Trouble holding temperature at 168 F

[SpaceGhost]

Hey folks. I'm doing my second run as I type this, my first was just about 3 weeks ago. I'm having some trouble with this wash however. I'm using a pot still and I'm trying to keep my vapor temperature to 168F to get rid of the nasties that come before the ethenol. The wash just doesn't want to work with me though. At first I thought it was my inability/lack of experience controlling the temperature, but I have set my burner to it's lowest possible setting, and the temperature drops like a stone, even with the wash temperature near 200F.

This is making me think I have very little acetone or methenol in my wash. I'm not overly experienced with "by taste" yet, so I was wondering if it's possible that my wash produced more ethenol then last time? Last time I used bakers yeast and did a wash with about 3%. This time I'm using Red Star DADY on a wash that is at 10%. It wasn't warm in the house so the wash hovered around 70F while fermenting so it took 3 weeks to ferment out. Is it possible that the new yeast and longer distillation time produced more ethenol and less of the early nasties?

[SpaceGhost]

I forgot to mention, I'm doing this first run like a striping run, so I'm going to be putting it all into my next batch. I know I don't have to be crazy about the vapor temp on a striping run, but I'm using it to try and get a handle on temperature control and cuts. This is also my first time with the copper packing in the tower.

[seamusm53]

Stop trying to control the vapor temp - -especially on a stripping run - just run it as fast as your cooling will allow. It is not only an almost impossible task to control vapor temp but more importantly you cannot use temps to make separation more efficient. Cuts with your spirit run are best made by taste and smell with or without airing out after.

[rubelstrudel]

The vapour temp is a consequence of the contents of the wash. It is not a parameter you can control.

[SpaceGhost]

I just turned up the heat to finish this run up a bit faster. I know a stripping run is quick and dirty, but I'm trying to practice my heat control. I figured all it is wasting is some time.

[rubelstrudel]

Turning up the power will produce more vapour, not hotter vapour.

[SpaceGhost]

Ok, I assumed if I kept the heat low enough that the methanol would boil off first since it's not an azeotrope with ethenol.

[rubelstrudel]

Common mistake. You'd think that was happening but it ain't. Research shows that methanol is more or less evenly produced throughout the run, regardless of production speed.

[OtisT]

Hi SpaceGhost. I believe you are thinking about pulling foreshots (acetone) and not methanol. For most hobbyists, methanol is not something to worry about. Some folks just let them smear in with heads but I like to pull foreshots slowly, concentrating most of the acetone into a small volume. This process helps me a lot with making cleaner neutrals.

As stated previously, you can’t control the vapor temp or output ABV in a pot still. The wash’s current ABV determines the current vapor temp and current output ABV. As you boil off alcohol over the course of a run a wash’s ABV gets lower. As wash ABV drops, vapor temp rises and output ABV drops. It’s all proportional.

Pulling foreshots

Like all operation on a pot still, Pulling foreshots requires power control. You can run your still with the charge temp just a hair below a full ethanol boil and foreshots will slowly boil off in less than an hour.

Here is the method. Bring the boiler up to first slow ethanol boil. Collect for a short while to heat up the pot head, then back power way down until collection output is 1 drop per second. Once you reach this drip rate, continue to collect at that rate for one hour. You can easily tell when foreshots collection is done, so you don’t have to collect for the full hour if they finish sooner. Once you are past foreshots, turn power back up to strip power or spirit run power levels.

I use between 200 to 300 watts to achieve a 1 drip/sec rate.

Otis

[NZChris]

I don't want to tack an extra hour onto each stripping run, so I like to collect my foreshot in about ten minutes then turn the heat up and get the job done. The spirit run sorts out the rest as long as you do your homework and choose your cut well. See Kiwistiller's guide to cuts.

The best thing you can do with your thermometer is tape over it or pull the battery out. It is causing you to make mistakes already. Anyone who tells you how to run your still using temperatures is just one of many uneducated newbies repeating nonsense they read on the web or made up themselves.

