Bain Marie Mash Tun and Stripping Still

We plan to use a second brand to do the second distillation but are intending to use SD for mashing and stripping. Does anyone have experience with larger bain marie versions of the SD stills set up in Bain Marie? We are looking at both bain marie and steam heat but so far the cost of a steam boiler plus installation is pretty high.

Here is essentially the specs we are considering:

2000L Mash Tun - Bain Marie
2000L Stripping Still - Bain Marie
Heavy grain in fermenting and grain in stripping. High rye content.

Does anyone have experience with these larger bain marie versions?
If so, what do you use for the HEX? Glycol? Oil?
What can I expect in terms of heat up time for both?



  • Rusty Figgins is recommending mineral oil as a heating medium. He also recommends turning on the heat source the night before (set on low) so that when you come in to work in the morning your tank is preped and ready for very rapid heat up.

    StillDragon North America - Your StillDragon® Distributor for North America

  • Hi @SummitST, do you have a picture, drawing or sketch of a Mash Tun - Bain Marie? I have two boiler factories here that are scratching their heads trying to figure it out.
    Please send me an email if you do.

  • edited April 2014

    Lloyd I have a drawing of a smaller version that I drew up a few years ago.

    The intention was to use 1/2 an oil drum as the outer boiler. This would be disposable as it would burn through eventually when heated with gas - but oil drums are easy to get hold of.

    The inner boiler is all copper and bolted together. This was intended for cooking corn (or other sticky grains) that would then be fermented on the grain. When fermentation was complete just bolt on the lid and do a strip run.

    No need for trying to sparge the gloop, just mash or cook and then ferment everything. The rectangular extension was just to increase the volume of the pot.

    It would have to be outside because it would leak a lot of steam as it is bain marie style. If to be used inside I would use a glycol based fluid instead.

    You need to be able to stir or agitate these during warm up otherwise the contents will burn. Even with indirect heating - because the mash does not dissipate heat very well until it starts to circulate by convection.

    (Some of the big old distillery gear have rotating chains inside them to keep scraping the bottom of the pot to prevent the grain from sticking.)


    800 x 738 - 119K
  • It actually needs to be more like this steam tun but bain marie style.
    Not sure exactly why they can't figure it out but since I've never used one its kinda hard to coach them.


    steam mash tun.png
    469 x 365 - 50K
  • edited April 2014

    Jeez that is BIG Lloyd. To modify a steam jacket I suppose you increase the depth under the inner container to accommodate the immersion heaters, add a vent to the jacket, and fill the jacket with water instead of steam.

    You either vent the steam off, or condense it and return it back to a header tank connected to the jacket. You do need some sort of level control for the jacket and this is easy enough to arrange if you put a float valve in a header tank.


    800 x 494 - 56K
  • No - I don't have drawings. I'm essentially looking for a way to mash using an electric set up so that I can pair an electric mash tun with the SD bain marie. If anyone knows of any options, I am all ears.

  • Also - has anyone tried using a SD still as a mash tun? Is that a feasible solution?

  • Thanks @Myles. I'm using your ideas and hoping the factory can figure this out.

  • edited April 2014

    I doctored your doctored up drawing Myles and sent it to the engineer again.
    Hoping he gets the idea.
    Added an insulation jacket.


    718 x 465 - 52K
  • edited April 2014

    If you have a combo cooker and stripper, why not just ferment on grain and spare the expense of the expensive lauter rakes and false bottom? Keep it simple.

    In the arrangement above, you are going to need a side man way to be able to shovel out the grain. Otherwise you are going to need to add water to drain and cleaning is a pita. At that size you are going to need the false bottom to be sectional so it can be removed out of the man way as well.

    If your process requires lautering, you can probably just get by with using a plain ol' insulated tank and a commercial on-demand hot water heater than can make all the 180 degree water you need. You can get a commercial Noritz for something like $1,000 that can do this. Probably way cheaper than a bain marie mash tun.

    If your process requires cooking cereal grains (corn) - there is no flipping way you are going to be able to lauter it effectively. You'll break the rakes or clog up.

