HERMs Output Temp

[dye4me]

Recently i have installed a jaded style wort chiller for my brew stand. It worked so well i decided to ditch my direct fire burner for my tun and picked up a second pump to run water from HWT through the the outer jacket of the chiller and use it as a heat exchanger for my recirculating mash. Ive only used it once and it provided me with excellent consistency for holding mash temp. Although i monitored the mash temp, i paid no mind to the temp that the heat exchanger was warming the recirculated wort to. After my initial strike i raise my sparge in the HWT to 168f. i would assume with the efficiency of my chiller/heater, the wort is probably close to that temp once it leave the auto sparge. Is this too hot? What should be a maximum output temp from my herms?

 

[Dcpcooks]

It's been my experience that monitoring the wort after its gone through your herms is the way to go. Your mash temp will always lag behind your returning wort temp. If you focus on the wort temp you will raise your mash temp but you will avoid heating your wort higher than your intended temps.

If you crank the temp up to raise your mash temps you could be denaturing your enzymes with temps and that can reduce your extraction and efficiency.

I look at it as

Wort temp is #1
Mash temp is #2
HLT temp doesn't really matter #3

I hope this helps

 

[dye4me]

That's my thoughts as well, so what should I shoot for as the max output temp from my exchanger?

 

[day_trippr]

That's my thoughts as well, so what should I shoot for as the max output temp from my exchanger?

That will depend on your target mash temperature - which can vary with style and recipe...

Cheers!

 

[Tiber_Brew]

It's been my experience that monitoring the wort after its gone through your herms is the way to go. Your mash temp will always lag behind your returning wort temp. If you focus on the wort temp you will raise your mash temp but you will avoid heating your wort higher than your intended temps.

If you crank the temp up to raise your mash temps you could be denaturing your enzymes with temps and that can reduce your extraction and efficiency.

I look at it as

Wort temp is #1
Mash temp is #2
HLT temp doesn't really matter #3

I hope this helps

I happen to disagree. Here's why:

1. It takes longer to denature enzymes than the short time that the small volume of wort spends in the heat exchanger (HEX), and a far higher temperature than that which occurs in the HEX.
2. The temperature of the enzymes that are in contact with the starches (in the mash) counts more than the temperature of the wort not in contact with the starches (in the HEX), since contact with starches is where the actual conversion takes place.

In order to account for heat losses between the HEX and my mash (and that of the MLT itself), I set my HLT (in which my HERMS coil sits) to a slightly higher temp than I want my main mash to be. My specific temperature delta is 4F, and this will vary slightly from system to system. I monitor my mash temp with a probe in the MLT. That is what I count my mash temperature to actually be, and the temperature at which the enzymes are doing their work.

That's how I understand it. If anyone can show that this is incorrect, I'm interested in hearing it.

 

[stevehaun]

Tiber Brew, your way will make good beer but it is not ideal from a temperature control standpoint. IMHO, it makes far more sense to actually control the temp of the wort as it returns to the top of the mash than to extrapolate it. You can then measure the temp of the mash and the temp of the wort leaving the bottom of the mash tun. Why do you want to know the temperature of the water in your HLT?? Because from that temp you can extrapolate (educated guess) the temperature of the wort returning to the top of the mash. Why not simply control the temp of the wort instead of extrapolating?

 

[Tiber_Brew]

Tiber Brew, your way will make good beer but it is not ideal from a temperature control standpoint.

I would say the exact same about your method, no offense. While my PID is not controlling my mash temp via a wort temp feedback loop, I'm maintaining a more critical temperature - that of my actual mash. This is where conversion takes place, and this is where the temperature of the enzymes is most important. Would you not agree that your mash temperature is the temperature of your mash? Why would anyone argue that your mash temp is that of the wort leaving the HEX?? Am I interpreting your argument incorrectly?

It appears we have two items in point here: 1. what is considered the mash temperature? 2. How best to control that temperature using a PID controlled HERMS?

