HERMS / Automated HERMS Best Practices / Lessons Learned?

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biertourist

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I've been using my 3 tier system for a year now; I always knew that I wanted to upgrade eventually to HERMS so I have planned ahead slightly.

I'm looking for best (and worst) practices when designing/using a HERMS system; what have you learned from using your system that you would do differently or that you really like about it? What trade-offs should people be aware of and thinking about?

My system:
  • 20 Gallon electric HLT (giant kitchen pot style). The HLT has a sight glass, a dip tube, and a second ballvalve with a whirlpool fitting so that I can recirculate the water to keep the temp even and to heat slightly faster. I also put this recirculation fitting in knowing that it would aid heat transfer if I put my HERMS coil into the HLT. This vessel is currently uninsulated and my auber PID maintains temperature for me. My temp probe is installed into the bottom site glass fitting and is basically at the bottom of the vessel. (This certainly impacted it's accuracy fairly dramatically until I started whirlpooling while heating the HLT.)
  • 13 gallon double-walled, insulated stainless mashtun. Mashtun has a perforated false bottom with a high % open area; the width to height of the mash is 1:1 on a normal gravity 10 gallon batch and 2:1 on a normal gravity 5 gallon batch. The mashtun works GREAT for constantly recirculated mashing and holds a consistent temperature but it is NOT possible to apply any direct heat. My mashtun currently only has an analog temp gauge; it doesn't have a temp probe.
  • 15 Gallon Glaciertanks electric boil kettle. Boil kettle has a stainless mesh filter and a dip tube; the mesh filter keeps out almost all hop material and at least 50% of the trub but the dip tube has a small diameter and limits flow out of the boil kettle a bit. I have a spare 1" triclamp fitting in the kettle but I don't currently have whirlpool capability as I just can't find a triclamp whirlpool fitting or solution.

My plan is to take my current copper immersion cooler and install it into the HLT and use it as the HERMS coil.


Specific Items I'm Looking for Feedback On

  • Location for HERMS temp probes (mash exit, mash return, middle of mash????)
  • Is a second PID controller a must for a HERMS system? (one for HLT, one for HERMS/Mash?)
  • Increasing rate-of-temperature-rise during step mashing with HERMS. -The whole point of having a HERMS system for me is to enable step mashing; I already have a VERY well insulated mashtun so holding temps and avoiding heat loss is not an issue for my system. I want a fast rate-of-temp-rise so that I'm not leaving enzymes activate for longer than I want them activate and to make my brew day shorter. (No, I'm not interested in RIMS; YES I know about some of the new design and equipment improvements in RIMS systems; I'm sticking with HERMS.)
  • Placement of HERMS coil within the HLT -should I recoil my immersion chiller so that it is almost as wide as the HLT and is therefore fully under the water line with a smaller quantity of water in the HLT?
  • HLT liquid filling strategy. I normally brew 6.25 gallon batches so that I end up with only 5 gallons of very clear and trub and yeast-free beer in my keg; I have a 20 gallon HLT and can certainly overfill it so that the HERMS coils always remain covered with hot water and ready-to-step mash. This seems like it would be a good idea but I just don't have any experience with HERMS yet so I'm not sure. -I also definitely still want the ability to brew 10 gallon batches and would like to understand what that would look like on such a system; I think it means refilling and reheating the HLT after mashing in.
  • Immersion coil in HLT vs. Counterflow chiller (or even plate chiller) as heat exchanger. This one I'm really interested in but I haven't really been able to fully wrap my head around the pros and cons here. It definitely seems like the rate of temp rise could be much higher and I wouldn't have to heat so much extra water in the HLT with a counter flow exchanger vs. an immersion coil in the HLT. It certainly seems like a good CFC could be dual use for both the HERMS heat exchanger and chilling post-boil. (As long as the sanitization issues are addressed.)

Other considerations: On the boil side I really want to be able to chill rapidly outside of the kettle and return the cooled wort back to the kettle to drop the total volume below 140F as quickly as possible. I'm afraid that my kettle will pass too much crud (trub and hop) to continuously chill through my plate chiller so I'm considering pickup up a CFC anyway. I'm also afraid that a plate chiller would reduce flow way too much to be able to whirlpool and chill with a single pump. -I think a good CFC and whirlpool setup would enable me to whirlpool and continuously chill in the kettle and leave the break behind but I'm imagining that a good trub filter would help this whole workflow out...

-I've also evaluated putting the HERMS coil in a separate smaller insulated vessel that has it's own electric element and I see some of the significant advantages but I'm simply not interested in this option.