    The electric bain marie combo cooker/stripper is still the holy grail of the commercial micro distillery. Theoretically you could process large volumes of mash without a steam boiler and can also do spirit runs on a standard SD immersion heat still (why even require a bain maire spirit still?).

  • I'm told that by opening the door and using the motor the rakes push most of the spent grains out. The false bottom is sectional.
    It looks to be getting closer:


    BM MT1.png
    551 x 349 - 31K
  • This is really sexy.

    How many total element ports for 1000l? 8? 44kw?

    I've seen an alternative configuration that mounted the elements in a external reservoir and used a pump to circulate the fluid. Not sure if that makes the construction more cost effective, but an option. It also opens the door to using larger flanged heating elements (3 phase). Suppose you could always just cap off and use the inlet/outlet.

    What about mounting the agitator on a bridge instead of flush mount to the lid? I'd imagine that center lid strip would need to be mighty thick otherwise. Assuming that both sides of the lid hinged to flip up?

    I really like the more squat configuration, makes getting in to clean it a breeze. How far away are you from getting a price on something like this? We are extremely interested.

  • edited April 2014

    Two large lids that are both removable manways, so that they can be sealed vapour tight.

    EDIT: I mean with the motor mounted on a permanent central strip as suggested above.

    That way if you wanted to you could also have 1 spare manway with a vapour path connection on it and use this as a strip still also.

    You have a great big heated boiler there already - might as well use it for two different purposes.

    I am not actually suggesting that you ferment in it, because there are some other issues associated with fermenting on the grain.

    However you could mash in it, ferment in something else, and then reuse this boiler as the strip still.

  • edited April 2014

    Tank like this put into a real production environment won't have time to be used as a stripping still.

    If one needs this for mashing then that means this tun will be cooking every day all day imo.

    Truth is we can do an entire suite of equipment for the same price as our closest competitor's single still. You fellers that have been shopping around know this already.

    StillDragon North America - Your StillDragon® Distributor for North America

  • speaking of equipment... @smaug what is the process for getting a price on a couple 7BBL conical jacketed fermenters...

    seems like a lot of people are importing them, so getting one or two should not be too difficult..: I think all these are made in china... and have virtually the same specs...

    here is a forum post that has a familiar look to the picture

  • edited April 2014

    So 800 to 1000 liters? I have a price for a 2 layer 1000L We will need the boss to weigh in on the dimple jacket.

    StillDragon North America - Your StillDragon® Distributor for North America

  • We were actually planning to only mash once or twice a week. Thats why I was wondering if anyone ever used the bain marie SD still for mashing as well. I guess I don't see why it wouldn't work. The heated jacket would keep it pretty warm but if you use an external heat exchanger you could do it, right? We'd prefer a seperate electric mash tun but we havent found a great price yet.

  • If you use a glycol thermal transfer fluid you can easily maintain 120 deg C in the bath. Use a commercial stabilised fluid with the pH buffers etc and 130 deg C + is possible.

    My glycol still is MUCH smaller and I will aim for 115 deg C as that is adequate for my purposes. I am using a pure non stabilised food grade propylene glycol. It starts to degrade at 121 deg C.

    Glycol is a massive thermal heat store. If your container is insulated it maintains its set temperature for hours with minimal power (or none) applied.

  • I think the down side is removing the grain from a BM still, I was going to use a steam jacketed one to ferment sugar cane but think getting spent grain out is not worth it unless you add water and take it out as a slurry... which introduces it's own problems... I am going to start by buying wort from the brewery across the street, bring it over in a square plastic tote on a trailer, transfer to plastic conical fermenter until I can get a deal on a stainless one... hoping @Lloyd and @smaug can source one of the ones above and not have to re-design it...

  • another link for sourcing fermenters without reinventing the wheel (I don't know how things work in that big country over there, but have to believe someone near @Lloyd already makes some of these to brewery specs)

  • edited May 2014

    @Smaug said: Rusty Figgins is recommending mineral oil as a heating medium.

    What kind/source of mineral oil? Food grade? What viscosity? How about peanut oil?

    Anyone try mixing water and oil? Enough water to cover the elements and then enough oil to fill? I'm a little concerned about localized temps around the elements reaching the smoke point of the oil.