[Saltbush Bill]

A few things for you to ponder, regarding temps and how alcohols react in a still boiler
Firstly you can not regulate the temperature of the wash in your boiler, there for its kinda hard to regulate the vapor temperature.
Water boils at 100 C ......no matter how much heat you apply to it it wont get hotter...it will just boil harder and create more steam/ vapor.
Alcohols work in the same manner.
Acetone boils at 56C
Methanol at 64.7C
Ethanol at 78C
Water at 100c
That is only the boiling point of four of the many things found in the average wash.
Now to complicate things further you are trying to boil a mix of the above ...........what is the boiling point of that mixture????????
The answer is that the boiling point is constantly changing as the different / lower boiling point alcohols leave the boiler. It will increase the whole time as the ABV of the wash gets lower.
This is one of the things about distilling that many newbies have trouble understanding at first.
The last thing worth thinking about is that if you put a shallow bowl of water outside in hot weather , after a few days the bowl is empty. Liquids don't need to boil to evaporate and that is partly the reason you can never make perfect cuts / separate the fractions of a wash perfectly. Different still types do a better or worse job of it, pot stills smear worse than most.

[fizzix]

A few things for you to ponder, regarding temps and how alcohols react in a still boiler
Firstly you can not regulate the temperature of the wash in your boiler, there for its kinda hard to regulate the vapor temperature.
Water boils at 100 C ......no matter how much heat you apply to it it wont get hotter...it will just boil harder and create more steam/ vapor.
Alcohols work in the same manner.
Acetone boils at 56C
Methanol at 64.7C
Ethanol at 78C
Water at 100c
That is only the boiling point of four of the many things found in the average wash.
Now to complicate things further you are trying to boil a mix of the above ...........what is the boiling point of that mixture????????
The answer is that the boiling point is constantly changing as the different / lower boiling point alcohols leave the boiler. It will increase the whole time as the ABV of the wash gets lower.
This is one of the things about distilling that many newbies have trouble understanding at first.
The last thing worth thinking about is that if you put a shallow bowl of water outside in hot weather , after a few days the bowl is empty. Liquids don't need to boil to evaporate and that is partly the reason you can never make perfect cuts / separate the fractions of a wash perfectly. Different still types do a better or worse job of it, pot stills smear worse than most.

Absolutely brilliant, Bill.

[kpex72]

I don't want to tack an extra hour onto each stripping run, so I like to collect my foreshot in about ten minutes then turn the heat up and get the job done. The spirit run sorts out the rest as long as you do your homework and choose your cut well. See Kiwistiller's guide to cuts.

The best thing you can do with your thermometer is tape over it or pull the battery out. It is causing you to make mistakes already. Anyone who tells you how to run your still using temperatures is just one of many uneducated newbies repeating nonsense they read on the web or made up themselves.

Spaceghost,

As others mentioned you are not going to hold vapor temps in a Pot still - it will simply continue to rise. Bill's advice above is spot on. Read NZChris' post. He does what I do for stripping runs. However, I learned initially on a column still and now use a flute, and will pretend I didn't read his comment about thermometers and uneducated newbies . Keep the thermometer in there. You don't need a single one on a Pot Still, but I learned early on they can predict patterns. Use it to find correlations as predicators as to what is about to happen. They are great tools for awareness, but not for any decision making. After 22 years of fun in this hobby, I run 5 thermometer probes on my flute setup. Each proves valuable info, to me at least.

On my pot still, I like to remove the fores even in a striping run, as I feel you can never be too careful. There is a lot of controversy about this, but I still choose to do it. I run the pot still hard until the vapor head hits ~55c (Sorry I don't us F). That's when you get your first drip or two. I drop the power to the boiler about in half and collect the drips until they become a solid stream. This conveniently seems to consistently happen at 78C. This takes 5-10 mins depending on wash volume. Then crank it back up and do the strip run all the way out. What I initially collect smells just like acetone. Did I get it all - NOPE, but I got a lot. Then I use a column still to run the neutral spirit run and make proper cuts there. I'd make three modified stripping runs on the pot still to make enough low wines for a spirit run on the packed column.

Things a thermometer can be useful for: Finding the correlation at what vapor head temp hits 20%ABV, 25% ABV, or 30% ABV for your setup. One day you will break the alcohometer, or just not want to use the parrot. Once you see the temp correlations, use your sense of smell, taste, and feel of your output distillate to make your decisions. You would be surprised at how consistent the correlations are. When you step up to more complex setups, you will have a good understanding about reflux and vapor management using temperature. If you only plan on a using a Pot Still, the thermometer its still good to understand what is happening. You will also notice correlations between time and temps. This can help identify problems when the patterns get broken. Awareness is key.

Enjoy the hobby! (With or without a thermometer )