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Pot Still Condenser Sizing?

Hi all,

A newbie here with first post, and probably a rather primitive question about a fundamental component issue. Am about halfway through my first 'build'.

I sure could use some suggestions or advice on how to size my planned Leibig condenser. Your thoughts would certainly be appreciated.

STILL stats:

  1. 15.5 Gal SS beer keg, with insulation for improved 'up to heat' times
  2. 2" (now) or 3"( later, but preferable) plain pot still copper column about 6"-12" tall with copper reducer transition to a very short (6") horizontal 3/4" run to the condenser connection.
  3. 5500 watt ULWD HWH element mounted in a 2" Tri-clamp fitting, assuming it will fit through the SD Element Guard Kit and with the DIY Controller Kit.
  4. Will be using Bakers yeast or distillers yeast (max 10-12%), but NO high ABV yeasts such as "Turbos", etc.
  5. Mash: Nearly all corn with minimal added sugars, (and possibly 10-15% other grain mash).
  6. My main objective is to make some decent sipping high flavor Kentucky/Tennessee 'beverage'
  7. Aged at barrel entry proof of 120-140 proof
  8. Cut to 80 proof for bottling/sippin'.
  9. 6-10 runs per year, at most.
  10. Will also want to leave option open to experiment with an 'optional' reflux head, and/or 3-4 foot added section of copper mesh packed column in the future, however high ABV end-product is not my real goal, and I'm not much into neutral spirits.
  11. Might also try to make little rum...

Am looking a two options for the condenser:

  1. 1/2" (product) in a 3/4" (water jacket) with 1/2" inlet and outlet water connections x ?? length, all copper.
  2. 3/4" (product) in a 1-1/2" (water jacket) with 1/2" inlet and outlet water connections x ?? length, all copper.

Both sizes could be up to about 28-30" long jacket length, (33-35" overall) to fit in my set up.

The condenser would use water cooling with small re-circ pond pump from:

  1. A chilled water tub (with added frozen 1 gallon jugs, as needed)
  2. Would also like the option to just draw water from a swimming pool @ 75°-80°F, or colder and discharge back into pool.
  3. Or use a 5-7 foot tall recirc drip 'chiller' made out of scrap wood slats in a large (3' diameter) tub
  4. I don't have much of a feeling for GPM flow rates, but am sure there are equations to figure this out, for optimal heat transfer.

Am trying to avoid any sort of 'choke point' from the condenser, for a nice balanced run.

Would prefer the 1/2"x 3/4" condenser, and for it to be short as possible, but just don't have a feel as to if it will be adequate, and pose no future limitations.

Most of what I see being sold for similar set-ups are 1/2" x 3/4" about 20-30" long.

Also, if the 3/4" x 1-1/2" is more approriate for my set-up, is there any value to winding/soldering copper wire around the OD of the 3/4" product tube to help prevent laminar flow and promote better heat transfer?

Thanks very much for any ideas, which you can share with me.



  • When i used to build keg pot stills for people i'd make liebigs with 1" over 3/4" 900mm (3') long. They'd work up to 5-6l/hr with a little copper mesh strung out inside them.
    Winding wire round the pipe and soldering it on here and there will promote turbulence and improve efficiency.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • Copper in the downward path is not recommended anymore.. not too many on here installing or making a new copper product condenser..

    A stainless SD 2" long condenser is what, $135? can't beat that with a stick... well, you can beat it with 2 long condensers in a row!

    If you want to see one work, come over to the gulf coast and I will show you how well one works with FL temp water...

    Here is a writeup thread I did a while back before I went Pro..

  • The answer to your question is very simple. Size of product condenser is directly related to the amount of power you put into the boiler. Energy in needs to be matched to the energy taken out by your product condenser. This is dependent on coolant flow rates, the temperature of the coolant going in, and the thermal transfer coefficient of the condenser.

    Personally I would not recommend a Liebig for use over 3 kW UNLESS you can go for one of the coiled designs or can use high coolant flow rates. The likely length needed for 5.5 kW is going to be more than your 30" specified.

    You are better off using a multi vapour path condenser - a shotgun.

  • I would clarify the statement "Size of product condenser is directly related to the amount of power you put into the boiler" by adding: "during product takeoff"

  • edited January 2016

    You mean I have to throw my copper liebigs away? Who made that rule?
    My pot still liebig lis 1" over 3/4" by 4' long and handles all the power my Bayou Classic propane burner can throw at it during a stripping run on my 2" copper pot still. I push around a gallon per minute of 75F cooling water through it when stripping. No vapor gets out, but it does huff quite a bit. Sounds like The Little Engine That Could.

    I think you're a bit optimistic about your pool water temp. When I lived in Central Florida my pool temp was 90+ for four months of the year. It got down in the low 60s/ high 50s in Dec-Jan. It saw full sun in the summer and full shade in the winter due to the angle of the sun and the shadow of my house.

    Go Knights!

    I'm more like I am now than I was before.

  • Comes out of the tap at 87 round here in the summer.

    StillDragon North America - Your StillDragon® Distributor for North America

  • @Kapea said: You mean I have to throw my copper liebigs away? Who made that rule?

    don't get you panties in a wad... ;-) I did not say to throw away your old ones, just "not too many on here installing or making a new copper product condenser.."

    The issue is Ethyl Carbamate or 'urethane'
    Whisky Science @ Blogspot

  • Yeah I read about that. I filed it away with power transmission lines causing leukemia, immunizations causing autism, and margarine being better for you than butter.

    I'm more like I am now than I was before.

  • Aluminum causing Alzheimer's?

  • Hey both words start with Al! What more proof do you need?

    I'm more like I am now than I was before.

  • edited February 2016

    I thought we already filed "copper and distilling" into the myth folder, right after chemtrails, and all of that nonsense about dents in scottish whiskey stills critical to the character of the spirit.

    I second the "stainless down" approach, but fully realize that in the hobby community, this pretty much means DIYing a condenser is impossible, so maybe not as realistic as in commercial.

  • If you have a copper one that works, that is great... but if you have not built it yet, just get a SD stainless long 2" condenser for $135... (or 2 if you have room), you can run just a trickle through them, and they work great with a danfoss valve.... now a dephleg, I like THAT in copper!

  • Yeah, $135 really is dirt cheap. If you had to go out and buy a small torch, a spool of solder, pipe and fittings, plus factoring in your time, the $135 is going to be the better deal. Plus, if you never sweated a pipe before, you have the added benefit of your rig not looking like absolute junk.

  • edited February 2016

    As @Myles points out, if you have copper in the up path, the compound in question (urethane) drops back into the column and/or boiler before it has a chance to contact copper in the down path.

    The first thing I built on my first still was my copper pot still liebig product condenser. My copper sweating skills were minimal back then. I planed my work carefully, cleaned and fluxed all the joins carefully, and was deliberate in my application of heat and solder. Once it was soldered together it was not ugly, just a bit rough looking. A hour's worth of work with a file and steel wool turned it into a thing of beauty.

    I can honestly say I enjoy the build as much, or more as the operation. It is very satisfying to have something built with your own hands work even better than you thought it would.
    (I built a lot of models and RC planes growing up)

    That said, my SD plated column and GB4 are my favorite pieces of equipment to run.
    Big boy Legos!

    I'm more like I am now than I was before.

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