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PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 6:57 am
by ABV 95
Could any one please help me with the settings for a pid controller?

I want to use the controller for a RC cooler in a bubbler.
I tried a few settings but it wil not keep the temp constant.

I'am using a selonoid valve wich is controlled by the pid, but it overshoots by at least 1 degree C.

The controller is a rex-c100.

Kind regards

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 7:09 am
by Doubleuj
Sounds like you’re trying to automate your still :angry-banghead:
Hope this isn’t a plan to leave it unattended :law-policered:

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 7:30 am
by woodduck
Don't think it will work anyway. An rc can take anywhere from 1-5 minutes to settle after an adjustment. That valve would be on and off all the time and the rc would never settle properly. Going from full open to full closed just wouldn't work I wouldn't think.

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 4:31 pm
by ABV 95
Not planning tot leave it unattended but it would make a little bit easyer do something else in the shed ( :obscene-drinkingdrunk: )

I've seen the idea somewhere on this forum but i cannot find it anymore. It was a while back.

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 4:36 pm
by bluc
Are you trying to control cooling water temp or vapour temp. Reflux condenser Cooling water temp is the go with a electric water solenoid contrling flow. (DONT PUT THIS TYPE OF CONTROL ON A PC. ALL YOU WILL ACHIEVE IS ETHANOL VAPOUR OUT THE END OF PC.) Apparently on off ones work. I havnt done it but others have. Be prepared to spend time dialing in temps as the will vary from setup to setup.


As doubleuj said. Unattended is bad. :handgestures-thumbdown:

I can't see a prob with automation if your constantly monitoring it.

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 4:44 pm
by RC Al
If your getting to within a degree, your prob not going to get it much better unless you go to a variable pwm control valve (dose such a thing exist? not sure i want to know the cost of that one...)
A strategy to try is to use 2 water inputs, a base one that cover 80-90% of the flow and then the rest on "fine" control via the solenoid

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 5:02 pm
by ABV 95
I think i made a mistake, i put the sensor in the vapour path. like bluc said it should be in the water from the reflux cooler.

I will go and try it thanks

And its not my intention to leave it unattended.

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 5:14 pm
by RuddyCrazy
A pid should never be used for a RC as if fault does happen it can just go haywire :scared-eek: far better to use a needle valve for the water input to the RC then one can dial in the right product stream with a tweak on the handle. zac gave me one for my bubbler and man did that make a difference to using a ball valve.

Far better using a pid with an element to match the ideal boiler temp and only use a pid on that on a still.

Cheers Bryan

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 5:30 pm
by RC Al
Bryan1 wrote: Far better using a pid with an element to match the ideal boiler temp and only use a pid on that on a still.

AARRGGGHH!!!!! :angry-banghead: :angry-banghead:
no, No and NO
Naughty Bryan1 :violence-smack:
About every 5th newbie assumes that one - and we have to work hard to convince them that it dosent work that way :sad:

Re: PID controller for RC cooler

PostPosted: Sat Oct 06, 2018 8:58 pm
by bluc
Cant controll a still by temp only power input. You would have to put the pid into manual mode then it would make for an expensive voltage controller. Far better off with a scr and a potentionmeter. Way cheaper and does same thing.

Pid is much more at home mashing grain :handgestures-thumbupleft:

Re: PID controller for RC cooler

PostPosted: Wed Oct 10, 2018 9:04 pm
by ABV 95
Thanks for the reply's. i could use the pid to check the temp at the top of my colom, or is the temp not important?

Re: PID controller for RC cooler

PostPosted: Thu Oct 11, 2018 6:25 pm
by bluc
If you do exactly same wash same sg same fg same ingrediants then temp at best will give you an indication.

Re: PID controller for RC cooler

PostPosted: Thu Oct 11, 2018 7:02 pm
by db1979
Temp above RC can allow you to determine abv but only accurate during hearts and if corrected for pressure (pressure changes with temperature).

Re: PID controller for RC cooler

PostPosted: Thu Oct 11, 2018 7:47 pm
by bluc
db1979 wrote:Temp above RC can allow you to determine abv but only accurate during hearts and if corrected for pressure (pressure changes with temperature).

Aka eparrot :handgestures-thumbupleft:

Re: PID controller for RC cooler

PostPosted: Tue Oct 16, 2018 5:20 pm
by ABV 95
I have a parrot so abv readings is no problem.

But is it usefull to make better cuts? Like in example keeping it below 75 degrees C for the foreshots and around 78 for the heads and above 80 for the tails?

Re: PID controller for RC cooler

PostPosted: Tue Oct 16, 2018 6:52 pm
by woodduck
You might be over complicating things here mate. Forget temps, I don't have a temp gauge anywhere on my still, no need. If you start chasing temps your still will be all over the joint, just let it do what it's gotta. These things are way simpler than you might think. Keep it simple and you'll have less things to worry about. One gate valve is all you need to run a bubbler :handgestures-thumbupleft:

Re: PID controller for RC cooler

PostPosted: Tue Oct 16, 2018 9:00 pm
by db1979
woodduck wrote:You might be over complicating things here mate. Forget temps, I don't have a temp gauge anywhere on my still, no need. If you start chasing temps your still will be all over the joint, just let it do what it's gotta. These things are way simpler than you might think. Keep it simple and you'll have less things to worry about. One gate valve is all you need to run a bubbler :handgestures-thumbupleft:

:text-+1:
Don't even need a parrot.

Re: PID controller for RC cooler

PostPosted: Wed Oct 31, 2018 11:27 am
by tipsy
A bit late to the game.

ABV 95 wrote:I think i made a mistake, i put the sensor in the vapour path. like bluc said it should be in the water from the reflux cooler.


This is what I did and while probably not as good as in the water path it works for me.
The temp does overshoot occasionally, but it's usually at the start and sorts itself out, or I'm overpowering the condenser.

Anyway it's a fun way to run a still and it has taught me about how a still behaves under certain conditions.