half batch full boil same as full batch partial boil?

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Firechicken

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So I found a recipe on my online brewstore I want to try. It like many is setup for a 5 gal brew and I want to do 2.5 gal. From what I read I can simple just cut all the ingredients in half. Easy enough. However, the instructions for the 5 gallon brew state to partial boil at least 3 1/2 gallons then add water in fermetor etc to get to 5 gallons etc. If I start with about 3 1/4 (would prob boil down to about 2.5) gallons and do a full boil and follow the exact instructions with half the amount of ingredients will I get the same end result as the 5 gallon batch? In theory I should correct? Also yeast. Seems there is some mixed opinions on if its ok to pitch a full 5 gallon batch pack of yeast into a 2.5 gallon brew or to cut in half. Thoughts? A full pack will just ferment quicker and prob taste better, yes?
 
A "full boil" is better than a "partial boil" either way. You get better hop utilization. So typically, if you have the means, and pot space, it's better to do a "full boil".

Yeast is a little different. There are some differing opinions, but overpitching isn't necessarily a good thing. There is some benefit to allow the yeast to be able to reproduce and not just have an abundance to being with. I don't know if "cut in half" is the best way, but you could use a yeast calculator and get a pretty good idea.
 
You'll probably get slightly more IBUs going a full boil, but probably not so much that it is worth worrying about (unless the recipe calls for quite a large 60 minute addition). If you are curious, input the recipes into some brewing software to see if the difference is something you want to worry about. Other than that, your assumptions are all good in terms of cutting the recipe in half.

For the yeast, I'd check http://www.mrmalty.com/calc/calc.html. I would argue that a single vial of liquid yeast is usually NOT enough for a full 5 gallon batch, so 1/2 a vial would not be enough for a 2.5 gallon batch. Not sure about dried yeast, but the pitching rate calculator will tell you.
 
3.5 Gallons is a pretty big boil if you aren't setup for it - that in a 5 gallon kettle would likely take some technique to avoid boilovers - I'd perhaps even if go with some kinda foam control. 3.25 is not far off. Depending on your kettle, wort gravity, etc. I always find that 3 gallons in a 5 gallon kettle is nice, even a little more, and depending on the beer you are brewing, you'll be doing a boil-over-is-coming dance.

Once you've established that you are ready to boil that kind of volume, your 2.5 gallon (final boil vol) will act exactly as partial boil. The yeast you should look at in terms of cells, not packages. Use the yeast calculator and follow the cell guidlines - over pitching a little is fine, a lot my not be.

What gravity and what beer?

EDIT - I'm guessing that if you can't quite boil the full 3.25 gallons or whatever it would take to get the 2.5 final vol, boiling 3 gallons into whatever it works out to be and then adding a very small amount of top off water seems like it would work almost as a full boil with a VERY slight difference to me.
 
J187 said:
3.5 Gallons is a pretty big boil if you aren't setup for it - that in a 5 gallon kettle would likely take some technique to avoid boilovers - I'd perhaps even if go with some kinda foam control. 3.25 is not far off. Depending on your kettle, wort gravity, etc. I always find that 3 gallons in a 5 gallon kettle is nice, even a little more, and depending on the beer you are brewing, you'll be doing a boil-over-is-coming dance.
Click to expand...

Definitely depends on the setup. I routinely boil 2.5 gallons in a 3 gallon pot in my electric stove. I have to be ready for the foam up and pull it off the heat for a few seconds until it subsides, but only for the first 2-3 minutes at the start of the boil. Not sure if I could do this with a 5 gallon kettle, but it might definitely be doable.
 
JLem said:
You'll probably get slightly more IBUs going a full boil, but probably not so much that it is worth worrying about (unless the recipe calls for quite a large 60 minute addition). If you are curious, input the recipes into some brewing software to see if the difference is something you want to worry about. Other than that, your assumptions are all good in terms of cutting the recipe in half.

For the yeast, I'd check http://www.mrmalty.com/calc/calc.html. I would argue that a single vial of liquid yeast is usually NOT enough for a full 5 gallon batch, so 1/2 a vial would not be enough for a 2.5 gallon batch. Not sure about dried yeast, but the pitching rate calculator will tell you.
Click to expand...

Thanks for the yeast calc. This should work great!

J187 said:
3.5 Gallons is a pretty big boil if you aren't setup for it - that in a 5 gallon kettle would likely take some technique to avoid boilovers - I'd perhaps even if go with some kinda foam control. 3.25 is not far off. Depending on your kettle, wort gravity, etc. I always find that 3 gallons in a 5 gallon kettle is nice, even a little more, and depending on the beer you are brewing, you'll be doing a boil-over-is-coming dance.

Once you've established that you are ready to boil that kind of volume, your 2.5 gallon (final boil vol) will act exactly as partial boil. The yeast you should look at in terms of cells, not packages. Use the yeast calculator and follow the cell guidlines - over pitching a little is fine, a lot my not be.

What gravity and what beer?

EDIT - I'm guessing that if you can't quite boil the full 3.25 gallons or whatever it would take to get the 2.5 final vol, boiling 3 gallons into whatever it works out to be and then adding a very small amount of top off water seems like it would work almost as a full boil with a VERY slight difference to me.
Click to expand...

Good to know! Im planning on a Black IPA. OG 1.070

I think I'll do 3 gallons or maybe a tad less and see how that responds for my first batch. If I have to add a half gallon or so of water after to get 2.5g I will. I agree, I dont think it will make a big difference.
 

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