RIMS and HERMS temperature sensor position

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Kev888
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Re: RIMS and HERMS temperature sensor position

Post by Kev888 » Thu Mar 29, 2018 3:23 pm

Recently I've rather backed away from RIMS (or HERMS) as a key part of my systems, but have previously implemented it in a number of them. Quite a range when I look back, including HLT-based HERMS, traditional RIMS, Kettle-RIMS and both downward and upward recirculation.

FWIW, my general take on it is (perhaps unhelpfully) that there is not really a generic formula for control; things are so heavily influenced by general system characteristics that the requirements of different systems can be very different, especially if seeking some kind of best fit. Also, optimising (what might be called) the physical aspects of the system to begin with can be rather more important than subtleties with the electronics and sensors.

But loosely there has been a general approach that has frequently worked for me: Determining if/when targets are reached is based on the mash temperature, since the temperature of the mash is my actual objective. However, in most cases I would also have a sensor close to the heating device to control that - rapidly in the case of powerful RIMS elements, or where slowing flow could cause overheating.

If things go well then the relationship between mash temperature and heated wort temperature can be predictable enough. But there can also be a big distinction, so I wouldn't be without both in some cases.
Kev

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Re: RIMS and HERMS temperature sensor position

Post by PeeBee » Thu Mar 29, 2018 4:11 pm

EINBREW wrote:
Thu Mar 29, 2018 9:24 am
PeeBee wrote:
Thu Mar 29, 2018 12:18 am
Apologies for the delay responding, but to avoid the damage done in the last thread your posts are hidden from me and vetted before I can respond to them. Keeps the others happy?
Eh,.... I no understand?
Humm... yeah, denial, that might work too. But, for the sake of other readers I'll try a bit of an analogy:

"Over there is a big barrel of gunpowder. Here's a fuse and some matches. Off you go."

Far better you don't bump into the guy with the matches!



Anyway. I know you DO NOT use location "A" (in the HLT) for the temperature sensor controlling HERMS and therefore the MT. How do you handle the conundrum I've arrived at having the temperature sensor somewhere else?

My current feeling is that for the times the mash isn't being recirculated, if you need to heat the HLT for anything else it can be done with rough-and-ready methods, or manually, not the PID controller used for HERMS.

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Re: RIMS and HERMS temperature sensor position

Post by PeeBee » Thu Mar 29, 2018 4:28 pm

Kev888 wrote:
Thu Mar 29, 2018 3:23 pm
Recently I've rather backed away from RIMS (or HERMS) as a key part of my systems, ...
Aye. But what I was trying to do was present the techniques stripped of most "enhancements" and "cludges". Something to start out with and develop one's own "enhancements" and "cludges". I"m not trying to present what I'm doing as the answer - that will result in some disappointments and some seriously screwed up heads. (As I think you know by now, my head is already seriously screwed up!)

And look at the date. Wheeee, it's me birthday!

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Re: RIMS and HERMS temperature sensor position

Post by PeeBee » Thu Mar 29, 2018 8:33 pm

EINBREW wrote:
Thu Mar 29, 2018 4:42 pm
... When do you want to heat the HLT independently, ...
Thanks.

It's not about what I want to do, I'm already doing. It's building a picture of what others want to do so I don't make more outrageous suggestions. I do use my HLT like a boiler; heating adhoc quantities of water for purposes other than making beer (the "kettle" isn't an option for this in my setup). If many others are doing this, suggesting having HERMS controlled by temperature probes in the mash circuit is going to be a non-starter.


(EDIT: Update 20 May 2018. EINBREW is no longer a subscriber on this forum and has removed all posts made since joining. This may result in a slightly disjointed flow to this discussion as it refers to comments made by EINBREW which are not available for viewing any longer.).
Last edited by PeeBee on Sun May 20, 2018 11:03 am, edited 1 time in total.

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Re: RIMS and HERMS temperature sensor position

Post by PeeBee » Fri Mar 30, 2018 11:10 am

Edited the original post again, expanding the logic of the different sensor locations and tagging on a (interim?) conclusion.

Don't know about anyone else, but this exercise has certainly helped me understand why people have such conflicting views for placing HERMS sensors. It has made me realise I don't want to switch my HERMS sensor location (it's at "A") when I have the option to resurrect my existing RIMS (I've a very kooky HERMS/RIMS hybrid setup).

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Re: RIMS and HERMS temperature sensor position

Post by PeeBee » Mon Apr 02, 2018 12:55 pm

Noticed an interesting little detail in some data logging "EINBREW" had on another post (the following is a clip):
Capture.JPG
Temperature against Time. HLT in black, MT brown. Sensor in recirculating mash. PID tuning probably interferes a bit, but the HLT seems to be responding exactly like the OP was predicting - the HLT over-heats to start with (by 4-5C in this case) then slides back to meet the mashtun coming up to set temperature. Thus compensating for any tendency for the mashtun temperature to converge slowly with the intended (set) temperature.

The OP has been updated recently to be a little more "neutral" in tone, although it might now show a slight preference to using "Location B" for the temperature probe in HERMS.

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Re: RIMS and HERMS temperature sensor position

Post by PeeBee » Mon Apr 02, 2018 1:41 pm

Here's an example of a commonly laid-out heat-exchanger process control mechanism:
heat-exch.jpg
Parallels with the usual HERMS setup are a bit sketchy, so it is best to treat such information from "process control" textbooks with a lot of caution.

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Re: RIMS and HERMS temperature sensor position

Post by PeeBee » Mon Apr 02, 2018 6:07 pm

EINBREW wrote:
Mon Apr 02, 2018 4:06 pm
... this HERMS system is indeed a text book control problem. ...
I was only pointing out that "text-book" process control diagrams can give the wrong impression. Proof: The snippet in my post seems to have given me the wrong impression? But I do have to accept I might be below average on the intellect front: Impacting my head with a large object might have done that? (Large Object = Planet Earth). That might be responsible for me looking at your diagram and seeing steam driven ... RIMS? Hey, that might be an idea - RIMS that can't be responsible for scorching the mash as some fear the usual method does. Then again, all that high temperature steam, I find making a cup of tea a bit hazardous. Silly idea ... err ... but ... Who knows were I can get a valve that will handle steam and can be controlled by a PID? :)

But seriously. I hope you didn't mind me nicking a bit of your published data-logging (12:55 post in this thread). It nicely backs up the original post of this thread (not really "original", it's received a few updates) describing a possible and very beneficial feedback loop using location "B" (not "A"! You have made it quite clear you don't like "A").

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