Sub Pot in Boiler

I'm after some thoughts on this solution to a potential problem. I will preface this by saying I am new to distilling and still trying to get my head around the processes.

I'm trying to do a gin run with the gin head and when I did the first individual botanical runs I noticed that when doing the low charge runs I was getting very low abv. I'm assuming this is because of the high ratio of water to alcohol in the boiler. My proposed solution to this is to insert a deep pot in the neck of the boiler which takes the 45% abv spirit,then the boiler is filled with water submerging the sub pot. Essentially running it as a jacketed boiler where the boiling water then boils the spirit. Thus ensuring that you get a complete run through the gin head although you are only running a small amount. Oh and yes the milk can boiler is vented using the fill port a 45 , column and a vapor condenser to recycle the boiler water. I'll post pictures of the full set up tomorrow.

Cheers S


600 x 800 - 72K


  • Random new guy banging out some pretty trick looking stuff, out of nowhere.

    That clamp on double boiler - genius, looks incredible.

    Though I don't know that it has anything to do with your gin issue - what's the boiler charge abv?

  • I am deducting since he says single botanical, he may only have a liter or a few liters diluted with all the water needed to cover the elements... so it kinda makes sense...

  • Looks great and certainly thinking out of the box.. Only comment that I have is .... you now have a pressure cooker scenario IF this lip connects ontop of the boiler rim. This obviously can be quite a problem.

  • edited July 2016

    I think that's the point, he has a vent on the "jacket". By that little inner boiler having the lip, the existing clamp makes it air-tight from the jacket.

  • edited July 2016

    @si175 said: Oh and yes the milk can boiler is vented using the fill port a 45 , column and a vapor condenser to recycle the boiler water.


    Create your own steam jacket?

    • Fill water above heat element
    • Use the fill port with a 3 way T
    • Connect a pressure sender
    • Connect a PRV
    • Control heating element with a pressure controller

    Looks like a new product add-on to me for those who are looking to do thick mashes / grappa...

  • edited July 2016

    Yeah, this is good stuff. Compared to all the craptastic attempts at DIY bain marie/jackets, this just seems to be perfect.

    Granted, I'll go off the wall about safety in a minute or two, but from an ease-of-use perspective, fill, cleanup, all very easy. Could even be an upgrade for those with milk cans (although that lip and sizing needs to be standardized). Want to run a rye mash, just pop it in, fill it, and go. Want to do a spirit run off a strip, pull it out.

    I'd never thought to try to piggyback off that existing gasketed lip and clamp before, but it's the ticket.

  • Problem solving and fabrication is my trade so none of the building side poses to much of a problem, apart from to time side. Fortunately I'm between contracts at the moment. Re the abv charge this is the problem I've observed. Running a very simple packed column still with no reflux condenser, starting with a 14% sugar wash your potential charge in a 50 L run you have about 7 L of spirit and 43 L of water. When doing the run my product output starts at about 80% abv and then steadily reduces throughout the run. It actually a very consistent reduction of about 5% abv per every 800 mil taken. Thus if I start with a 1lt of 93% abv to 50lt of water I'm only starting with a 2% abv charge. This means my take off starts with a very low abv say at around 35% and trailing off. Doing this in pot still mode seems to amplify this issue in that there is near to no reflux to help in the separation of the product from the charge at very low abv in the boiler. ( I hope this is all making sense) In the test run with the GB4 when doing something like the oris root single run, because it's only around 1% of the finished product you'd only want to do a 50 ml run for a total finished product of 5 lt. What's going through the gin head is so low in alcohol that you are doing more of a water steam extraction rather than a alcohol extraction. I'd assume that this is not what you want. Hence my sub pot. Only what you put in goes through.

    There is a number of safety issues with this setup the main one is that you don't want to make a steam pressure vessel that going to explode on you, so yes it has to be vented, second is that every time you want to recharge it you have to dismantle the still, everything is very hot!! The other thing is that you can't see what's happening in the pot.

    Using the fill port in the boiler solves the still exploding part and I'm thinking of spinning a new lid for the milk can and adding in a fill port and a sight port to solve the second two problems.

    I'm about to do the setup for the still with the sub pot so pics will follow shortly

  • edited July 2016

    So here are some pics of the set up.
    I have it running and all seems good.




    600 x 800 - 75K
    600 x 800 - 73K
    600 x 800 - 78K
  • On the refilling: you could get a 4x2 reducer and use the sight glass port for refills

  • Well that was interesting. Did three test runs and got three different results. 1st run 500ml neutral 500ml water. Final product run resulted in 500ml of 80%abv with a soft nose to the botanicals. The gb4 shut down on its own at this point.It left most of the water behind. Second run without the sub pot. 500ml neutral to 25lt of water. Started at 30% abv and went down from there. Stopped after taking 1lt and the output was at 10%. Super hazy with an over bearing citrus nose. Final run with pot again. 500ml neutral and 1500ml of water. Final product came out with 550ml at 65% abv. This one had a more balanced and stronger nose. I guess there is a sweet spot with the pot charge. Probably at around 20% abv charge to the pot. Each run was done with the same volume and mix of botanicals I'll try again tomorrow.

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