there a way you can dial back the power going to the element when the temp gets close to your set point? That might help keep it from bouncing around so much.

 

[GregKelley]

Is there a way you can dial back the power going to the element when the temp gets close to your set point? That might help keep it from bouncing around so much.

That is what the PID does. It is configured to adjust things accordingly so as not to blow through the set point.

In talking with some others, I think my issue is that I'm throttling the flow of the liquor. If I open that up completely, I would get more uniform heat distribution and so a better read on the temp and better control.

 

[jonnyhammastix]

I recently purchased an E-BIAB system and had the same problem. By any chance, when you autotune are you using the appropriate quantity of water that you would mash at? Also, do you have one or two elements?

 

[joshindc]

Did you ever figure out how to auto-tune the controller? If so, did you auto-tune it with grain in the pot and at the flow rate you use?

If not, you can tune it manually using the techniques in the PID wikipedia article:
http://en.wikipedia.org/wiki/PID_controller

You may have issues getting a temperature plot out of your PID though. Reading that article may help you understand how to adjust the various gains too.

Alternatively, I find that throwing a couple towels/a blanket over my pot pretty much solves this problem for me. It cuts way back on the cycling of the element.

 

[1MadScientist]

Try setting the Hy (Hysteresis Band) to 0.1 and then auto-tune.

MS

 

[GregKelley]

I recently purchased an E-BIAB system and had the same problem. By any chance, when you autotune are you using the appropriate quantity of water that you would mash at? Also, do you have one or two elements?

Yes, I used the same amount of water that I have now. I use one element.

 

[GregKelley]

Thanks all. In speaking with Auberins (who supplied the PID), it appears that my mistake was constricting the flow through the pump. I need to have it pumping at full throttle in order to keep from having heat pockets build up in the kettle. I'll give that a try on my next brew day.

 

[TexasWine]

Thanks all. In speaking with Auberins (who supplied the PID), it appears that my mistake was constricting the flow through the pump. I need to have it pumping at full throttle in order to keep from having heat pockets build up in the kettle. I'll give that a try on my next brew day.

Be careful with a full throttle pump. I took my brand new ebiab rig out for its inaugural brew this past weekend. When I turned the pump on after doughing in I had a fully open suction valve. That full throttle flow rate on the pump caused the grain bed to compact and I ended up pumping most of the wort from under the bag to the top side of the grain bed, and I over flowed the kettle!

Took me a while to figure out what was going on. After I realized it I stirred up the grain bed with a big spoon, and then I gradually opened the valve and never got to full throttle again.

 

[coldbrewnoob]

Sorry, but its not going to make one crap of difference. 2degrees is a joke, right?

 

[1MadScientist]

Other methods are, after the mash temp. is stabilized, is to turn off the pump recirc and (cover and wrap) or set to manual mode to 5% power and come along every 20 minutes to stir. Both have been recommended to me.

I have a controller with that Auber PID, but haven't had the time to brew with it yet.

I don't have a pump as of yet

MS

 

[GregKelley]

Sorry, but its not going to make one crap of difference. 2degrees is a joke, right?

That's not what I've heard. A couple of degrees can make a difference with the fermentability of the wort.

 

[JPicasso]

Sorry, but its not going to make one crap of difference. 2degrees is a joke, right?

I think this is a good question. Especially with BIAB, I think the general procedure is to try and hit mash temp, or a degree or two above, then "let it ride". With a blanket, it will lose a few degrees and whatever, everything evens out in the end. This appears especially true since there are threads with some experimental evidence that 30 minutes or even less, is all that is required for all or the majority of the mash to finish. So even if you start at say, 152 and at the end of an hour you're at 148, you probably did most of your mashing at the temperature you wanted.

That said, if I spent money on a PID controller and pump, +-2° would not be acceptable. +- 1 might be, but even better if we could keep the cycle within two readings on the thermometer.

