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-   -   I need a Herms Expert (http://www.homebrewtalk.com/f170/i-need-herms-expert-420802/)

Schlomo 07-10-2013 07:25 PM

I need a Herms Expert
 
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.

ellijo89 07-10-2013 09:22 PM

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?

BadNewsBrewery 07-11-2013 11:55 AM

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.

Schlomo 07-11-2013 09:36 PM

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.

Yooper 07-11-2013 09:42 PM

Quote:

Originally Posted by Schlomo (Post 5341313)
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.

You also need to recirculate or stir the HLT water. That makes a HUGE difference!

ellijo89 07-11-2013 11:31 PM

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.

Schlomo 07-12-2013 12:22 AM

Quote:

Originally Posted by Yooper (Post 5341327)
You also need to recirculate or stir the HLT water. That makes a HUGE difference!

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.

audger 07-26-2013 07:53 PM

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.

Schlomo 10-01-2013 11:30 PM

Quote:

Originally Posted by audger (Post 5377454)
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.



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

Makes sense why it didnt work lol.

sasky7777 10-02-2013 07:17 PM

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