I need a Herms Expert

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Schlomo

Schlomo

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So, i made a herms setup, 3 tier, all that.

My problem is that even after running auto tune, i will over shoot every single time, and not even by a little, by alot.

I think i know my problem is that my herms coil is too small diameter as I only used some scrap copper i had lying around.

Can a herms expert help me pinpoint what I need to change to get better mash temp? I'm really not sure where to start.. but I'm running an 120v system.
 
A little more information would be beneficial for people to help. What kind of controller are you using? What is the diameter of the coil and the overall length? Where are you measuring the temperature for the controller? Was your process for autotune the same as a normal mash but with out the grain; same temp range? Also what is your process for mashing in with the system?
 
Other questions - what temperatures do you normally mash at / what temp did you auto-tune to? Do you run a pump or some other means to recirculate the HLT water? Was that pump or recirculation running when the auto-tune was run?

Where we're going with this - auto-tune SHOULD work, but you need to make sure you auto-tune with basically the exact same setup and configuration as you would be running things during a brew day.
 
I used 120v, for the HLT I only have 2000w to heat that water, but its a smaller HLT (5 gallon SS pot). The Herms coil is small (1/4" ID) 25' long. I auto tuned starting at 100F water up to mash temp of 154F. It took a while but it ended up working.

I do NOT have a HLT recirc pump. I use a Mypin TA4 PID.

I'm thinking either I have too little power to the HLT, or I have too small a Herms Coil. I know I need to upgrade, just need the money.
 
Schlomo said:
I used 120v, for the HLT I only have 2000w to heat that water, but its a smaller HLT (5 gallon SS pot). The Herms coil is small (1/4" ID) 25' long. I auto tuned starting at 100F water up to mash temp of 154F. It took a while but it ended up working.

I do NOT have a HLT recirc pump. I use a Mypin TA4 PID.

I'm thinking either I have too little power to the HLT, or I have too small a Herms Coil. I know I need to upgrade, just need the money.
Click to expand...

You also need to recirculate or stir the HLT water. That makes a HUGE difference!
 
Like Yooper says recirculating the HLT water can make a huge difference. But I think you can also get around that depending on how your process for mashing in works. I only have 1 pump so I only recirc the mash, and at times I wish I had 2, but I have manged. I think the main focus for me is letting it hit equilibrium before mash in. For my strike temp calculation I do it as if my 10 gallons in the HLT are part of the calc. So rather then lets say 2 gallons for mash in I calculate the strike temp as if I had 12 gallons of water in the mash tun. I let it recirculate tell it hits this temp and is holding it. Usually overshoots initially because I am not recirculating HLT. Then I mash in and keep an eye on it. Every once in awhile I will set the mash temp a bit low if I think it will overshoot, but rarely need to. I find the only time I have big overshoot is if I have a big temp change, so heating cold water up to strike temperature. But my strike temp to mash temp is close enough my overshoot is negligible.

Also my herms coil is the same diameter and probable less length so I wouldn't worry about that. And 2000W seems plenty for 5 gallon HLT, at least in terms of your current problems.
 
Yooper said:
You also need to recirculate or stir the HLT water. That makes a HUGE difference!
Click to expand...

I just pulled the trigger on a second pump to recirc HLT water.

Hope that will help. Next test will be getting a 1/2" SS herms coil, but i'll have to modify some stuff for that.
 
the problem is that autotune isnt all that great.

the first thing you can do is turn the "D" in P,I,D to zero/off. the derivative setting isnt really needed with so much thermal mass (5-10 gallons of water) and so little input energy. it is useful in ovens/kilns where the thermal mass of the air is 1/100,000th that of our brew systems. the water temperature just cant "move" fast enough to require a derivative calculation.

then, without going into a course on PID theory, "P" should be relativly low. mine is set to around 5% or less. this will make the controller respond to temperature changes very quickly. in an oven/kiln, you would set this higher, so that it would smooth out smaller measurement variations. however in a brew setting, the measurement variation of one or two degrees should be cause for the controller to act.

