Using a PID to control a pump in a HERMS setup? A no-no?

[Bobby_M]

Yeah, I know direct-fire is different. I was just wondering, for sake of discussion, if we had any hard numbers by the brutus guys who use similar electronic control logic to ensure the wort doesn't exceed the target temp.

Bobby, how did you come up with the 1 gpm maximum on recirculation?

I pulled that out of my ass like all the other figures in the thread

I have to run the March output valve at less than half open and I still have to re-stir the mash about every 20 minutes or the siphon tube starts sucking air.

 

[The Pol]

I pulled that out of my ass like all the other figures in the thread

I have to run the March output valve at less than half open and I still have to re-stir the mash about every 20 minutes or the siphon tube starts sucking air.

What is YOUR crusher gap Bobby??

 

[Bobby_M]

I haven't checked it in a while because I lost my feeler gauge set.

 

[np0x]

Good stuff...so i have a herms, and i have done steps in it, although I choose to call them ramps for all the reasons listed above. All i can offer right now is the ability to offer some data at a later point.

I use a convolutus cfc for a heat exchanger and a very small volume of water in my 3000 watt heat tank. I recently got an insulated keggle(1/2 inch of rubber) and I am looking forward to doing a step mash or two to see what kind of temperature rise i can get. I have instrumentation on my input as well as my output side of my HEX, so I can give a graphical response to it all once completed.

Not delving into the physics of it too much of it, just doing it by mass, if i have a 20lb grain bill, that will contain an immovable mass of the 20lbs + 2.5 gallons of water(absorbed into the grain) getting me to about 32lbs of mass not moving through the HEX, Leaving the work to the remaining 7.5ish gallons of water(62.5)....I will do a step mash on my next brew and post the graph... assuming temp entering the HEX compared to exiting will offer any resolution to this conversation. Asymptotic approaches to temperatures be damned. All of which is to say we need to brew...weather is breaking on the northern virginia finally...

 

[Lil' Sparky]

I pulled that out of my ass like all the other figures in the thread

I have to run the March output valve at less than half open and I still have to re-stir the mash about every 20 minutes or the siphon tube starts sucking air.

I wasn't trying to be a smartass. I just wondered how you came up with that #. I don't recirculate continuously, so I've been able to run mine full-flow during the time I recirculate without any problems. That's with most grain bills - wheats seem to be a little more sticky. I've also kept my barley crusher at the factory setting, so that may play a role, too.

 

[Bobby_M]

No, the question was fair and I'm admitting that it's a rough estimate. I was really disappointed to find that I couldn't continuously recirculate more than a trickle without babysitting it. One batch got pretty badly scortched when I compacted. I didn't catch it for like 4 minutes. I'm sure a lot of this has to do with my burners and their inability to run at a "simmer" type flame. If they were more adjustable, I'd be able to run the pump nice a slow without worrying about spot overheating.

 

[np0x]

I was really disappointed to find that I couldn't continuously recirculate more than a trickle without babysitting it.

I don't know what your details are, but I was having some issues as well, but I made an effort on the last two brews to really start slow and get the grain bed floating before I started an aggressive circulation. I have a perforated false bottom(stainless steel with the little 3/16th" holes) and march pumps running through 1/2 inch tubing. I found that if I started really slow the grain would stay up top and as it settled (upwards if that's possible) i was able to start flowing faster and faster as it got all locked together. I also was having stuck mashes and stuff, so i feel your pain, start at a trickle and slowly work up...of course I probably will have a stuck mash next time because I post all this, but heh, take one for the team and all that. (I am doing 10 gallon batches in keggles).

 

[Bobby_M]

I'll try that next time I brew. I also plan to use 5% rice hulls from now on also.

 

[conpewter]

I'd still like to get the thoughts on why it is such a bad idea to heat the circulating wort to above your target temp to heat the rest of the wort/grain faster.
https://www.homebrewtalk.com/f11/us...rms-setup-no-no-95372/index2.html#post1263612

 

[Lil' Sparky]

I don't think it's such a bad thing, as long as the wort out of the HEX isn't WAY above (not sure how to quantify that) the target. The wort will only be higher than your target for a short time. This is expecially true when you begin the step. If your mash is at 122º and your wort out of the HEX is 160º, it'll be back down below 150 almost as soon as it's added back on top of the mash. I'm not a chemist, but it doesn't sound like you would severely denature the alpha/beta enzymes doing this.

Also, I don't think you'd want to continue doing this as your mash gets close to your target because you can overshoot it.

 

[np0x]

I'd still like to get the thoughts on why it is such a bad idea to heat the circulating wort to above your target temp to heat the rest of the wort/grain faster.