1. I think it's clear that your mash temperature is that of your actual mash. I don't see how anyone could argue this. The mash is where hot water and enzymes convert starches into sugars.
2. This could be debatable, and there is more than one way to do it. Both the method mentioned previously in this thread and the method I advocate have potential to control the mash temperature. My argument is that, with a constant known ΔT between equilibrium mash temperature and HLT temperatures, applying that delta to the HEX (in the HLT in the case of HERMS) easily and accurately achieves desired mash temperature.

My temperature delta is a constant 4 degrees F between the mash temp at equilibrium and that of my HLT. All my temp probes are calibrated using a NIST certified thermometer, so I know this 4F delta to be accurate. There are losses in the fittings, pump, plumbing, and the MLT material itself (stainless keg). This adds up to 4F ΔT for my system, and others may vary +/- 2F or so by my estimation. Every single time I brew, I can set the HLT to 4F above my desired mash temp and achieve it. When not accounting for these losses, your mash temperature will be below that of your target, which would be the case if you're only controlling the wort temp exiting the HEX.

IMHO, it makes far more sense to actually control the temp of the wort as it returns to the top of the mash than to extrapolate it.

Why, though? That doesn't make sense to me based on principals of mashing science. Why concern yourself with the temperature of wort that carries enzymes that are not in contact with your mash grains? This comes back to point #1. Also, there is no extrapolation involved in my process. I know the temperature of the wort leaving the HEX (equal to HLT temp), and I know the temperature of the mash being converted via two probes in the MLT. It takes 20 minutes to find the losses of your particular system, then set your HLT temp based on your known ΔT there on. Now you're controlling the temperature of your mash, not some wort in a HEX.

You can then measure the temp of the mash and the temp of the wort leaving the bottom of the mash tun. Why do you want to know the temperature of the water in your HLT?? Because from that temp you can extrapolate (educated guess) the temperature of the wort returning to the top of the mash. Why not simply control the temp of the wort instead of extrapolating?

Again, no extrapolation required. And why would I care what the temperature of the wort returning to the mash is? That isn't my mash temp (again, point #1). The wort returning to the top of the mash doesn't stay at that temp for more than two seconds as it converges into equilibrium. It is this equilibrium that we call the mash temp. Like I said, I know the temp of my wort leaving the HEX based on the temp of the HLT that I set. Besides that, what the brewer needs to be concerned with is the temperature of the mash, not the small amount of heated liquid entering it. I have two temp probes in my MLT; one towards the top of the tun, and one towards the bottom. When ramping, the top one reads about 4F higher than the bottom one. Once equilibrium is reached (rest temperature), they read the exact same.

Think of it this way; you are adding heat to your mash to maintain a temperature that you desire for conversion. There are many ways to do this, but they all involve applying heat to material in contact with the mash (this, of course, does not apply to insulated single infusion tuns). Measuring the temperature of the heated material at the high end of the gradient is pointless, since you are concerned with the conversion occurring in the mash itself. Why would a HERMS be any different? It's not. If all your conversion were taking place within the wort inside the HEX, then that would be the process point for which I would control. This is not the case, however, so the point of control necessary happens to be where the overwhelming majority of the conversion is taking place - the mash tun. Point being: if you are only controlling the temperature of your wort as it leaves the HEX, you are actually mashing several degrees shy of your desired mash temp.

Make sense? Thoughts? Thanks for hearing out my long winded argument!

 

[stevehaun]

Let me preface this by saying that I am sure your system has excellent mash temp control and makes great beer.

But, no, I really don't follow your logic. I don't understand your leap from controlling the HLT temp to controlling your mash temp. Yes, I get that you have a 4F delta between your HLT and the mash temp and that this is very consistent in your system. In my system, my controller thermocouple sits right outside my mash tun. In my system, I set my controller 4F higher than my desired mash temp. I then measure my mash temp and the temp of the wort as it leaves the mash tun. I do not understand why you think controlling your HLT temp is a more direct way of controlling mash temp. You are not controlling mash temp any more directly than I am. In fact, I would argue that your approach is more indirect. The only way to be more direct than my approach is to put the controller thermocouple in the mash itself.