  • We use mineral oil baths to calibrate any temperature instrument above 100degC. ATM I have Castrol in it running at 175degC for calibrating High Temperature Hot Water sensors, no problem unless you drop a match in it but really no different than cooking chips on the stove. I leave it on all day. If you put water in the oil, the water will just boil away and leave the oil.

  • My thought was that if the jacket was sealed that the minimal amount of water wouldn't be enough to increase the pressure above 15psi. By the time it had "boiled" the general temperature of the oil would be enough where the natural convection would be enough to keep even localized oil from reaching the smoke point.

  • edited May 2014

    Even at 175degC Castrol does not smoke, I will crank it up on Monday and see what the smoke point is, just out of curiosity. It does smell like a warm engine though but no smoke. 15psig = 1 ATM. You now have a heated pressure vessel and needs to be certified every year just like a boiler. It needs to be welded by a qualified boiler maker and certified prior to sale/use. What temperature are you talking about running the jacket at?

  • edited May 2014

    Not sure I follow the water+oil - I suspect that if you did try to float the oil on the water, you'd find a pretty significant thermal gradient at the interface, and I suspect you would boil the water before getting the oil up to temperature.

    You mention PSI - I wouldn't try to do this in a sealed jacket - this would be disaster. I don't even know if I'd want to do this with an open system - I could imagine hot oil spraying out of your filler port.

    Why not just run food grade mineral oil? The more refined the better (and more expensive).

    If you are concerned about reaching smoke points because of localized contact, run your heating elements at lower power, or use a heat transfer fluid capable of higher temps. Another option is to use a ramp controller on the elements - this would let you heat the transfer fluid gradually, or if you want to do this manually - just don't run the elements at 100%. You are trading off heating time for longevity. Another interesting option to consider is to use high temp pumps to keep the transfer fluid moving during heat up.

    To some extent all transfer fluids will degrade and will require replacement over time, should be looked at as a consumable, and you should concern yourself with disposal of the transfer fluid up-front.

  • edited May 2014

    A good quality highly refined mineral oil specifically for heat transfer would probably run around $1,500-2,000 a drum depending on where you are, what brands are available, etc. Maybe less if you are close enough to a supplier to pick up yourself. I was able to find a local supplier who carried Paratherm NF for somewhere around $1,300, so you might be lucky and save a few bucks.

  • I've tried soybean oil (smoke point: 425F) and peanut oil (smoke point: 450F) both of which have a smoke point similar to mineral oil with an immersed element in a 2" tube. Wisps of a visible "vapor" (seemed like smoke) came from both within a 10 seconds or so. I think a full jacket would behave better, but I don't know how much. The general temperature of the liquid was around 350F.

  • edited May 2014

    350F is a bit on the hot side, at those temps I suspect you'd get localized burning on the inside of the kettle/boiler with a thick mash. Heck that's near the boiling point of even 100% Propylene Glycol. Your temp at the surface of the elements was probably a good 100F higher.

    Steam at 5-10-15psi is approximately 230-240-250F - however the heat transfer is significantly better than with a liquid.

    I suspect cooking oils are significantly less refined that mineral oils. I can usually pick out the oil by taste, which means it's got enough impurities to impart flavor.

  • edited May 2014

    I have run 100% Propylene Glycol at 270F before now but wouldn't do it again. If i were to use it again I would try to keep it below 240F. With any thermal transfer fluid you have 2 problems to factor in:

    1. Try to heat it too fast and the energy can't dissipate into the fluid, and you get localised burning of the transfer fluid.
    2. If the fluid is too hot then the contents of the inner boiler will burn anyway.Run your steam jacketed still at 50 psi and I suspect your contents will burn.

    Smoke point isn't the only problem with oils - they start giving off irritant vapours well below the smoke point. Propylene glycol is not too bad which is why it is useable in the bain marie style double boilers.

  • OK, got the guys back home to crank up the oil bath, it started to just break smoke at 345degC. Also one of the guys told me that some of the oil baths they have come across in both the food and pharmaceutical industry have used engine oil as the heating bath. I guess they figure that if its contaminated with oil no matter what the oil is the batch is thrown away anyway.

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