Pid temperature control

[zamo27]

I'm about to start building my keg pot still to mainly to gin rum and occasional whiskey or vodka

I want to control my still with a pid temperature control but I'm not sure where should I stick my probe? Above the element? Top of the keg before the column or at top of the column before the bend?
Thank you

[Windy City]

Put the probe in your mash tun
Save that pid for your brewery you can't run your still by temperature. To make it simple you run the still by power input and product output. Check out the new distillers reading lounge lots of info in there that will help you on your journey

[zamo27]

My understanding about this is that methanol comes out first and evaporated at 68 then ethanol and I should start collecting at around 72-78
Can this not be monitored and controlled with a pid

If I control the elements input then the output is on target
Am I right?

[thatguy1313]

Nope. The different fractions don't separate perfectly like that. Otherwise everyone would make pure ethanol with a pot still in one run ...

[zamo27]

Of course but one can't just turn the 2800Watt element and hope for the best
There' must be a guideline temperature?!

[The KYChemist]

There is not a guideline temp. All stills are different, and will require a different amount of power input. You run a pot still by takeoff rate. Since all stills are different, each one will require a different amount of power to achieve the optimum takeoff rate. This is usually considered to be a broken, or twisted pencil lead sized stream. That is why nearly all electric stills have a power controller. Think about... The old timers didn't just build a bonfire under their still and get product. They had to adjust their fire to get the best takeoff rate. Thermometers are really only good for reflux stills, and even then, they are not necessarily required. This is all stuff that can be found out, here, through basic research.

[Windy City]

Of course but one can't just turn the 2800Watt element and hope for the best
There' must be a guideline temperature?!

No you don't want to just turn on the Element and hope for the best you need a controller so you can control the amount of power input which then controls the amount of product output. You cannot run by temperature in a pot still. Your boiling point will be set by the ABV of the wash/mash and will continue to increase as the ABV goes down.
I earlier recommended the new distillers reading lounge of which we consider mandatory reading. I really suggest you spend the time and read it a couple of times. All your questions and a lot of questions you didn't know you had will be answered there.
This is a great and rewarding hobby but only if you spend the time to learn.

Good Luck
Windy City

Edit posted same time as KY

[LWTCS]

Your boiling point will be somewhere between 173 and 212 depending on the amount of alcohol in your starting boiler charge.
As the alcohol is rendered out, the temps will naturally increase.
If you try to use a thermostatic controller you will never get all of the usable alcohol out of the boiler unless youu set the thing on 212.
But that will surely give you poor quality separation.

Try and picture requisite power input as a flame. High flame represents lots of input, and low flame represents minimal input. But no matter what the flame must remain in order to optimally drive the still.

[MitchyBourbon]

When running a pot still, you need to control how vigorous the boil is, not temperature. Think about what happens when you boil water on a stove. If you heat water to the point at which it just barely boils and take the temperature it will read 212°F. Now crank up the power so that you have a very vigorous boil. Take the temp again it will still read 212°F. Now, with a pot still you might want to do strip runs with a fairly vigorous boil but on a spirit run you want a mild boil. Your pid is not going to be able to do that. You need a controller that controls power output manually. Lastly, the boiling of a water ethanol mixture is not static, it slowly changes with the ratio of water to ethanol.

Edit: Posted same time as LWTCS, and apparently same thing.

[rad14701]

I think this horse has been beaten to death...

As mentioned multiple times, you need to do more research... You need to have a handle on the theories and fundamentals before proceeding... And forget those charts that tell the boiling points of ideal solutions... Miscible liquids defy those charts...

[thatguy1313]

Poor horse ...

[Bob Loblaw]

I think we need a rule about not discussing PID control of boiler temps...

[Windy City]

Poor horse ...

Now that's funny

Hey Bob I don't know what a rule would do to fix it we already say that new distillers reading lounge is mandatory reading but this question still pops up twice a week

[Hound Dog]

I think we need a rule about not discussing PID control of boiler temps...

I vote for that one. It constantly comes up. I guess its the day of automation. While controllers can play a part, i.e. Odin's IStill, it's way more than sticking a PID on a pot still. I would imaging much software is involved.

Is there a way to make someone pass a test before they can post?

That might be going too far....

[acfixer69]

I think we need a rule about not discussing PID control of boiler temps...

What is wrong with using a PID for controlling the input. The acronym PID in it self says it is what it does. The PID doesn't control a temperature or read a temperature only. It has many uses. Power input is one of them. Read up a bit and learn before you give advice like that.

AC

[underdog]

Read all that you can, pal.
Somewhere in your research, you'll read that folks running pot stills use their heat control to control the amount of product that comes out of their still. As the run proceeds, more power will be necessary to maintain the same amount of distillate flow.
More heat = more vapor = more distilled liquid.
The boiling point of what's left in your pot increases as the alcohol goes out the top.
If you're going to try to use a PID to control temperature, it'll end up cutting back your heat in response to the normal temperature increase during the run - exactly the opposite of what you need to do.
If you think about it for a few minutes, you'll see why it's not recommended.

[Hound Dog]

Come on AC, you've been here a while. You know you are stilling at boiling points of the mixture not just the boiling point of ethanol. I am sure you know the heat input just controls the output volume. What Underdog said is right. Yes it can be a little different for reflux stills but it is still much more than sticking in a PID.

That horse has been beaten to death, run over by two tractor trailers, eaten by buzzards and shit back out by now.

[bellybuster]

what AC is getting on about is the fact that PID's don't necessarily have to control temp. They are very efficient at controlling power as well.
In this case, a temp probe is not necessary at all. Use the PID as a power control only if it has the options to pull it off.

[HDNB]

there is other uses too, like safety shutdowns for example if the distillate temperature is higher than "x" cut the power...

i think the question was more addressed by the ded horse though... here is a great thread for everything that plugs in. Jimbo's conversion is well documented with links and i really liked: Cranky's super simple SSR controller, but you'll have to search it a bit it seems to have got lost in time line.

http://homedistiller.org/forum/viewforum.php?f=85

I think PID's just show up more in power controller searches...kinda like voltage controlled SSR's are everywhere but resistance controlled SSR's seem to be about 2% of the the offerings on the on-line stores. I know it took me forever to find the right ones on amazon and ebay. If you have never built one, this adds to the confusion.

[acfixer69]

what AC is getting on about is the fact that PID's don't necessarily have to control temp. They are very efficient at controlling power as well.
In this case, a temp probe is not necessary at all. Use the PID as a power control only if it has the options to pull it off.

+1 was pointing out that it is proportional by name and is what it is made to do, along with other functions as well.

AC

[Bob Loblaw]

AC -
Wasn't a rant about PID's in general. Just the concept of running a still via fine-grained control of boiler temps. I'm pretty familiar with PIDs, thanks.

[MitchyBourbon]

I think at least some of us that brew beer know what a PID is, I have one on my mash tun. The op said he wanted to use it for "temperature control" not power control.

[Hound Dog]

I think at least some of us that brew beer know what a PID is, I have one on my mash tun. The op said he wanted to use it for "temperature control" not power control.

+1. The OP's post is what is referred to as not working.