 

[Tiber_Brew]

Let me preface this by saying that I am sure your system has excellent mash temp control and makes great beer.

Thanks. With 6 years of (award winning) brewing on my eHERMS, it would appear so.

But, no, I really don't follow your logic. I don't understand your leap from controlling the HLT temp to controlling your mash temp. Yes, I get that you have a 4F delta between your HLT and the mash temp and that this is very consistent in your system.

Then what about this is confusing for you? Read that last sentence again.

In my system, my controller thermocouple sits right outside my mash tun. In my system, I set my controller 4F higher than my desired mash temp. I then measure my mash temp and the temp of the wort as it leaves the mash tun.

Now wait a minute. I thought you were advocating controlling the wort temp as it exits the HEX, as Dcpcooks described above.

If you're controlling your HLT PID via the wort temp as it leaves the MLT, then that's totally different from what I thought you were advocating here. Dcpcooks was advising OP to put the controlling temp probe at the HEX output, which is what I disagreed with, and the method that I thought you were defending here. It appears that our processes aren't that different after all. Even your ΔT is the same.

Your particular method is much better than the HEX output method mentioned previously in this thread. In fact it's 90% the same as what I'm doing. I gotta say, I still don't prefer it over manually entering HLT temp, though. My reasons are simple, and we're speaking about preferences at this point, but hear me out if you want to understand this better. Look, ΔT between mash temp at equilibrium and the HLT is known. There's no point in using PID algorithms to find the right HLT temp when you already know the right HLT temp based on the ΔT of your system. So, we've got a known ΔT, and a known HLT temperature required in order to maintain your desired mash temperature. Well, you know this delta, why not just enter it? Tell the HLT what temp it should be, rather than asking a PID to figure it out! Why on earth would you want to leave it up to a PID to "find" this delta every time you brew? The only reason I could think of would be if you brew in a garage or somewhere seasonal and your losses vary from batch to batch, which would cause your ΔT to vary. Make sense yet?

I also know the exact temperature of the sparge water (and keep that temp PID controlled) throughout the lautering process. The same cannot be said for your method.

I do not understand why you think controlling your HLT temp is a more direct way of controlling mash temp. You are not controlling mash temp any more directly than I am. In fact, I would argue that your approach is more indirect.

That's not really a true statement, as I explained above. Listen, we are both ensuring accurate mash temps at equilibrium, right? But your setup has looser control attributable to PID lag (which, of course, is only applicable during ramping, so this isn't a huge deal). Now that I know that you are not using HEX output as your PID feedback, but instead your MLT output, I don't really have a huge objection to that. As you said, you set your temp to 4F above your desired mash. My delta happens to be exactly the same. We are basically doing the exact same process; we are just controlling it slightly different. I manually set my HLT PID to 4F above desired mash temp and quickly and accurately reach my temps, while you on the other hand, are asking your PID to use MLT exit temp as its feedback, which doesn't afford you as "tight" of a control, but will still accurately maintain your mash temp. Once temperature is reached on both our setups, both are plenty accurate. Am I making sense to you yet?

The only way to be more direct than my approach is to put the controller thermocouple in the mash itself.

Well, again not true. Wrong direction. You're too fixated on the "controlling" aspect and terminology. A PID isn't always the best way to control a system parameter, in fact it actually puts you at an ever so slight disadvantage over manually entering the HLT temp when you're ramping your mash (so long as your ΔT is constant). Again, not a huge deal. Listen, on one hand you have a known value, and you can enter it to maintain a process parameter. On the other, you have a known value, but you still ask a PID to figure that value out each time you brew...to maintain a process parameter. See? Both methods work. I like mine better because I'm a process oriented engineer turned brewer/brewing adviser. I'm not telling you that your method is wrong. I just have the control I need from my system to control the process the way I want. It works very well and I've been happy with it since I built it in 2010.

Anyway, I've used up my patience on this topic for now. If you have specific questions, shoot away. Otherwise, we can get back to brewing our (slightly) different ways. Cheers, bud.

