Can I just half a recipe?

[BrewingNoobing]

I'm looking to do my first brew that's not from a kit.

I have a pretty big pot, however It is smaller than 20L.

Can i take a recipe such as this one: https://www.tapsmagazine.com/a/, half the amount of grains and half the water used (Both sparge water and boiling water at the beginning)?

 

[IslandLizard]

Absolutely, go for it!

The only things you may need a little more of is water and/or grain, since boil off depends on your system, and mash efficiency on how finely the grain is milled and your mash/sparge process. You'll know when you come up a little short on volume and a little heavy on gravity at the end, or vice versa, or both.

Brew a batch at half and see where it puts you.

What is the volume of your kettle?

 

[Immocles]

I regularly split the recipes listed on these forums, and other places, in half (or quarter) for my normal 2.5g brews. I’ve been very pleased with the results.

 

[RM-MN]

Recipes scale very will but boil off is a constant. Half the ingredients and half the water may be right for you or you may find that you boil off more water than expected and end up with a smaller amount of wort that you want. That's OK, it's just water that you boiled off so add more to the fermenter to get the volume you expect.

 

[BrewingNoobing]

Tbh I havn't measured yet, it's an old one my parents had laying around.

I'd guess around 10L-15L.

 

[deeve007]

Another option which I've done successfully, is to split a 20L recipe in half and brew one after the other (either same day or next day), combining in the fermenter. Obviously the only way I could know for sure if it works as well as doing it all together would be to do a full batch at the same time as the split batch, but I can't complain with the quality of the resulting beer. My pot is around 16L and hence why I went this route myself...

I also used the no-chill method (Australian invented apparently) with the first half, added it into fermenter and then let it cool overnight, with no problems although it means that sanitation will be super important (well, I guess it is anyway).

 

[IslandLizard]

For a half batch (~10 liters of final beer) you'll need 11-12 liters in your fermenter (1-2 liters is easily lost in trub and yeast cake). You'll also boil off 2-3 liters (perhaps more depending on your setup) during an hour boil. That's beneficial as it will concentrate your wort somewhat. If you don't dump the whole kettle content into your fermenter you'll have at least 1 liter of trub left on the bottom.

(10 l) + (1-2 l) + (2-3 l) + (1 l) = 14-16 liter kettle volume needed for a "half batch."

I prefer to have at least an inch of headspace (2 inches is better) above that to limit splashing and chance of boilovers during the boil. That's probably another 2-4 liters of kettle volume needed. So that puts you at a needed kettle volume of 16-20 liters depending on those variables.

By topping up the kettle with 2nd and/or 3rd runnings while you're boiling off (evaporation) during the hour, you can get away with a somewhat smaller kettle, such as 14-15 liters.

Hopefully your kettle is at least that size. A 10 liter kettle would be too small for such a "half batch."
But you could boil in 2 kettles (on the kitchen stove) to make it work. The large one and a smaller 4-8 liter one. I sometimes boil a 2nd kettle for similar reasons. Then combine in your fermenter. Nothing wrong with that.

 

[BrewingNoobing]

Thanks for the advice, I was for sure planning on doing multiple batches and combining in my fermentor

 

[IslandLizard]

Thanks for the advice, I was for sure planning on doing multiple batches and combining in my fermentor

Good plan! It also allows you to do smaller, entirely different batches, or use different hops, etc.

Do them back to back, same day or consecutive days. Done on the same day, you can start mashing the 2nd while the first is halfway through the boil.

Multi-gyling also has the benefit of one prep and one overall cleanup, if you play your cards right.