I did my last batch of extract lately and aiming to make all grain from now on. Since my biggest stainless cauldron has 12 or 13 liters capacity, I realised that my 5 gallon carboy wasn't fit for my situation, so I bought a 3 gallon on Kijiji. You may already see my problem here ;) The preboil volume must be higher than that. I red somewhere that it would be something like 4 gallons for a 3 gallons batch (Theres a more precise way to evaluate this)

My question is : Is there a "workaround" for my situation or I'm just doomed and have to buy a 100-200$ 5 gallons pot? Can I just add water afterward ? I guess not.. Any magical tricks? lol


EDIT : This post is also a good ressource for this topic


2 Answers 2


Have you been using your 5 gallon carboy for the extract batches? Partial (concentrated) boil and split boil are popular techniques for filling a fermenter that's larger than your kettle. Whatever method you may have been using to fill that 5 gallon carboy from smaller boil kettles could continue to work for your all-grain batches.

Your 13L kettle should be big enough to do a partial boil for the 3 gallon carboy. 10L is both a comfortable amount to boil in a 13L kettle and to ferment in a 3 gallon carboy with a reasonable amount of headspace. The boiled wort would only need to be diluted with enough water to restore what was lost to boiloff. You can even shortcut the dilution calculation which would normally be required. Set your pre-boil gravity to your desired Original Gravity, because they'll be the same after you've restored the water that boiled off.

If you want to target the 5 gallon fermenter with just one 13L kettle, I would recommend a partial mash technique. This is similar to what Roman was describing where you boil a small amount of high-gravity wort and then add sterilized water in the carboy. With partial mash, you can target a lower gravity from your mash and then bring it up to your intended boil gravity by adding a small amount of extract.

In a split boil, you'll have equal amounts of wort in two kettles. When it comes time to add hops or other boil additions, just put half in each kettle. A pair of 13L kettles would be just barely big enough to comfortably boil enough wort to fill your 5 gallon carboy, assuming you mean that the total volume of the carboy is 5 gallons and you're putting about 4.5 gallons (17L) of wort in it to leave some head space. If you don't have another 13L pot but you do have one that's at least 7L or so, you could do a split boil for that 3 gallon carboy. 5-6L in each pot pre-boil should boil down to a good amount of wort for that carboy.

If you want to do a split boil from all-grain, make sure that you run off your wort from the mash into a single larger vessel before splitting it or switch the run off back and forth between the two boil kettles so that they have a similar gravity.

All that said, if you're planning on targeting the 3 gallon carboy you should be able to find a no-frills 20qt or 24qt stainless steel stock pot for under $100 CAD. Then you can just do a full boil and not hassle with any of that extra work I described.

  • 1
    Split boil -- yes! I think his best bet is to do a full-volume boil, divided between the two pots he already has.
    – Jeff Roe
    Commented Aug 7, 2017 at 18:45
  • Thanks so much. I think I'll try your split technique first then look for a bigger kettle afterward.
    – JFC
    Commented Aug 7, 2017 at 19:41
  • @Wyrmwood It's true that the common partial boil setup with a 3 gallon boil targeting 5-5.5 gallons in the fermenter is basically impossible with all-grain, but it is viable for the setup Carmer describes. I've added more detail about the "partial boil" scenario I was envisioning for the 13L kettle and 3 gallon fermenter.
    – Simon
    Commented Aug 23, 2017 at 21:23

Yes you can add water directly to the fermenter, but that water has to be sterilized (always) and chilled (unless you're practicing no-chill). Theoretically, higher gravity boil would facilitate Mailard reactions etc, but as you've just started brewing it's the least of your worries.

Smaller pre-boil volume, however, means lower extraction efficiency, because that "extra water" ideally comes from sparging. So you need to adjust your recipes to that efficiency.

Probably, lower hop utilization rate will occur, but I don't think it will have any real impact.

Having said all that, it is still going to be rather uncomfortable using 13-liters kettle, if you intend to fill it to the brim (as you will likely have to). My personal preference is to have 1/4-1/3 of kettle free space above the boiling liquor.

  • I actually have no knowlegde about efficiency. So I guess i'll have to buy a new kettle :S. Thanks a lot
    – JFC
    Commented Aug 7, 2017 at 5:53
  • 2
    Good answer, except for the part about water always needing to be sterilized. I've added straight tap water to dozens of batches. Of course it depends on your water source, but I would think most people in the western world can use tap water directly.
    – Jeff Roe
    Commented Aug 7, 2017 at 17:18
  • 1
    I agree completely with the comment above. I think if water is safe to drink form the tap it is safe to brew with. Brewing beer is a useful way to render water fit to drink. Commented Aug 9, 2017 at 9:49

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