 

[dshepard]

Tiber Brew et al this is an interesting thread. On my HERMS system I have a 3-way valve I use to bypass the HEX as needed. However this requires me to "babysit" my mash as I have to fiddle with the valve to maintain the temperature exiting the HEX. (ignore the discussion above for a minute, this is the way I have been doing it for 15 years). I am always open to new ideas I like the idea of setting the HLT to a 4 degree delta (or whatever it would be in my case after trial and error) and running the wort fully to the HEX. I am going to give this a try as I would now not have to be the manual PID controlling the bypass valve (I don't have a controller, just myself operating the valve).

I have a question for Tiber Brew. At what rate are you able to ramp up to the next rest? I may have to get a larger burner, because now I would have to raise the both the mass in my HLT and the Mash at the same time during a step rise. Currently because I have a bypass valve I can start raising the HLT before my step raise. For what it is worth, I brew 10 gallon batches and probably have 10-12 gallons in my HLT for sparging and cleanup and generally mash approximately 20+ lbs of grain at 1.50 quarts/lb.

 

[Tiber_Brew]

Tiber Brew et al this is an interesting thread. On my HERMS system I have a 3-way valve I use to bypass the HEX as needed. However this requires me to "babysit" my mash as I have to fiddle with the valve to maintain the temperature exiting the HEX. (ignore the discussion above for a minute, this is the way I have been doing it for 15 years). I am always open to new ideas I like the idea of setting the HLT to a 4 degree delta (or whatever it would be in my case after trial and error) and running the wort fully to the HEX. I am going to give this a try as I would now not have to be the manual PID controlling the bypass valve (I don't have a controller, just myself operating the valve).

Sounds like you were using a monotonous method! Let's see if we can't improve on that...

I have a question for Tiber Brew. At what rate are you able to ramp up to the next rest?

Almost exactly 1°F/minute. The beginning and end of the ramp won't be linear and will take a little longer than 1F/min, though. It will of course depend on on the temperature difference between your HLT setting and your current mash temp. For example, if my mash is resting at 140F and I want to hit 150F, I set my HLT from 144F to 154F, and about 10 minutes after the HLT PID hits 100% duty rate, my mash is 150F. On the other hand, if my mash is resting at 150F and want to hit 155F, I set my HLT from 154F to 159F. It still takes about 10 minutes for a 5F increase. The difference between the two ramps is the ΔT on the first ramp is 10F, but only 5F for the second. Thermodynamics tells us that the equation for conductive heat transfer is Q=mcΔT. Where Q is the heat transfer rate, m is the mass, c is the specific heat of the material, and ΔT is the difference in temperature between the two materials. Hence, when ΔT increases, the heat transfer rate increases (directly proportional).

Anyway, short answer long... When I'm making a ramp of 10F or more, I get about 1 degree F per minute. Here is an example of a snapshot from the data collected from an actual brew day of mine. I collect this and all sorts of data each brew day, and it's quite consistent:

I may have to get a larger burner, because now I would have to raise the both the mass in my HLT and the Mash at the same time during a step rise. Currently because I have a bypass valve I can start raising the HLT before my step raise. For what it is worth, I brew 10 gallon batches and probably have 10-12 gallons in my HLT for sparging and cleanup and generally mash approximately 20+ lbs of grain at 1.50 quarts/lb.

Here's my setup: all vessels are stainless half barrel kegs, 5500W stainless element in the HLT, 4500W in the BK. HLT and BK are both PID controlled via RTD probes in their respective vessels. My HERMS HEX sits in my HLT, which is filled with 15 gallons of treated water. MLT has a two stage false bottom with a dip tube coming through the center. MLT has two temp probes protruding 3" through sidewall - one about half way up the tank, one about a third the way up. I brew 11 gallon batches, with anywhere from 13 lbs to 30 lbs, all at 1.50 qt/lb. So, I think we're close enough where I can help you. How are you measuring and maintaining your HLT temp, by the way?