Help! There's SOOO many moving parts and trade-offs to consider. Unfortunately I'm thinking that the best solution for my system is probably going to be the uber expensive one. (CFC + trub filter + extra PID controller and use CFC both for HERMS heat exchange and chilling.)


Adam
 
On the subject of where to place the temp probes in a HERMS system, these are my current thoughts:
The HERMS-dedicated PID controller (I'm assuming that I'll need a 2nd one) should measure the temperature at the output of the HERMS coil/input into the mash in order to prevent the temp there from rising above 161 so that I don't kill my enzymes. -I can then use my analog thermometer in my mashtun to measure mash temp...

But maybe I don't need to actually monitor the temp there as it will simply be a function of the starting mash temp and the liquid in my HLT and as long as my HLT water doesn't rise above a certain point I don't have to worry about the output rising above 161...


-What do I actually have the PID controller DO as a result of the temp set point? -Just control the pump? (I don't have actuated ball valves and the signal from a pid couldn't proportionally control them anyway...)


I'll happily go read any relevant other HERMS threads but there are a LOT of hugely different HERMS systems out there that don't necessarily apply to my situation.


I appreciate any input even on single questions / design decisions here.


Adam
 
Hmm... From this other HERMS thread it sounds like I can just use my PID to MEASURE the Mash temp and have the output directed to my HLT element while the pump runs continuously.
https://www.homebrewtalk.com/f235/herms-system-build-424501/

I don't understand how the full workflow would work or how I would prevent the liquid out from the HERMS coil from going over 161 and killing my precious enzymes...

Also how would I reprogram / recalibrate my PID for switching between the two uses?



Here's how I'm roughly thinking the workflow might work so that someone can hopefully help find where my thinking is going astray:

For giggles let's say that my strike water temp needs to be 132F to dough-in at a protein rest temp of 122F. I fill my HLT with my strike water+ my sparge water + any extra water to ensure that the HERMS coil is fully submerged after I dough-in. I set my PID controller (which is controlling my HLT output and has the temp probe connected to my HLT) to 132F while I recirculate in the HLT (which my PID is calibrated for) and let it do its thing.

Next I dough in and start my 15 min protein rest timer (Hefe recipe). Then what? --I need the HLT water to get hotter if it's going to actually raise the temp of the mash after the protein rest is complete but I can't start recirculating and heating the HLT water right now or the temp in the mash will start rising... What do I actually set the temp of the HLT to to get ready for the next step? (My wild-ass guess is that I could raise the HLT up to as much as 180F quite safely under the assumption that the water exiting the coil would still be below 170F.)

Then after the 15 min protein rest, I start my mash/HERMS recirculation pump and disconnect the PID temp probe from the HLT and connect it to the mash temp probe and set it to the temperature of my next desired step (let's say a 149F saccrification temp) and let it recirculate until it reaches my next step. --Won't the PID freak out because it's now connected to a vessel / scenario that it's not calibrated for? How do I know that the temp just won't keep climbing in the HLT to the point that the liquid going through the HERMS coil isn't going above 164F and denaturing my amylases?
-HMM... Maybe the PID being calibrated or not doesn't matter in this scenario as it's still accurately measuring the temperature of the mash and I'm turning off the pump once the mash reaches the target temp. --This still leaves the issue of the wort exiting the HERMS coil possibly being overheated but if I'm measuring this with a stand-alone thermometer with an alarm condition set for say 164F (actually maybe 170F as the wort will only be heated this hot for a very brief amount of time), then I would be alerted to this condition...


Adam

(I'm guessing that this issue of disconnecting the PID from a vessel that it's been calibrated for and plugging it into another vessel is why 2 PIDs are recommended.)
 
Another question is how much do I open the ball valve on my pump output while recirculating through the HERMs? -If I open it too much I'll get a stuck mash; if I open it too little it will increase the temp of the wort coming out of the HERMS coil. My wild ass guess here is to open it as much as I can while avoiding a stuck mash (my super wide super high % open area mash FB should come to the rescue here) so that the temp on the HERMS coil output is lower.

Adam
 
Another question is how much do I open the ball valve on my pump output while recirculating through the HERMs? -If I open it too much I'll get a stuck mash; if I open it too little it will increase the temp of the wort coming out of the HERMS coil. My wild ass guess here is to open it as much as I can while avoiding a stuck mash (my super wide super high % open area mash FB should come to the rescue here) so that the temp on the HERMS coil output is lower.

Adam

I have a 20 gal blichmann with thier flase bottom for my mash tun. I usually start my recirc slow until the grain bed sets about 5 - 10 minutes then i can run open the valve completely open. My pump his march 809 with the 815 impeller. My HERMS coil is in a 2 gal cooler so my response time is fairly fast so I don't worry about temp of the output side of HERMS coil if i adjust the ball valve.
 
