Typically, I brew in 6 gallon batches, and this often end up being more beer than I can drink. Well…than I can drink and stay married, employed, and not obese, I’d like to start brewing smaller batches. Recommendations on batch size or any other aspect of scaling down?
I brew 3 gallon batches and keg in 2.5 gallon kegs for basically the reason you mention. I like that I can brew more often this way. The smaller volumes also need less yeast (mainly a consideration for lagers), are easy to heat to boil, and easy to chill. The only problem is sometimes you get a good batch and you float the keg faster than you would like.
I’ve been brewing a lot of 5L batches that I usually bottle condition, but sometimes I keg. They are fast and fun. And a 5L batch fits perfectly in a “Little Mouth Bubbler” from Northern Brewer. I use one with a siphonless valve and bottle straight from the fermenter. I’ll post pictures of my small batch set up for you this afternoon.
I started by doing 4L batches but that is just too small. With 5L I can get about 10 - 12 oz bottles, dependably. And, as I mentioned, it is a perfect fit for the LMB.
I also use my 5L set up to grow yeast for 6G batches, which is a huge bonus.
Since I work in a brewery and have way more beer than I ever need and since I don’t really drink much booze during the week anyway 5L batches keeps me in beer at home and gives me a lot of creativity options. Hell, I do decoction mashes in my microwave! lol
Here’s the Fermenter I use
That can’t comply with the Reinheitsgebot! [emoji23]
Ha! Come on Professor, you know that’s not true! ;D
I’ll say that with the smaller thermal mass it’s more difficult to maintain mash temps for a full hour. So I do the decoctions out of necessity more than anything. Don’t tell Denny, but I notice a difference. 
You think you notice a difference, at least. And that’s fine.
At the very least there is a color difference and mash efficiency increase.
indeed
[emoji23][emoji23][emoji23]
I’ve got down to 1-2 gallon batches for about 6 years, and love it. In addition to all the normal advantages like fewer bottles on bottling day, shorter brew day, ability to brew on the kitchen stove with relative ease, BIAB, more variety in the cellar, etc… the beer also tends to stay fresher. I enjoy brewing, so if I want more, I just brew more.
I ferment in 3-gallon carboys or 1-gallon pickle jars. 
The things I have learned form doing small batches is that metric works way better than American/standard/whatever. You need to measure in grams, not pounds or ounces. And a refractometer is pretty essential since at this size a few ounces is a lot of beer.
I dough in at 2.6 ml per gram of grain. And it is important to measure your hops in grams since a very small amount increase/decrease can have profound affects on the final beer.
I also use a fine mesh grain bag since it seems like it takes forever to vorlauf to get the wort clear without. The mesh grain bag works great. I use a 2 gallon beverage cooler with a braided tube screen and then continuous sparge. I get about 80% mash efficiency.
This is my process as well. 3 gallons into the fermenter, 2.5 gallons into the keg. Super easy, and the total tonnage of things that I don’t have to concern myself with that I see others agonize over has convinced me that I will NEVER scale up.
I do 4 L batches in 2-gal food-grade buckets.
Go metric, buy a scale, and do everything by mass. At room temperature, 1 L water = 1 kg (within ~3 g at least).
At that size, even a cheap induction cooker can hold a vigorous boil. If I were still brewing in the house, I’d do the mash-in-the-oven trick, I’ve relocated my brewing to the shed; so i have to do the best I can with reflectex insulation to hold the mash temp.
I use 2-gal food-grade buckets for primary, but you can also get 1-gal mason jars or repurpose the 1-gallon “carboys” that Publix sells their organic apple juice in. Smaller thermal mass makes it easier to keep fermentation temps down – there just isn’t enough mass there to get much above room temp.
I’ve not yet made the jump to all grain batches but I have noticed some differences in splitting a 5 gallon extract recipe down to 1 gallon.
In my imagination the ratios would be the same but maybe things get thrown off by reduced surface area for hop additions/ cooking when using a smaller kettle.
Would that hold true for all grain?
You definitely have to recharacterize your system – boil-off, mash efficiency, hop extraction will all change.
I haven’t tried a side-by-side 5- vs 1-gallon comparison of a recipe, but there are inevitably going to be a lot of confounded variables in this experiment. But at 4 or 5 liters per batch, you can afford to iterate a bit and figure things out. And even dumping 4 liters hurts a lot less than dumping 5-gallons.
I notice a difference, but I am certain that it is all in my mind.
I brew primarily 3.5-gallon batches and use 3-gallon kegs. That is about as small and as large as I want to go for stand brew length. I currently also have a larger setup in which I brew 5.75 gallons and keg 5 gallons, but that is in the process of being sold off.
Thanks, all - great feedback. Ordered a 2 gallon fermenter.
I too, have two systems, but I’m keeping both. I have a 3 gallon that feeds 2.5 gal kegs, and a 10 gallon system that feeds 5 gal kegs.
The main criteria that dictate my brewing activity are time, or lack thereof, and weather, i.e. it gets really cold here in the winter.
During the winter, I have lots of time to brew, so I brew in the kitchen with the 3 gal where it’s warm and cozy.
During the other months of the year I have very little time to brew because of my work, so I brew on the big system to produce 5 or 10 gallons of kegged beer because I know it may be quite a while before I can brew again.
I have to say that I love brewing on the 3 gal rig. It’s just so easy, and simple, like it used to be before this hobby got so hopelessly out of control. 
I started with one gallon batches for that very reason.
Cheaper and less heart breaking to dump one gallon than five if it doesn’t turn out as hoped.
Takes up less space (sorta’) and I can get more practice brewing smaller batches more often.
Still curious as to why 5 gallons seems to be the standard size for recipes and equipment. Clearly a conspiracy is afoot with carboy manufacturers…