Try this:

1. Have your HLT set at 4F higher than your desired mash temp. Your actual delta may be different, but that's OK for the time being.
2. Dough-in as usual, somewhere between 140F-150F. Note the initial mash temperature.
3. Turn on your wort recirculation through the HEX (make sure it's not too fast or too slow) and keep it recirculating at the same rate throughout the entire mash.
4. Meanwhile keep your HLT at the same temperature while recirculating, and hold for at least for 20 minutes.
5. Note your mash temperature as it's changing. And by mash temperature, we mean the temperature of your actual mash, where the grain and wort sits in the mash tun.
6. When your mash temp has stopped changing, write that value down. Now compare it to the temperature of your HLT. What is the difference? That will be your mash system ΔT.
7. Next, you'll step the HLT up 10°F above its current temp. Make sure to maintain that HLT temp. Now note the rate that the mash temp increases, and where it stops. It should stop at [HLT Temp - ΔT].
8. Come time for lautering, set the HLT to [168F + ΔT], which should be somewhere around 171F-175F depending on the losses in your particular setup. This will bring your mash up to mashout temps, then hold for 5-10 minutes.
9. Divert your wort to your boil kettle, and hook up your hot liquor out the HLT to the pump, from pump to HEX input, HEX output to sparge manifold. This will set you up for fly sparging. Make sure your HLT isn't set over 175F at this point to avoid bringing the mash temp into tannin territory.

That's it. Hope this helps. Let me know if you have questions.

 

[dshepard]

I did some testing yesterday using just water on my system. I typically mash in at 104 then raise to 145. I set my HLT to 149 and set the timer. It only took 21 minutes for the HLT to go from 106 to 149, not bad. However it took 56 minutes for the mash to reach 145. After a slow start it started to raise relatively quick, but then towards the end it was taking forever for the last 5 or so degrees. I think I am going to go back to my regular method of having the HLT about 15-20 degrees higher than my target mash temp. I am able to raise the mash in around 15-20 minutes using a 2.5 gallon infusion to boost the temp. The remaining steps I just use the HERMS. With my method of using the bypass valve, I can have the HLT at the next rest before I start raising the mash temp. I keep my HLT 15-20 degrees higher during the ramp. Once my mash reaches temp (Probe about mid way in the mash) I can start letting the HLT stabilize near my Mash setpoint (similar to what you do) and use the bypass valve if needed. It is really not bad as it keeps me hands on with my mash which I enjoy.

 

[dshepard]

To the original poster I hope we didn't get too far off topic. I think what it does show though is that you will have to get know your system.

 

[Tiber_Brew]

I did some testing yesterday using just water on my system. I typically mash in at 104 then raise to 145. I set my HLT to 149 and set the timer. It only took 21 minutes for the HLT to go from 106 to 149, not bad. However it took 56 minutes for the mash to reach 145. After a slow start it started to raise relatively quick, but then towards the end it was taking forever for the last 5 or so degrees. I think I am going to go back to my regular method of having the HLT about 15-20 degrees higher than my target mash temp. I am able to raise the mash in around 15-20 minutes using a 2.5 gallon infusion to boost the temp. The remaining steps I just use the HERMS. With my method of using the bypass valve, I can have the HLT at the next rest before I start raising the mash temp. I keep my HLT 15-20 degrees higher during the ramp. Once my mash reaches temp (Probe about mid way in the mash) I can start letting the HLT stabilize near my Mash setpoint (similar to what you do) and use the bypass valve if needed. It is really not bad as it keeps me hands on with my mash which I enjoy.

I'm surprised that your HEX is so inefficient. We could possibly work that out to improve upon it, but perhaps that would be best for another thread. Otherwise, if you like your setup and process, by all means, stick to it!

 

[Dcpcooks]

I happen to disagree. Here's why:

1. It takes longer to denature enzymes than the short time that the small volume of wort spends in the heat exchanger (HEX), and a far higher temperature than that which occurs in the HEX.
2. The temperature of the enzymes that are in contact with the starches (in the mash) counts more than the temperature of the wort not in contact with the starches (in the HEX), since contact with starches is where the actual conversion takes place.