It's "bad" because the enzymes are in solution, you are denaturing(unintentionally) if you have a high return temp, in an extreme case you would be denaturing a lot of them. The number and impact of the denaturing would be something I cannot characterize and would impact different recipes differently depending on adjuncts and qty of excess enzymes. All mash temps are denaturing some enzymes, higher temps denature faster.

 

[Bobby_M]

I guess it really depends how much hotter. I don't have concrete resources handy, but the optimum temp range for each enzyme might be 10F wide or so, but it falls off sharply on both ends. Obviously the higher the temp is, the faster the denaturing process. If you're shooting for a 148F beta rest, I wouldn't want the wort hitting 175F. Now, I understand we're talking about short bursts of maybe 10 seconds so maybe you're onto something.

I keep reading that b-amylase denatures at 70c/158f. How much in how long though? I'd have to think even running the same bulk of it up to 170F even for two or three 10 second bursts would be bad.


Edit.. more data:
http://www.byo.com/stories/techniqu...ps/632-fermentability-a-mashing-out-mr-wizard

" If malt and water are mixed together at 158 ºF (70 ºC) several things begin to happen. Starch begins to gelatinize, beta amylase begins to denature and alpha amylase begins to cleave amylose and amylopectin in smaller molecules. This temperature is well above the optimum temperature for beta amylase, but that fact does not stop beta amylase activity and maltose production is seen. Over time, the population of beta amylase enzymes denatures and those molecules that are active keep working until they denature. The time period depends on environmental conditions and enzyme concentration.

The same thing happens with alpha-amylase during mash-off. The temperature increases, the last bits of ungelatinized starch gelatinize and alpha-amylase activity continues until the population of alpha amylase enzymes has been completely denatured. Everything has a time component and these reactions are not able to occur instantaneously.

So it is logical to conclude from such laboratory experiments (and the data is out there demonstrating these phenomena) that mashing at temperatures above the denaturation point of a particular enzyme does not instantly stop enzymatic activity."

More from homedistiller:

The more interesting factor is the denaturing of enzymes. When enzymes break their internal weak fold to fold bonds they lose their shape and so their effectiveness. In a few cases this denaturing is reversible - but this is rare. The major cause of denaturing in the mash is temperature. If enzymes are involved in collisions (or vibrations) too energetic then their internal structures change. They are still proteins, but they are no longer enzymes. Under a fixed set of conditions, the rate at which enzyme denature due to temperature is akin to the way radioactive material decays, or the charge on a capacitor bleeds off. It makes sense to describe it in terms of a half-life. A 1.25qt/lb 65C mash (and other conditions of pH etc), the half-life of beta-amylase was about 16 minutes. This means that the first 16 minute mash interval will have twice the activity of the second interval and four times the activity of the 3rd interval, and so on, assuming other conditions are constant (which they are usually not). The enzyme decay rate with increasing temperature is also exponential in nature, but is much greater than the activity increase and usually in the range of 6X to 36X per 10C increase !! This means the half-life time decreases markedly with temperature increase.

Another angle on this is to consider the time it takes to fully stir a hot step infusion or decoction infusion. If you're adding 210F water, there's a brief time where a portion of the mash is exposed to denaturing temps. By brief I mean, less than a minute while you're stirring and temps are equalizing. It's probably about the same as heating to 170F in short bursts.

 

[kladue]

FWIW the 1 gpm flow through the mash has been the upper practical limit with a 15.5" Dia. screen wire false bottom. Having a flowmeter in the wort circulating circuit enabled testing of higher and lower flows with various grain bills, crushes, and water ratios. From about 5 years of flow testing it appears you could circulate above 1 gpm for a short period of time but the grain bed compacted and flow rates fell well below .25 gpm until the pump was stopped and mash bed was stirred to loosen compaction. Would really like to see the system with 2.5 gpm recirculation rate and the method used to measure flow in operation while mashing.

 

[Lil' Sparky]

Slightly off topic from the original posts/questions, but it's relevant to the last page or two...

As I've said before, I've got a direct-fired MLT, but I've never really tried to monitor things very closely, so I had no idea how fast I could do steps, or how high the wort at the bottom of the MLT was really getting.

I brewed this weekend and thought I'd post some notes for comparison. I recently installed a temp probe at the pump so I can measure temps out of the MLT to ensure I'm not overheating the mash. I took some pics and video, but I haven't had a chance to load them up on my website yet.

We did two 10 gal wheat beers. I had forgotten to order rice hulls so we did a beta-glucan rest at 110º to break up the gums in the wheat to help avoid a stuck mash (worked very well, BTW). After that I wanted to step through the typical protein rest range (122-135) quickly to save some of the head producing proteins.

