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Primary fermentation head space

mpizzurro

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Hey guys.  Does anyone know how much head space is too much in a primary fermenter ?  I can’t find this is any of my books or online.  I know 20 % is optimum and CO2 from fermentation purges the O2.  But I would like an acceptable number range.  Example, 20-40 %.  Preferably from a reputable source like Brad Smith or John Palmer. 
 
mpizzurro said:
I can't find this is any of my brewing books or on line.

Your answer is in the MBAA Practical Handbook, Volume 2, Page 92.

Your range of 20 to 40% would just about cover it.

All fermenter freeboard (the term of fermenter headspace) is going to depend on gravity, pitching rate, fermentation temperature and yeast strain. The design or type of fermenter you use will depend on your brewing process. That's probably something you already knew.

I ferment under pressure and need only 8% headspace.  The same gravity beer at atmosphere can fill 20% headspace and still yield 6% blowoff. So, the process change allows 10% more wort in the fermenter with no blowoff, for an increased yield of 16%.

High gravity ales are anything over 1.055, by brewing science standards, which is to say, nearly every craft and homebrew. A properly pitched and aerated ale, at just 4 F degrees above optimal fermentation temperature can create 50% more krausen. So, it's a sliding scale: higher gravity = more krausen.

On the other end of the scale, a properly pitched and fermented lager may only need 12 to 15% headspace at atmosphere and less than 5% under pressure.
 
Very helpful. Thank you.
I currently use John Palmers how to brew book and Designing Great beers as my go to books. Plus other good sources I trust online like articles from beer smith.  Just can't always find the answers to the questions I'm looking for. And I'm not always fond of forums, although they can be a good tool as well, like in this case. Just find they can also be "rabbit holes" if you let them.
I Just recently subscribed to Zymurgy and ordered Radical Brewing as well to further my knowledge.
Is the book you mentioned worth the money ?  I noticed there was a 3 volume series on Amazon.  It looks like a very technical book.  Is it easy to understand and follow ?

Plus, when you say you ferment under pressure, you mean you hook CO2 to your fermenter ? 
 
The book is more than you need for home brewing. It's to home brewing what a book on commercial farming is to a vegetable gardener. I happen to need that level of knowledge to do my job. I'm happy to share it, too.

Try not to fall into the trap that there's a scientific based answer to every brewing detail. Moreover, don't fret that there is one, precise way to make beer. The references you have are excellent. If you're truly thirsty for the nitty gritty science of it all, then seek it. As long as it's pleasurable, for you. There's a lot to learn and it isn't always consistent.

There is art to brewing that science can't explain.
 
I totally get what you're saying and can't agree with you more.  Thank you for the good advice.  I'm a self taught brewer and try to always keep that stuff in mind. " More than one way to skin a cat " type of thing. " Progress not perfection ".  It's like cooking food sometimes. Doesn't have to be exact.
Actually a set of books like that might behoove me. My two buddy's and I are in the process of taking it to the next level. Nano brewery with tap room.

Who do you work for if you don't mind me asking ?

 
Asking how much head space you need is like asking how long it takes to ferment a batch. It depends. The yeast is the master here. We work on its convenience, not the other way around. How long does it take to brew a batch? Until the yeast is done. How much head space do you need? Enough to contain the yeast.  I'm not trying to be snarky. When I was in cooking school and I asked the chef how long to cook something, his response was always the same: "Until it's done." At the time I didn't like the answer, but now I understand it.

How much head space you need depends on your setup, what styles you are brewing, and what temperatures you are brewing them at.
If all you brew are mundane ales and lagers at the low end of the yeast's temperature range, then you need less head space than if you are brewing wheat beers at temperatures that produce esters.

Then there is the question of if you plan to use a secondary or not. If not then you want the minimum head space, and if so then the more the merrier.

Personally I have a large glass carboy (never measured it but it's at least seven gallons, maybe eight) that I got from watching the newspaper classifieds, and it's got plenty of space. Since I always use a secondary, I don't care if there is a lot of head space. Never had a blowout in this setup.  I rack into five gallon carboys so that the head space is minimal, and the brew can hibernate there for a months. Sadly I have a couple ales that have been sitting there since my chest freezer died this past Spring. Haven't replaced the keg cooler yet. Priorities. But when I do, I have a couple stale ales to drink!

I don't think there is a definitive answer to your question. It's too subjective.
 
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