In order to account for heat losses between the HEX and my mash (and that of the MLT itself), I set my HLT (in which my HERMS coil sits) to a slightly higher temp than I want my main mash to be. My specific temperature delta is 4F, and this will vary slightly from system to system. I monitor my mash temp with a probe in the MLT. That is what I count my mash temperature to actually be, and the temperature at which the enzymes are doing their work.

That's how I understand it. If anyone can show that this is incorrect, I'm interested in hearing it.

I must disagree.

Blichmann and Sabco both monitor wort temps. I have blichmann gear and I just called Sabco to ask how they monitor temps. Both monitor wort not the mash.
Sabco said they monitor wort temps because it removes the risk of denaturing enzymes.

 

[Tiber_Brew]

I must disagree.

Blichmann and Sabco both monitor wort temps. I have blichmann gear and I just called Sabco to ask how they monitor temps. Both monitor wort not the mash.
Sabco said they monitor wort temps because it removes the risk of denaturing enzymes.

There is no risk of denaturing enzymes with a HERMS. I believe I've been very clear on this with well supported arguments. I don't know what else to tell you. Re-read everything I've said in this thread if you're still not clear on it. If you want to follow the Kal method (as does Blichmann and Sabco apparently), that's fine. I'm not saying it's wrong or that it won't make good beer. It's just not optimizing the process where it counts most. That's all.

Cheers

 

[augiedoggy]

For what its worth...
I have also read that momentary wort exposure to higher temps such as a rims or herms coil is not long enough to denature even the enzymes that may be in that wort...

This is kind of an old argument along with those who control thier rims with a sensor at the mash output which I dont think is very good practice.

controlling the rims or hlt (or heat source) temp directly is always safer since you may experience varing degrees of flow through the rims or herms coil which cannot instantly be compensated for and the result would be overshooting temps until things catch up and correct themselves. This is an even bigger issue with rims where there is a large time delay between the wort temp exiting the rims tube and the output of the MT...

 

[orangehero]

The malt diastase enzymes are dissolved into the liquid wort. If you denature them in the HEX it doesn't matter what temperature the mash is. Whether enough are denatured while you are continuously pumping them through a "hot" HEX is debatable over the time course of a regular mash. At mash temps the enzymes are already being denatured at some rate.

 

[Tiber_Brew]

The malt diastase enzymes are dissolved into the liquid wort. If you denature them in the HEX it doesn't matter what temperature the mash is. Whether enough are denatured while going through a "hot" HEX is debatable over the time course of a regular mash. At mash temps the enzymes are already being denatured at some rate.

There is no way you're denaturing enzymes to any noticeable or detrimental effect, or in any way that isn't already occurring in the mash, when heating the wort 4°F more in a HERMS HEX. A brief 4°F increase isn't "hot," by the way. The "denaturing enzymes" argument is invalid and a flat out moot point. Beside this, even if enzyme denaturation was a concern (which it isn't), with the diastatic power of today's malts in the 140-160 range, there's no threat to full and proper starch conversion with a HEX operated mash. The proof is in the final product, which I'd happily offer a pint of to anyone questioning this.

 

[orangehero]

The point isn't necessarily denaturing but the kinetics of the mash reactions. Keeping a mash and wort precisely at 150°F is going to be different than constantly running wort through a HEX at 4°F higher. So when you say you employed a 150°F mash temp, that may mean someone with a different system may need to use a higher temp to get similar results. I agree though, probably a moot point.

Both methods work just fine with a properly tuned PID controller. In one case you are controlling the load directly when you control HEX output temp. In the other case you are controlling the HLT temp but know what your losses are and can manually adjust the offset while monitoring the mash tun temp. The main benefit of PID control is precision and repeatability.

 

[Tiber_Brew]

Keeping a mash and wort precisely at 150°F is going to be different than constantly running wort through a HEX at 4°F higher. So when you say you employed a 150°F mash temp, that may mean someone with a different system may need to use a higher temp to get similar results.

