Does it matter how much water I boil?

[sleepylight]

I'm making an IPA from an extract kit which is set up for a 2.5 gallon boil, with 2.5 gallons of water to be added after the boil, for a typical 5 gallon batch. My kettle is large enough to easily boil 5 gallons, and I've been told that it really doesn't matter when the water gets added, as long as the gravity is correct for the recipe.

So, before I jump into this batch I looked at the instructions and it says if I boil more that 2.5 gal, it will increase the IBU, and less than 2.5 will decrease the IBUs. Is that accurate?

-Max

 

[Yooper]

I'm making an IPA from an extract kit which is set up for a 2.5 gallon boil, with 2.5 gallons of water to be added after the boil, for a typical 5 gallon batch. My kettle is large enough to easily boil 5 gallons, and I've been told that it really doesn't matter when the water gets added, as long as the gravity is correct for the recipe.

So, before I jump into this batch I looked at the instructions and it says if I boil more that 2.5 gal, it will increase the IBU, and less than 2.5 will decrease the IBUs. Is that accurate?

-Max

In general, "bigger is better". If you can boil, say, 4 gallons, the beer will be a little less carmelized and "extract-y". If you can boil 5 gallons (and cool 5 gallons), then I'd boil all that I could. The beer will be greatly improved.

You don't have to worry about hops utilization- it's really independent of boil gravity and for an IPA you especially don't have to worry about it.

 

[Calder]

You don't have to worry about hops utilization- it's really independent of boil gravity and for an IPA you especially don't have to worry about it.

I don't believe that has been proven to be true. Conventional wisdom (which is being questioned) is that higher gravity = less IBUs for a given amount of hops.

Pick any brewing program, and input the numbers and they will all show increased IBUs with lower gravity worts. Are they all wrong?

At some point there was some science behind the IBU calculations of Rager, Tinseth, and Garetz .... although all wildly different bringing into question the accuracy of any of them, all of them are consistent in their adjustment for wort gravity.


To the OP: Larger volume boil will give you a better beer. If it also gives you higher IBUs ...... well, it is an IPA, and the hallmark of IPAs is high IBUs.

 

[Yooper]

Pick any brewing program, and input the numbers and they will all show increased IBUs with lower gravity worts. Are they all wrong?

In short, yes. Even John Palmer says he was wrong in his book (How to Brew) and states that while break material may impact hops utilization some, that extracting IBUs is independent of wort gravity. Most of this is "new", since about 2008, but you'll find plenty of reading on it if you choose!

 

[ResumeMan]

Hop utilization aside, the one thing I'd make sure you consider is Yooper's parenthetical "(and cool 5 gallons)". The more liquid you boil the more you need to cool to pitching temperature. An ice bath for that much boiling liquid would be a bit of an adventure, so make sure you've got a plan for that aspect of the process.

Edit: boy I've been out of the brewing loop too long. I had no idea that the gravity/isomerization relationship was now in dispute.

 

[BamaRooster]

The cooling plan is important. It's best to boil 5 gallons but unless you have a process to cool the wort quickly, it might be better to boil a smaller volume. Since I do not yet have a chiller, I do boil 3.5 gallons and top off with chilled water after an ice bath.