During the step, I kept the valve on the pump open about 1/2. Initially I was able to turn the burner up fairly high and got a temp differential of ~ 25º between the probe in the mash and the probe at the pump. Within just a few minutes the output at the pump was at my step target (153º), so I was able to adjust the burner down, and I ensured the output from the MLT stayed below 160º. The total +43º step took < 20 mins, but most of that time was spent going from the 140s to my target.

Once at my sacc rest temps, I continued to recirculate the mash and monitor the temps. I had to fire the burner briefly for the first mash after it had lost 1º, and the 2nd one never moved (but at that point I was boiling beer #1 right next to it, so it was probably getting a little heat from that burner).

Is it a set-it-and-forget it system? No, but it did make me question if automating the mash temps with a HERMS/RIMS is worth the trouble for me.

 

[kladue]

An approach to the herms setup would be to move the exchanger out of the HLT and use a CFC type exchanger with a pump and control valve in the water side. You should be able to match a voltage output PID to a low voltage HVAC zone valve with a voltage control input for automatic control of wort temps leaving exchanger. The main question would be is it worth the investment in what would be a simple monitor and adjust manual operation for step mashing with a CFC, pump, and ball valve.

 

[np0x]

So i did a somewhat chaotic brew day this sunday, but I still was able to gather some information in regards to HERMS and step mashes. All along the words asymptotic kept coming to mind, and I had had this thought before, but never captured the data...but we will get to that. Initially i got my strike water up to temp using my HEX only, this is a pair of 1500 watt elements, that got me a 50F rise in temp in about 20 minutes(reading the lighter of the two lines in the graph(the herms sending side)) about 2.5 F a minute.

This is what is to be expected, nice clean flow, no pesky grain, everything is circulating. I got up to a low temp of about 122 for a nice step mash experiment, for this board specifically, so appreciate this already, cause the day gets ugly...

Anyway, I dough in and then get weird flow issues, so bad in fact that end up taking all 20lbs of grain and 5 gallons of water OUT Of the mash tun trying to figure out why the whole thing is stuck. About the time my wife joins me for a cup of coffee and i sit down looking at the mess i have on my hands(and arms) i notice that the inlet to the pump has about 3 inches of grain in the hose, ok back on track everyone back into the pull back to the original experiment, what's an hour or two extra in the mash time(it's a saison, I expect some killer attenuation)...that's basically all the data points from 1500-900, now the part we were talking about...

It's all going swimmingly UNTIL we get close to our mash temp, the differential on the return temp(the same as my target 152) and the mash temp decreases until it gets to a point that it will take an infinite amount of time before I ever actually get to mash temp. Since the returning liquid is the same as my target it can't actually raise the temp significantly as it gets close. I feel the graph shows this rather well. Also running cool mashes with the herms might be dodgy, what with stuck mashes and all that, although i don't know if what I had would really count, it was really a clogged pump. What fun! Up to my elbows in starchy mash...i guess I should be thankful it was only about 115F, it was like a nice hot tub, instead of a scalding kitchen accident.

For those interested, the square graph at the bottom of the graph is the HEX cycling on/off...The highest line(if it wasn't already obvious) is the return from the HEX, and the slightly lower line is the exit from the mash tun going into the HEX.

Cheers.

(and I can't tell you how close I came to just saying hell with it and doing a decoction.)

 

[Lil' Sparky]

I'd like to see that graph on a "good" brew day when you don't have a stuck mash. I take it that's what all the erratic behavior between ~ 1300-900 was all about??

It looks like you can get a +30 deg differential with your HERMS, too. That seems like some pretty good heat transfer taking place in your HEX, and your elements seem to do the job.

BTW - What's the x axis scale? It looks like you ramp from 113 to 145 pretty fast (between 800-700). How much time does that represent?

 

[np0x]

My HEX is my convoluted wort chiller(and heater)...it puts some heat across, the x-axis is somewhat difficult to read in this context, each block is 200 seconds(20 10 second samples). The 1300-900 was when i had ALL the mash in buckets OUT OF THE BREWERY...so the temperature probes were reading ambient air or hot water from the hex-all of it meaningless, ignore that part, left in purely for your visual enjoyment...fun!

 

[The Pol]

I'd like to see that graph on a "good" brew day when you don't have a stuck mash. I take it that's what all the erratic behavior between ~ 1300-900 was all about??

It looks like you can get a +30 deg differential with your HERMS, too. That seems like some pretty good heat transfer taking place in your HEX, and your elements seem to do the job.

BTW - What's the x axis scale? It looks like you ramp from 113 to 145 pretty fast (between 800-700). How much time does that represent?

I think that he said each block is 200 seconds, so that would be 800 seconds, or about 13-14 minutes.

