# Kettle Volume For Specific Batch Sizes



## geoff_tewierik (14/12/07)

Hi all,

I'm looking for a table or equivalent which gives reference to the size batches that can be done in specific kettle volumes.

i.e. 20-23L batch in a 40L kettle, double sized batch 40-46L in 70L kettle. Or working the other way, what can be made in a 50L kettle, or a 20L stock pot.

And whether there'd be a different requirement for BIAB vs AG.

If something like this exists, please point me in the right direction, as simple searches here on AHB only give vague references to Joe Blogs using such and such kettle for a double brew, not an actual table of data. And if one doesn't exist I'm more then happy to colate others data from experience with brewing and produce a table of reference for others.

Cheers,

GT


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## newguy (14/12/07)

I don't have a table, but I can tell you that a 32 litre pot was enough to do 21l batches when I used to boil on an electric stove. I now do double batches (about 42l) in a 64l pot on a propane burner outdoors.

I can tell you what my evaporation rate was/is: 3.3l/hour indoors on the electric stove and 5.8l/hour outdoors on the propane burner. Work backwards from your finished volume of wort and length of boil and add maybe 3-5 litres for headspace to avoid boilovers, and you'll have your kettle volume.


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## sluggerdog (14/12/07)

I do 40 litres batches and I can do this in a 50 litre pot.

The trick is to work out a 10 litre top up at the end (via beersmith) and be careful with the initial boil as it is about 45 litres in after sparging.

Careful watching, Water Spray bottle and skimming gets me though everytime. I've done 25 + brews this way, 1 boil over only.


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## Stuster (14/12/07)

I've never seen a table like that, geoff, so it might be up to you.  The one complicating factor I see is kettle geometry, with more chance of a boil over in a tall, narrow pot than there is in a wider kettle.

Anyway, to start you off, my kettle is 50L and the largest batch I can do is 38L which is really pushing it. For sanity, I'd say a maximum of 30L would be fine. In fact, now I start to think about it, how does 3/5 of the total volume sound to everyone as a rough estimate for most kettle shapes and sizes?


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## Mercs Own (14/12/07)

I have a 50 litre boiling kettle and usually do a 44 litre boil (collect from sparging) which generally ends up after cooling loss and wastage etc at around 36 - 37 litres into the fermenter. Wouldnt want to do more in the kettle as boil over could be a problem plus after fermentation and racking etc I have enough beer for two kegs!

Hope that helps.


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## devo (14/12/07)

just watch out for the wheat beers. I recently did my first attempt of 23ltr batch in a 50ltr keg and the initial boil over froth took me completely by surprise. The thing was up and over the edge in a few seconds flat before I had a chance to back off the burner.


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## Tony M (14/12/07)

Newguy has nailed it. The evap rate needs to be known as it is a function of the heat input, so you will more or less lose the same amount to evaporation regardless of the batch size. Logically, the foaming will be more of a function of the wort volume though that seems to vary more with the recipe in use. You can work with very litle head space if you stay on guard with a stirrer and a spray bottle of water.


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## geoff_tewierik (14/12/07)

Taking note of the responses so far, and without adding any caveats to the table regarding boil overs i.e. go the next size or two up to cover yourself, I have produced this:


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## PJO (14/12/07)

geoff_tewierik said:


> Hi all,
> 
> I'm looking for a table or equivalent which gives reference to the size batches that can be done in specific kettle volumes.
> 
> GT



Rough rule of thumb for any batch size: 
20-40% bigger than your final volume after boiling is finished.
20% usable.
40% comfortable B) .

You could go less than 20% but you end up having to watch it like a hawk for boil overs.

So for 50L at flame out you will need a 62-70L kettle.

I've got an old 18gal (~82L) keg and my standard batch size is 50L but have done 60L batches with no probs.

I usually get around 10-11% evaporation per hour (about 8-9L for a 50L batch with 1.5hr boil)

With 50L I have about 4L loss in trub and hops at the bottom of the kettle, so 46L goes into fermenters and then I lose about 1-2L from each fermenter in yeast, racking and tasting, so end up with about 42-43L of beer. Enough for 2 cornies and a few bottles.

HTH,
Petr


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