Rockytoptim,

Appreciate the feedback. The more I think about it, the part that goes through the HERMS coil will only get really hot briefly until it gets thrown back in the main batch where it should cool down pretty quickly too so I'm not going to worry about the HERMS coil output temp. (Although I will check it "for science".) ;)


Anyone have any ideas about any of the other issues?

Adam
 
For water into the HLT, I add my strike water, sparse water and a little extra. I hold back some that will be used to cover the coil to help cool the water down after I dough in. If you want the rest at 122 and you raise the temp to 132, you will have your mash gaining temperature until the HLT gets back to 122. So I solve that problem by adding in the rest of the water until it evens out. I don't have an exact method, I just take a guess at how much to hold back
 
My suggestions based on my setup which I find works well:

[*]Location for HERMS temp probes (mash exit, mash return, middle of mash????)

In process control systems that involve fluid recirculating, temperature monitoring is usually done in the plumbing instead of in the kettle. This helps avoid temperature misreads due to stratification (layering). This is not an issue in the Boil Kettle as the violent boiling action continuously stirs the wort to ensure an even temperature throughout the kettle.

Stratification is most likely to occur in the Mash/Lauter Tun. A temperature probe placed in the grain through the side of the kettle would only be measuring one location. You would not know when the entire grain bed is at the desired target temperature as it heats slowly from top to bottom. By placing the probe at the kettle output you ensure that the entire mash temperature is being monitored. For example, when you increase the Hot Liquor Tank temperature to 168F to perform a mash-out, the water in the Hot Liquor Tank will reach 168F before the grain in the Mash/Lauter Tun. It is only when the Mash/Lauter Tun also reads 168F that you know that the whole grain bed is at 168F. Placing the probe elsewhere would not provide us with this accuracy.

So in both the HLT and MLT I put the probes in the kettle output like this:

IMG_5215_2.jpg


The HLT output probe controls the HLT water temp. The MLT probe is for display only.

I used to have the the MLT probe at the HERMS coil output but that was redundant as that temp always matched the HLT probe temp.

[*]Is a second PID controller a must for a HERMS system? (one for HLT, one for HERMS/Mash?)
Not a must, but without a way to know the mash temp you'll never know when the step is done. So I have a PID for the MLT too which is display only (doesn't control anything).

[*]Increasing rate-of-temperature-rise during step mashing with HERMS. -The whole point of having a HERMS system for me is to enable step mashing; ...

More power in the HLT will let you step faster. Simple as that.

Figure out what rise times you want and then use these calcs to figure out the power you need:

http://www.brewheads.com/powerrequired.php
http://www.brewheads.com/rise.php

With 6.25 gallon batches I'm sure that 5500W would be more than adequate. I brew twice as large batches and am happy with my rise times.


[*] Placement of HERMS coil within the HLT -should I recoil my immersion chiller so that it is almost as wide as the HLT and is therefore fully under the water line with a smaller quantity of water in the HLT?

The coil should be as much under the water as possible to maximize heat transfer.

[*] HLT liquid filling strategy. I normally brew 6.25 gallon batches so that I end up with only 5 gallons of very clear and trub and yeast-free beer in my keg; I have a 20 gallon HLT and can certainly overfill it so that the HERMS coils always remain covered with hot water and ready-to-step mash. This seems like it would be a good idea but I just don't have any experience with HERMS yet so I'm not sure. -I also definitely still want the ability to brew 10 gallon batches and would like to understand what that would look like on such a system; I think it means refilling and reheating the HLT after mashing in.

I'm not sure there's a question in here?

[*]Immersion coil in HLT vs. Counterflow chiller (or even plate chiller) as heat exchanger.

Personal preference really, and it depends on your process.

I went with a CFC and specifically chose to not use an IM because:

- Inability to use a hop back: A hop back adds an extra punch of hop flavour and aroma that can't normally be achieved in the brew kettle alone. It is a small container that holds hops through which hot wort is passed immediately before it is cooled by the chiller, locking in the hop character. While mostly used in certain beer styles (most notably American Pale Ales and IPAs) we want to keep our options open.

- Wort is not chilled as rapidly: Because the entire wort volume is chilled at once it chills more slowly and spends more time in the temperature zone where it is more susceptible to infection. Slow cooling can also lead to excessive dimethyl sulfides (DMS) causing a 'cooked corn' taste and aroma in the beer.

- Slower: It takes longer to chill the same volume of wort from start to end.

I'm not a fan of plate chillers or anything that has tons of tiny crevices. I find them harder to clean.

Lots of questions... my advice is to keep reading!

Kal
 
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