Is it showing that your mash never really reached 150F??? Was this due to the slowing of the MLT heating since you werent OVERSHOOTING the return wort temp??

My concern with overshooting the return wort temp. is this... stratification in the MLT. If you heat the wort to 160F in the HEX and return it to the MLT. The top of the mash will be nearing 160F when the bottom is much cooler. To me, this makes having a HERMS a moot point, because you have effectively lost temp. control and your mash is a hodgepodge of temperatures.

EDIT: It looks like you had 6 samples from the time that the HLT output started heating, til your mash reached its max. (nearly 900-600) That is 1200 seconds, 20 minutes... I am just personally not comfortalbe doing a 20 minute step, if I am reading it right.

 

[Lil' Sparky]

I still don't quite understand the x axis. I know you said 200 secs/block, but 5 blocks = 200 samples, which makes me think there are 40 samples/block, not 20.

Anyway, it looks like the HEX input climbs from 113-145º in 3 blocks (10 mins?), and is only in the 120-138º range for a block and a half (5 mins). That's about what I saw with my direct-fired system Sat and seems acceptable to me. The difference I had was I was able to reach my target temp faster from the 145º range because I DID overshoot my target, but never more than a few degrees.

POL - I get your issue w/ stratification during a rest, but I don't quite understand the problem w/ stratification during a step. In fact, I'd say in a way it's a good thing, because you're already eliminating some of the effect of the enzymes in the range between your rests from the very beginning because the higher temp at the top of your mash is denaturing those enzymes.

I think the bottom line is you have to decide for yourself if you can live with the hypothetical pros/cons of any system/process and go with what makes you a happy brewer. I haven't been disappointed in any of my beers because of the system I use and I'm sure you haven't either. It is fun to think about and talk about these different ideas, though.

 

[The Pol]

Much of it comes down to your own personal goals and what YOU want for YOUR system.

Some people may think a 20 minute step is fine and it works for them... I dont.

I dont like the idea of having 160F wort on top of my mash while the bottom is 145F, because I dont want a mash that I cannot quantify.

This is me... this is why I do infusions with the flip of one switch from my HLT to my MLT. This is the ONLY reason I built my sight gauges.

There are certain variables that I am not willing to accept... but they may be fine for someone else.

 

[Lil' Sparky]

I'm beginning to get the feeling that maybe you think using HERMS for step mashing is a bad idea...

 

[The Pol]

I'm beginning to get the feeling that maybe you think using HERMS for step mashing is a bad idea...

It is a bad idea for me...

What other see as suitable is thier view.

Look, I have been told here that my methods "wont work" enough to know, that is an ignorant statement on many levels.

"Wont work" for who? For you? For me? For the guy reading the thread who isnt posting?

I wont step with a HERMS, without using an infusion from the HLT. Luckily through practical useage of my system I was able to create thermodynamic equations to calculate the qty, temp and HLT heating times to make it possible.

Key words, practical useage. Theory is just that, it isnt fact. Even the facts can be disputed. For me the fact that it takes 20 minutes to step is too long, for the next guy, that same fact may be completely acceptable.

 

[Lil' Sparky]

Yep, I'm just about convinced now that you think it's a bad idea.

 

[The Pol]

Yep, I'm just about convinced now that you think it's a bad idea.

You arent reading what I write, I dont think.

I am NOT saying that. I dont like the variables involved.

You could just as easily "assume" that since I have a HERMS that I think it is a bad idea to do single infusion mashing in a cooler. Which is also false. I just dont like some of the varaibles... but I think it is great for some people.

They are the same... they work for some, they dont work for me.

You are trying to push me into a 100% YES or 100% NO, and it is not that simple, life never really is.

 

[Lil' Sparky]

No, I know what you're saying. I'm just being an ass and pushing your buttons. I getcha.

 

[The Pol]

I figured you did...

I mean to me a step is 10 minutes or less.

The next guy may define it as 20 minutes or less.

So if I say you cant step mash, the 20 minute dude will troll all over me saying that you can. When in fact we are saying the same thing, he just finds it acceptable in his system.

 

[Lil' Sparky]

And by the way, pushing your buttons is really easy.

 

[bull8042]

And by the way, pushing your buttons is really easy.

So you are saying The Pol has nice big buttons?

 

[bull8042]

So, considering I have a HERMS using a chillus and keggle MLT, did we finally decide that exceeding the desired MLT temp on the HEX exit was acceptable as long as it was within 10°F or so? I am having a little trouble grasping all of this and trying to work at the same time. (Pol, don't try this on your job!)
I can hold 154°F coming out of my HEX dead on, but the mash as a whole will never actually get to that temp. So I have thought about allowing 4 - 5° hotter temps at the HEX exit to try and get the mash closer to my desired temp...