As for the original problem, good flow and more frequent stirring sounds like a good plan! Otherwise, you have a slug of hot water slowly making it's way down the grain bed, and when it finally evens out, you've been heating too long.

 

[cooper]

Be careful with a full throttle pump. I took my brand new ebiab rig out for its inaugural brew this past weekend. When I turned the pump on after doughing in I had a fully open suction valve. That full throttle flow rate on the pump caused the grain bed to compact and I ended up pumping most of the wort from under the bag to the top side of the grain bed, and I over flowed the kettle!

Took me a while to figure out what was going on. After I realized it I stirred up the grain bed with a big spoon, and then I gradually opened the valve and never got to full throttle again.

Would it make sense to put a valve on the outlet side of the pump to control the flow out so you don't end up with too much wort on top of the grain bed. I can understand not constricting the flow into the pump but a lot of folks will restrict it on the outside.

 

[GregKelley]

Would it make sense to put a valve on the outlet side of the pump to control the flow out so you don't end up with too much wort on top of the grain bed. I can understand not constricting the flow into the pump but a lot of folks will restrict it on the outside.

That's exactly what I have. I have a valve on the spigot and on the outlet side of the pump. I was restricting on the outside of the pump and was recently told not to in order to maximize the flow.

 

[doug293cz]

That's exactly what I have. I have a valve on the spigot and on the outlet side of the pump. I was restricting on the outside of the pump and was recently told not to in order to maximize the flow.

If you are going to throttle the pump flow, then it needs to be on the outlet side of the pump. Throttling using a kettle valve can cause pump cavitation and damage.

You do want to run at the maximum recirculation allowed by the flow out of the bottom of the pot. You might have to throttle the flow to keep the grain bed from compacting and slowing or even stopping kettle drainage.

Brew on

 

[GregKelley]

If you are going to throttle the pump flow, then it needs to be on the outlet side of the pump. Throttling using a kettle valve can cause pump cavitation and damage.

You do want to run at the maximum recirculation allowed by the flow out of the bottom of the pot. You might have to throttle the flow to keep the grain bed from compacting and slowing or even stopping kettle drainage.

Brew on

I don't throttle coming out of the pot when I'm using the pump

 

[jonnyhammastix]

Be careful with a full throttle pump. I took my brand new ebiab rig out for its inaugural brew this past weekend. When I turned the pump on after doughing in I had a fully open suction valve. That full throttle flow rate on the pump caused the grain bed to compact and I ended up pumping most of the wort from under the bag to the top side of the grain bed, and I over flowed the kettle!

Took me a while to figure out what was going on. After I realized it I stirred up the grain bed with a big spoon, and then I gradually opened the valve and never got to full throttle again.

I had the same thing happen to me my first brew day with the new E-RIMS BIAB, however i lucked out and killed the pump before i had the spill. Best thing to do is just open it slowly, same way you would vorlauf with a three vessel all grain system. The suction created from your pump will pull the grains down and compact making the flow out of the valve faster than the wort can settle back down and circulate.

Also, i do not agree with the two degrees being a joke. Brewing is an art and if you want to color outside the lines that's fine, however i take pride in hitting the numbers that i spend the time working on while i create my recipes. That's just one mans opinion though, not being a hater.

 

[watermelon83]

Be careful with a full throttle pump. I took my brand new ebiab rig out for its inaugural brew this past weekend. When I turned the pump on after doughing in I had a fully open suction valve. That full throttle flow rate on the pump caused the grain bed to compact and I ended up pumping most of the wort from under the bag to the top side of the grain bed, and I over flowed the kettle!

Took me a while to figure out what was going on. After I realized it I stirred up the grain bed with a big spoon, and then I gradually opened the valve and never got to full throttle again.

Don't throttle the pump input, throttle the output.

 

[TexasWine]

Don't throttle the pump input, throttle the output.

Therein lies the problem. I'd prefer to throttle the out, but I only have a valve on the suction. Every engineering bone in my body hates throttling the suction, but that's my set up for now. I'm sure I'll change it up soon