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First Bubbler Run ruined by burnt taste & smell

edited January 2019 in Usage


I’ve been making some great rum from my Pot Still for quite a while and had great expectations on my first bubbler run - unfortunately I’ve probably made a school boy error somewhere as my first batch of rum has a distinct burnt smell / taste. I’d be really grateful for some advice please. I’ve got a 100L Milk Can with 4 x 4inch ProCaps / director tees (Dash 2). I’m running with 2 ULD Camco 5.5kW elements. The lower element is on a controller.

Steps I took as follows:

  • My original vinegar run (about a week ago) took about 3L of white vinegar with enough water to cover the bottom element. I figured I didn’t need to run the top element as it would be immersed in vinegar steam during the process. Kept it on for 5 mins after it started steaming then rinsed through with cold water. I stripped the column and washed it. Perhaps I should have fired up the top element as well?
  • Made about 90L of rum wash (it was the maiden run on the temp controlled fermenter too). Fermentation finished easily in less than 5 days and I turned off the heater before bedtime. Temp dropped from 38°C to 21°C by morning. I then crash cooled from 21°C the next day to 2°C by mid-afternoon. I kept the wash at 2°C overnight before pumping out the wash into the Milk Can. There’s no filtering on the fermenter, but the "arm" bends up so that the pump will pump out all but the bottom 2 inches or so. I took another inch by gently tipping the fermenter and pouring it through a couple of sheets of kitchen paper to catch the yeast.
  • Other advice on the forum suggested running my 4 inch column at about 2.5kW to 3kW. I struggled with this. As it’s so cold in the UK (and I have a Super Dephlegmator) the slightest amount of cooling would put the column into full reflux. I felt that when running it with slightly less cooling almost switched the RC off i.e. running in pot still mode. I should add that the reason for this challenge is due to my element controller reporting slight variation of voltage through the run. I get the power wandering up and down by approx 80W without me touching the dial. This is enough to switch the RC on and off, so no good. I got around it by upping the power to approx 3.7kW and then I could run the RC with a decent amount of reflux through the run and it would not be influenced by a slight power fluctuation. I maintained take off to no greater than 2.5L per hour.

There are so many variables I’m unsure of the cause.

  1. If I should have done a vinegar run on the top element, it has now been used twice for 30 mins (I had to finish the run the following day). Is that enough heating time to burn off any “newness”?
  2. If it’s yeast burning on the elements, how do I avoid this? I think I was careful with the transfer of the rum wash, but I could look at buying a 1 micron inline filter and housing - not sure if my pump is man enough to handle it, but I can enquire with the supplier. Is 3.7kW too much power during normal operation?
  3. I don’t really know what is meant by “the plates flooding”, but I don’t think they did i.e. my top tee looks similar to all the videos that other forum members have posted, with the wash bouncing up and down on the plates. I did notice (before I upped power from 3kW to 3.7kW), there was a tendency for the top tee to fog up. This cleared and didn’t happen again when I used more power and therefore was able to make decent use of the RC. Is my Super Dephlegmator too efficient for winter use in the UK? Should I purchase a less efficient RC?

Thanks in advance.



  • Did you inspect the elements at the end of the run?
    If so, were they coated in burn-on? I suspect they were.

    Either your running too much power resulting in the scorching or you've carried over yeast and this is being burnt on.

    I've "burnt" rum before but that was caused during a pre-treatment process and the result of forgetting to add water before I boiled the molasses.

  • Could also be residual sugar if the fermemt was not as complete as you thought.

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

  • @Punkin - Definitely no residual sugar. The ferment went like a train, and I tasted it afterwards. Not a hint of sweetness

    @TheMechWarrior - I'll empty the milkcan tomorrow and check for burn-on. I'm sure you're right.

    So, presumably everyone filters through a cartridge filter on the way to the boiler? Are there any issues with the pump setup, as I imagine a 1 micron filter will slow the flow a bit and put the pump under a bit of strain?

  • Camco elements are anything but ULTRA LOW density. I did the maths on them the other day and it has a high value.