That's absolutely not true. If I measure my mash to be 150F, then my mash is 150F. Period. How can anyone argue that? Maintaining that temp via a 4F delta in the HEX makes no difference. There's nothing happening to the starches in the HEX, and there's no detriment to enzymatic activity resulting from the HEX. That's like arguing that a beer that was mashed in a gas fired mash tun wasn't really mashed at 150F because the mash adjacent to the tun walls was hotter than the rest.

Both methods work just fine with a properly tuned PID controller. In one case you are controlling the load directly when you control HEX output temp. In the other case you are controlling the HLT temp but know what your losses are and can manually adjust the offset while monitoring the mash tun temp.

As I've said before, you are not controlling the mash temp when you control the HEX output temp. You are controlling the temperature of a small volume of wort that quickly decreases in temperature when it enters the mash. Besides, the HEX output temp is equal to the HLT temp, and mine remains constant at a single mash rest since I tell the HLT at which temperature to remain. So my method is more stable just with that fact alone. If for some reason I wanted to know the temperature of my wort as it leaves the HEX, I just look at the HLT temp, which sits exactly where I set it to.

The main benefit of PID control is precision and repeatability.

Again, not true. The more losses between PID feedback (temp of wort outside the mash) and the controlled element (HLT water), the more lag and risk of overshooting mash temp (temp of the actual mash inside the MLT). (Keep in mind the PID itself won't read an overshoot; you have to measure your mash to see the oscillation.) You are drawing a much wider system boundary and asking a PID to "figure out" the variances and losses within that large system, rather than keeping a simple tight control over the process. Please read the thread again. I'd rather not keep repeating myself. I believe I've explained this quite thoroughly, and @augiedoggy added as well:

controlling the rims or HLT (or heat source) temp directly is always safer since you may experience varying degrees of flow through the rims or herms coil which cannot instantly be compensated for and the result would be overshooting temps until things catch up and correct themselves. This is an even bigger issue with rims where there is a large time delay between the wort temp exiting the rims tube and the output of the MT...

There's an unfounded love affair with the concept of using a PID to control the mash temp amongst homebrewers. Yeah, PIDs are neat devices and certainly can play a helpful role in brewing, but using them for something that a basic ΔT compensation would work much better for is frankly not only overcomplicating something simple, but costing you optimum stability in mash temp control. "But it's more precise!" or "that's what Blichmann does!" aren't valid arguments. You can choose whether to hold on to your notion of mash control or not. I'm just telling you the facts.

 

[orangehero]

The system you are describe has nothing to do with whether a PID algorithm is used. It will still help maintain a steady temperature in the HLT and prevent overshoot when ramping temperature. Obviously you can have an improperly tuned algorithm in either case.

You can use a regular on/off controller but it will inherently have more oscillation than a properly tuned PID controller.

 

[day_trippr]

I'm interested in how the mash temperature can be DIRECTLY monitored by a fixed probe with complete assurance of its accuracy...

Cheers!

 

[Tiber_Brew]

The system you are describe has nothing to do with whether a PID algorithm is used. It will still help maintain a steady temperature in the HLT and prevent overshoot when ramping temperature. Obviously you can have an improperly tuned algorithm in either case.

Yes, this does have everything to do with whether a PID algorithm is used. I'm not using a PID algorithm to control my mash temp; I'm using one to control my HLT temp. And, since there is a steady and consistent temperature difference between the HEX temp and my mash temp, I'm maintaining a more controlled mash temp than any setup using a PID getting its feedback from wort. When using PID feedback from wort to control the HLT temp, there will be non-zero amount of oscillation in the mash itself.

You can use a regular on/off controller but it will inherently have more oscillation than a properly tuned PID controller.

Again, you are confused here. Have I not explained my setup and process well enough? Serious question. I don't use on/off controllers for anything. A PID controls my HLT temperature, based on the temp of the hot liquor in the HLT itself. Thus, maintaining a constant temperature in the HLT, therefore the HEX, and therefore my mash temp. Everything remains at a constant equilibrium during a rest without having to overcomplicate things with PID input from the wort, and literally without any oscillation.

