A Guide to the 3 Chamber Still

For those of you new to the distilling world, a 3-chamber still is a semi-continuously fed still that has a reputation for producing very robust, aromatic finished spirits. Most notably rye whiskey and rum. Evidently, this type of still became popular during the mid to late 1800s. The earliest iterations of this still were manufactured by incorporating wood into the design. Later, these still designs were no doubt strengthened and improved with the use of metals.

By comparison, double Retort systems (for example) also have a strong reputation for producing very heavy-bodied rums. The double retort operates with a larger primary kettle and two smaller ancillary kettles that derive their heat parasitically from the primary kettle. For heavy rum production, the primary is typically charged with a rum beer, retort #1 is charged with a low-wines mixture, and retort #2 is charged with a high-wines mixture. See the below diagram.

The combined makeup of kettle charges coupled with the amount of dwell time that each charge has been previously exposed to heat is what ultimately contributes to the heavier, more robust aromatic finished spirit. I’ll touch on that here in a bit.

I digress here to mention that Stephen Shellenberger of Boston Apothecary frequently talks about the hows and whys of the reactive environment inside the still that is responsible for many of the aromatic qualities found in your favorite spirits. Especially rum. I would absolutely head over to the Boston Apothecary website and read through everything that Mr. Shellenberger writes about. The content there is very insightful. 

The double retort system does however have a much different process flow compared to the 3 chamber still. The double retort system is a true batch still in that it is the primary kettle that gets recharged with fresh beer after each subsequent run. The primary kettle does not typically get its heat from direct steam injection. Unlike the 3 chamber still, the double retort system is not really known for having an integrated beer preheater. Certainly, it is possible to replicate the process flow of the 3 chamber still with a double retort. But in doing so some inefficiencies with respect to material handling and heat loss would quickly become evident. 

Elevating each retort would allow the operator to exploit gravity when the liquid transfer part of the operation becomes necessary. But then there would be the expense of building the structure to support each retort as well as potentially gobbling up a larger footprint. For any similarities between the two systems, there are equally the same differences.

It is a bit confusing to me the more I think about it. I wonder why it was the 3 chamber still that went all but extinct rather than the double retort still? The 3 chamber still is objectively better technology. The 3 chamber system is more sophisticated than the humble pot still but just not fast enough to keep up with the column stills. The 3 chamber seems to have gotten lost in that space between basic and the need for speed.

If you have not already run across the story about this system’s resurrection, Todd Leopold from Leopold Bros. deserves the credit for rediscovering this lost design. Taking inspiration from whiskey blogging luminaries such as Chuck Cowdry and David Wondrich, and by reading through various historical source materials, Mr. Leopold discovered that the largest distillery in the world (at the time) used a chamber still even though they also used the more productive column stills. Mr. Leopold speculates, “why would a company like Hiram Walker, which already had a column still and is the most efficient way to make whiskey, why would they use the chamber still?”. Mr. Leopold then asserts “and the answer is flavor”. Todd and his brother Scott put their money where their mouth was and put forth a commission to have the still designed as they understood it to be built. 

With the exception of a few brief characterizations, there really was no actual instruction manual for how to run one of these beasts. Stephen Shellenburger does post a brief start-up instructional taken from American Commercial Methods of Manufacturing Preserves, Pickles, Canned Foods, ETC, by Charles A Shinkle. But really there was no reliable training manual for this still. So, Todd was basically going to have to rely on his experience and also employ some on-the-job training to run this still.

There are several design illustrations of this type of still. Though not near as much documentation compared to more well-known designs.

Here are a few illustrations that most inspired the StillDragon version of this design concept for your viewing pleasure.

So why does this design produce a heavier more aromatic spirit? Well, it seems the secret sauce is dwell time. Or to put it in terms that nearly everyone can visualize, longer cook time. Very often I have used cooking as an analogy for getting my head around distilling profiles. I’m simply not smart enough to take the chemE road to understanding why the reaction occurs. Though I do seek out how to make the reaction occur. 

Let’s move back to the secret sauce, literally. For me, a very good analogy is the classic Italian Sunday gravy. So if you can imagine we are in the kitchen and we’ve now prepared and installed all of our favorite red sauce ingredients into our big sauce pot. 5 or 10 minutes into our simmer, the sauce starts to smell good. We can smell the aromas wafting throughout the kitchen. Within 20- or 30 minutes time, the aroma has intensified and smells even more delicious. But if we lightly simmer our Sunday gravy for several hours the entire house is consumed with the most amazing, delicious smell ever. This same progression of aromatic intensification occurs with other foods being cooked as well. Bread and cakes, Beef and chicken are all pretty good examples of how as foods run through the progression of being first applied to heat and allowed to continue cook to completion progressively smell better though-out the process.

Mr. Leopold mentions in several of his interviews that the beer being fed into the column still only has about 90 seconds worth of dwell time in heat before it finds its way out of the column as effluent. By comparison, Mr. Leopold exposes his beer volume to as much as 90 minutes under heat in the 3 chamber. 

I suspect the operating range of the 3 chamber still can be somewhat dependent on the individual user. But if we consider that slow heat-up times, 100% reflux mode on the short batch column, sour mashing, dunder recycling, and perhaps a few other methods used to promote esterification all have one thing in common, protracted exposure to heat.

I liken the above example to exactly what happens in the 3 chamber still. The goal here is to of course distill out the ethanol. But a by-product of the process is that it requires more dwell time to do so with the 3 chamber design concept. More cooking time very often means more lovely aromatics. This may have represented an inefficiency in the eyes of the old-time distilleries that shelved this still. I suspect at the time that distillery owners that used these old stills did not afford themselves the luxury of exploiting the inefficiencies of going slower than the column still and likely didn’t think highly enough of the finished product to influence what was ultimately the decision to shelve this still design once prohibition was in full swing?

Keep your eyes peeled for the StillDragon version of this design. We’ll be producing a recipe development-size version of this system to drag to next year’s trade show destinations. Please stop by our booth and have a look in person.