    Try insulating your boiler and column. Here you will find benefit.

  • edited January 2019

    Thanks @Richard, I will definitely do this. The ambient temp in the room is 11°C and this certainly requires more power to be used during the run than will otherwise be the case.

    What about filtering of yeast though? Does anyone do this? I'm considering an inline cartridge filter when I pump from FV to boiler. I believe I need 1 micron filtering because I've read yeast particles are 3 to 4 microns in size. I'm presuming this won't remove any flavour from the finished rum wash, but I don't know for sure

  • edited January 2019

    Hi - I have been speaking with (Mark) regarding my FV setup. He doesn't think that yeast per se is causing my burn issue. He told me brewers often go wrong with too much power and it burns the proteins in the beer wort. He thinks that 2 x 5.5kW elements is way too much for a 100L vessel to heat a pot of rum wash (due to the unfermentable sugars). I'm thinking my problem may be made worse as the milkcan doesn't have an agitator - I guess an agitator would help. I am going to try the following on my next run:

    • Crash cooling to 2°C for longer; probably 48 hours at this temperature
    • I will only use 1 x element until I can get another controller for the second element. Then I can heat 6kW when I'm only using 3kW on each element
    • I will have boiler insulation (thanks @richard) and not run faster than 2.5kW when up to temperature.

    Hopefully these adjustments will solve my issue. I'd appreciate any feedback as to whether I'm on the right track - especially without the yeast filtering.

  • Sounds logical to me, that's what i think the issue is, burnt sugars.

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

  • edited January 2019

    Flooding is when you get a significant mass flow of liquid going up the column. Plates then dont get separated anymore from plate to plate. That your plates begins to ”pump” a little bit is not flooding. Or even splash a little bit.

    1. Weeping: plates, trays, packning will not hold any significant amount of liquid. Vapour flow to low, to much Holes etc in plates. A bubble cap will normally not weep.
    2. Pumping
    3. Flooding (a significant mass transfer of liquid will move with the vapour)
    4. Full flooding (Almost all or all liquid will move with the steam) this is normally refered to something else when the column is shooting out the mash and can be triggered not only be the heat load bit also mash ( foam) hitting the column.
  • edited December 2018

    Thanks @punkin - I should have paid more attention to your first comment :-)

    Hi @Oswald - After viewing some YouTube videos of plates flooding, I've realised I definitely didn't do that. It was just a case of too much power for the wash, even though I didn't flood the plates

  • Some kind of auto editing took place in my last comment it was 1-5 and i left 2 blank as i dont know the ”name” of normal operation (without pumping, which is relative normal)

  • edited January 2019

    I've cleaned out the Still and put on another 90L of rum wash. Although I realise the cause of the burnt spirit was the power, I'm slightly surprised as there are lots of posts recommending the use of 5.5KW elements. I guess these might be ok for TPW runs but not rum where there are unfermentables? So, I'm planning to go no higher than 2.4kW for the run next time. Is there generally a rule of thumb on how much power I can use when heating the pot i.e. 90L? Using the SD calculators, I can see that 3kW will take broadly 2 hours - an awful long time ...

  • Are you using molasses?

    StillDragon North America - Your StillDragon® Distributor for North America

  • I used to get a tough, white, ceramic like chalk buildup on the elements, it was definitley not sugar but would burn and stink a batch and ruin it, I had a 2 stripping runs of 55%rye male and 45% barley malt that have a very phenolic smokey smell... before I noticed it..

    I switched to shiny stainless Dernord 4500W elements in my SD EGK's in my 380L SD boiler and they stay shiny in 95% of the runs. I also have some 5500W ones I run on 208V that work good too... Previously I was using camco elements and having bad buildup on runs that seemed to ferment all the way, but all solids are not sugars, but they will still scorch...

    I clean the stainless elements when needed in a bucket of PBW overnight, and then a light brush or green scrubbie...