"I" - you can look at it as the average of the last "I"-amount of seconds that the controller should take into account. mine is somewhere around 15-25 seconds. again, this is low because the temperature swings in our system are also relatively very low.

so before you buy anything, try these settings and see if that clears up your issues

P = 5 (try anywhere from 2-10)
I = 20 (try anywhere from 10-30)
D = 0


circulating the HLT water will certainly make things more consistent, but i would bet your problems have little to do with length of the coil or other things, and more to do with autotune just getting it wrong.
 
audger said:
the problem is that autotune isnt all that great.

the first thing you can do is turn the "D" in P,I,D to zero/off. the derivative setting isnt really needed with so much thermal mass (5-10 gallons of water) and so little input energy. it is useful in ovens/kilns where the thermal mass of the air is 1/100,000th that of our brew systems. the water temperature just cant "move" fast enough to require a derivative calculation.

then, without going into a course on PID theory, "P" should be relativly low. mine is set to around 5% or less. this will make the controller respond to temperature changes very quickly. in an oven/kiln, you would set this higher, so that it would smooth out smaller measurement variations. however in a brew setting, the measurement variation of one or two degrees should be cause for the controller to act.

"I" - you can look at it as the average of the last "I"-amount of seconds that the controller should take into account. mine is somewhere around 15-25 seconds. again, this is low because the temperature swings in our system are also relatively very low.

so before you buy anything, try these settings and see if that clears up your issues

P = 5 (try anywhere from 2-10)
I = 20 (try anywhere from 10-30)
D = 0


circulating the HLT water will certainly make things more consistent, but i would bet your problems have little to do with length of the coil or other things, and more to do with autotune just getting it wrong.
Click to expand...



Just checked what my Auto tune set it to. P - 1.2, I - 1052, D - 350.

Makes sense why it didnt work lol.
 
Good News! Did a double batch this weekend, and the new cals worked very well. I was off +/- 3 degrees on my mash, it would go over by 2-3 and then under by 2-3 so it was much better than the previous cals that would overshoot by about 10-15 degrees. Next step is to replace my small diameter coil in my HLT with a 1/2 coil.

I'll be replacing that and brewing again on Sunday, and I'll give another update on here with how much of an impact the smaller diameter coil had on my system.

Cheers
 
Did you auto tune after you adjusted p, i, and d? What values did you end up entering?
 
I've made changes to my setup and I've tested a few batches on it since. I get spot on temperatures within 1 degree for the whole mash. I also use it to recirculate after boil and i get to pitch temp in about 15 minutes. I love the larger diameter coil, i went with a 1/2" ID copper coil.

Just moving which temperature was being monitored from the outlet of the MLT to the HLT made all the difference.

Cheers. :mug:

 
Last edited by a moderator:
Just so I understand correctly, because my setup is similar to yours:

You are recirculating the HLT water and your PID is measuring the temp at the point where this exits?
And you are just manually measuring the output to the HERMS coil to make sure it is the same as the HLT?

On a side note, I also have a little tan pump but have not used it yet to recirculate the HLT, do you just open the ball valve all the way when you are recirculating?
 
cank said:
You are recirculating the HLT water and your PID is measuring the temp at the point where this exits?
And you are just manually measuring the output to the HERMS coil to make sure it is the same as the HLT?

On a side note, I also have a little tan pump but have not used it yet to recirculate the HLT, do you just open the ball valve all the way when you are recirculating?
Click to expand...

Yes and yes.

My whole process is to add the water I need for the mash to the MLT and fill my HLT (5 gallons) and I will recirculate through the HLT until the MLT and HLT read my mash in temperature (for me 10 deg above my target temperature). After mash in this usually puts me 2-3 degrees below my target which is enough to bring down the HLT water to my target mash temp and my MLT water to my target.

For my system, my HLT water needs to be 3 degrees above what my desired mash temperature is for the water returning to my MLT to be at desired mash temperature.

I researched the other "Big" HERMS setups on HBT for a few weeks before I came up with my system. There are those who measure the output of their mash, the output of the HLT, and the temperature after the heat exchanger. I've found that my setup works best for me, and I would recommend it to others as well. I will say, however, that it depends on what hardware you are using to determine exactly what the best approach for you.

Side Note. I open my HLT recirc pump all the way.
 
I understand why your first attempt (pid probe at the mash tun output) didn't work and that the current way should be much better, but have you tried it with the pid probe at the herms coil output?
 
kevink said:
I understand why your first attempt (pid probe at the mash tun output) didn't work and that the current way should be much better, but have you tried it with the pid probe at the herms coil output?
Click to expand...

I did think of that as well, but since I'm using a cooler for a MLT, i lose heat very slowly. I havent tried it, but I would bet if it was there I would overshoot my temperatures.

Being as it works perfectly for my setup now, I probably wont try moving it and risk another batch having rampant temperatures.

That was, however, my second experiment if the first attempt didnt work.
 

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