 

[Tiber_Brew]

I'm interested in how the mash temperature can be DIRECTLY monitored by a fixed probe with complete assurance of its accuracy...

Simple. Two NIST certified calibrated temp probes in the mash, both reading equal to each other at equilibrium, and both reading exactly the same ΔT from the HLT each and every time. This is how the mash temp is measured on commercial systems that I've used as well.

 

[Dcpcooks]

That's my thoughts as well, so what should I shoot for as the max output temp from my exchanger?

I shoot for my target mash temp. I think flow rate and the size of your coil is an important factor relative to heat transfer. A high flow rate and a small coil can result in an inefficient heat transfer and add time to the process. If you crank your HLT to 160 to help raise your mash temp faster you'll denature all your b amylase enzymes as they are destroyed above 155.

 

[orangehero]

There's nothing happening to the starches in the HEX

Of course there is. The wort is a solution of sugars and enzymes.

As I've said before, you are not controlling the mash temp when you control the HEX output temp. You are controlling the temperature of a small volume of wort that quickly decreases in temperature when it enters the mash.

Assuming constant recirculation have you found that the full mash doesn't reach the temp of the fluid returning directly to it?

 

[Tiber_Brew]

Of course there is. The wort is a solution of sugars and enzymes.

Think about what you're saying. The point of a mash is to convert starches to sugars. The starches are in the grist, the enzymes are in the wort (shortly after dough-in). When the portion of the wort carrying enzymes is not in contact with the grist (in the HEX), those enzymes are not doing any conversion. It does not matter if there are already sugars dissolved in the wort when it's being heated slightly in the HEX. When hot water comes in contact with gelatinized starches in the mash, they dissolve as they are converted to sugars by amylase enzymes. The wort that is in contact with the grist is converting starches at the temperature at which it sits in the grist. This is what we call the "mash temperature."

Assuming constant recirculation have you found that the full mash doesn't reach the temp of the fluid returning directly to it?

Yes! I know this by measuring (direct observation), as well as this concept following the basic laws of thermodynamics. This is the reason that the HLT needs to be warmer than the desired mash temp. At a dynamic equilibrium, the MLT, fittings, plumbing, and pump all lose a total of about 4F, but the HEX is adding 4F to the system during constant recirculation. Bam! Stable mash temperature! This is also why I still strongly disagree with Dcpcooks above in his advice to OP.

 

[orangehero]

What kind of flow rate are you using through the HEX?

 

[Dcpcooks]

Tiber_brew. I like your tenacity!
Yes we want to measure our mash temp. Yes we want to achieve conversion at our "desired mash temp" it's what we strive for.

I think we get to the same place at the same time. If my wort is returning to my mash at my target temp my mash will follow. Yes there is a delta we need to consider.

You have a custom system that (correct me if I'm wrong you built from scratch. Your a smart guy with some sort of engineering background. I built my system around a chef's knowledge which is only concerned with time and temperature. When I built mine I didn't even know what a HERMS system was! I only wanted to control my wort temp which would raise my mash temp accordingly with time. There is no difference in time between our set ups. We both throw BTU's at our HLT to manage temps.

You set your HLT temp to your desired mash temp vie the HLT and wait for your mash temp to reach your set point.

I set my wort temp via the HLT and wait for my mash to reach its set point.

I agree your actual mash temp is a better way to gauge timing especially if we're going to ramp up through rests. You know when your mash is at a certain temp. ( but I bet you've cheated and started your next ramp once the top of the bed hit your desired temp, knowing your lag time and your wife was wanting you to do something else)

My only challenge is you have a custom set up and a skill set that may be challenging to replicate. I'm sure you make great beer and I'd love to try some. I make beer that I'm proud to share as well. I think we need to make this accessible to ambitious Brewers as they move through the process. Your right for your system and I'm right for my system. One of the great things about this obsession is we get to build a system that's ours. Made with our own hands.

You should write up an article on how you built your system for the site.

Cheers!



Let's make it easy for the new guys!