    Oh, and the non-stainless-base Camco's... do not use them if you are doing lower pH runs like molasses, every one had the threads eaten down to the point where the pressure of the wires in the EGK was the only thing holding the element seal in... and anything stainless should be well passivated before using in a low pH wash run!

  • Thanks @CothermanDistilling - much appreciated.

    @Smaug - Yes 100% molasses (good quality so I don't need additional sugar)

  • edited January 2019

    Hi @JayTee,

    I’m also in the UK and use a similar setup from time to time. My boiler can take 110L of wash without puking so is a similar size to yours, there’s a pic of it in pot mode in this thread.

    I don’t think yeast burning is your issue. Leaving a wash at room temp for a couple of days the siphoning off is fine. It’s not your elements or power either, I use a Camco 5.5kW element and a 3kW element (8.5 total), I use them both to heat up and then shut off the 3kW element on a strip, I’d use them both if my 2 inch StillDragon condenser would keep up and Iv never had any burning.

    Where are you getting your molasses? Iv uses a lot of different molasses and I think Gold Label tastes the best and is a decent price, free shipping if you buy 6 I think:

    Gold Label Molasses Liquid for Horses 5L @

    Did you take a gravity reading before distilling? Even a dry tasting rum ferment can surprise you with a big SG number, @punkin is probably right with unfermentables burning on to your element, was there a black crust on your element after distilling? Did the whole run taste burnt? Did you strip at all? A 100% molasses wash run through 4 plates with no strip will be really quite heavy, is the flavour definitely from something burning or is it just a bad taste from your molasses? I had to throw a batch away once because of a flavour I didn’t like that came from the molasses I used.

    Power wise I use 4kW successfully for most spirit runs on the StillDragon 4 inch ProCap plates so you don’t have an issue there....

  • Is brew builder a decent, legit store? Their prices seem really quite good, I was eyeing up one of their massive mash tuns!!

  • edited January 2019

    Hmmm. I'm not sure. @richard's and @CothermanDistilling's comments about Camco elements ring true with me. There was some build up on the elements. Overnight with citric acid cleaned them up nicely. I'm happy the problem was not caused by yeast. I have now lagged my boiler in 32mm insulation so I won't be needing so much power :-) The fermentation aspects aren't an issue. My washes start at 20 BRIX, and ferment out really well in 3 days. I shall probably downgrade my elements in time, but for now, I've got another temperature controller in the post. I plan to use both elements during the run but pegged back to 1.25kW each. I've tried a variety of food grade molasses and they all taste pretty good. Haven't tried animal feed molasses, but I would imagine they would have less available (fermentable) sugar and therefore require sugar to be added to the fermentation

  • I was using feed grade, 22-25 brix, and 5 x 4500W foldback-ripple in 380L with success...

  • edited January 2019

    Just been searching in my calculation book from when I last checked the Camco 5.5kW element. The watt density lies between 13.3 to 14.6 W/cm2. This is not ULD by a long shot.

    In my heating elements that I am making up at the moment, they are 6kW and are of SS construction. At 100% power, I get 3.6 W/cm2. Now we are starting to talk ULD.

  • @richard - Wow! Does this mean you have a business which sells these elements ... :-)

  • edited January 2019

    That’s like 25 feet of 1/4” element - and there are still concerns about surface temperature - so it can still scorch.

    You can gain similar watt densities by running huge 480V elements at 120V or similar.

  • ULWD = 50W per square inch or 7.8W per square centimeter or lower - from Kal of The Electric Brewery fame

    Roughly 6.45 cm^2 in a square inch. math - (2.54cm/inch)^2

    Camco 5500W is about 60w/in^2(~9.3W/cm^2), and the 4500W is about 50W/in^2(~7.8W/cm^2) - from

  • Ulwd is a misnomer that should be banned

  • edited January 2019

    So, run number 2 was better but still not perfect:

    Ran 1 x 5.5kW element at 2.5kW to heat 90L (over 3 hours!)

    Continued to run this element for the entire run. Further reading has shown that I originally misunderstood the role of the RC - believing I needed to pull 85 -> 90% ABV for the whole run ... The hearts were pretty tasteless and I believe had a very faint whiff of burn (nightmare!). Certainly it lacked the "fruitiness" that I get from my Pot Stilling endeavours. As a whole I needed to add back late heads to impart any flavour. The bottom line is that if I compare my white dog (@ 65%) with Wray & Nephew (@ 63%) - presumably also a white dog(?), mine was nowhere near as smooth. It will probably oak out OK, but I'm disappointed that I haven't been able to create a tasty white dog.

    The reason I mention all this is because I'm suspicious if the muted (and very slightly smokey) flavour of the hearts still point to burning. I doubt I'll see much on the element, but could this have been caused by the lengthy run (from 07:30 to 10:30 for heating, then the run finished at 17:00)? I don't want to change my molasses because they make a truly fantastic drink on my Pot Still.

    So - do people think I'd benefit from replacing the 5.5kW Camcos with perhaps 3kW ASCIOOs? I don't need more than 6kW in the pot. I'm unsure if controlling the 5.5KW elements to around 2.5kW (on 50%, off 50% say), causes a higher surface temperature and therefore causing "toasting" (mild burning!) than if I was to control a 3kW element to the same power (on may be 80%, off 20%)? I've been thinking this through and I can't make up my mind if the Camco element will still be hotter in this scenario.

    I'm thinking my next step should be to run both Camcos pegged back to say 2kW each on heating?

    1. I think you should try running the RC with as little water as possible to keep the plates working
    2. agree with your next step, alternatives are to run 2 x 4500W Camcos on PWM, or 2 x 3000W on a switch, the one 5500 is still an issue it sounds like.

    3. Do you settle your molasses? I recently found via arroyo docs that adding .5% by weight of ammonium sulfate (white crystal kind) and about the same of citric(for a .5pH drop) during a hot first dilution of the molasses drops more and compacts faster, meaning less to scorch...

  • @CothermanDistilling - Thanks re: (1) and (2).

    On (3), I'm not sure I completely understand. I buy 25kg tubs of food grade molasses (it's really smooth with no lumps) and just pour it in to hot water in the fermenter etc. I'll be interested to read more about "settling" if you can point me to the document please. I've always been a bit confused by some people adding citric to drop the pH. I'm not sure if it's my water here, but I always need to make it more alkaline to fit into the pH 5.2 -> 5.5 starting range recommended by Lallemand for yeast. Since following that advice and making sure my yeast nutrition is correct, my washes ferment out violently in about 3 days. I may be completely on the wrong track regarding your advice. Please can you explain further re: "hot first dilution of the molasses drops more and compacts faster". Thanks

  • food grade likely does not need it... if you were using distiller's grade or feed grade, which is less than 10 cents a pound in the US, you need to... you can test by taking a cylinder and putting 20% by volume molasses and the rest boiling water, and mix well and let set...

    The initial pH drop is to keep other things from growing, you may not need it, but if you did, and you drop from 5.4 to 4.9 before pitching, the yeast will grow fast enough and stop things like lacto, which can cause a ferment to go into the 3.xx range where yeast dies before it is done doing it's job..

  • The blackstrap I picked up from the horse feed place certainly needed treatment.

  • edited January 2019

    The high-end molasses is expensive stuff.

    High end "supreme/near-high-test" - I pay $515 a drum (55gal) - $0.78 a pound (ash < 3.5%, 68-75% sugar)

    High end "bakers" - I pay $360 a drum (55 gal)- $0.54 a pound (ash < 5%, 63-74% sugar)

    High end "blackstrap" - I pay $269 a drum (55gal) - $0.41 a pound (ash < 15%, 45-60% sugar)

    Bit more than the $0.10 a pound for the feed grade stuff.

  • edited January 2019

    BTW, I believe Wray and Nephew is a blend of very cleanly distilled continuous column rum base and high-ester pot still blending rum. Even the pot still would have been distilled higher than 65%, the column rum basically on the bleeding edge of neutral.

    You'll not be able to replicate it in single distillation, even the fermentations would be different.

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