Spike Brewing 12.5 Conical Fermenter Giveaway!

 Home Brew Forums > How does one determine the boil size?

10-25-2008, 07:14 AM   #1
Pelikan
Feedback Score: 0 reviews
Recipes

Join Date: Oct 2008
Location: The Q Continuum
Posts: 927
Liked 8 Times on 8 Posts
Likes Given: 2

 How does one determine the boil size?

So I've quickly advanced to messing around with online calculators in an effort to develop my own recipes. One of the main factors is boil size. So I'm wondering, does the size of the boil mean the volume after all the goodies are added, or the amount of water before anything is added?

I suppose I'm asking, how does one determine the "boil size" to plug into the calculator? For my purposes, I'm referring to extract plus grain.

__________________

On a brewing hiatus. Will get back into the fray eventually, methinks...

Last edited by Pelikan; 10-25-2008 at 08:12 AM.

10-25-2008, 11:41 AM   #2
Bob
Feedback Score: 0 reviews
Recipes

Join Date: Nov 2007
Location: Christiansted, St Croix, USVI, US Virgin Islands
Posts: 3,921
Liked 126 Times on 94 Posts
Likes Given: 36

Size of the boil is how much fluid is in the pot when you turn the burner on.

That, combined with the amount of extract dissolved in the fluid, allows the calculator to estimate the hops utilization percentage, which determines IBU. Say you've got 6 lbs of dry extract, 1 oz of hops at 5%AA that you'll boil 60 minutes. With a 3-gallon boil, the gravity in the kettle is 1.090, and utilization is relatively low; you'll get 13 IBUs from your ounce of hops. Increase the boil size to 5 gallons, the gravity of the boil drops to 1.054, utilization increases, and IBUs rise to 18.

Basically, theory aside, you determine boil size by the largest volume you can boil without excessive fear of boil-over. For my kettle, that's 3.5 gallons. For others, it's 15 gallons! So measure how much you can fit in your kettle. You can safely boil between 60-70 percent of that volume. For example, my kettle is 5 gallons, and I can boil 3.5 gallons safely; that's boiling 70% of the kettle capacity.

You want a vigorous, rolling boil, you see. A simmer with a couple of big "blups" now and then won't cut it. Protein- and sugar-rich fluids at a vigorous rolling boil tend to boil over and make a hell of a mess. So the size of the vessel - and therefore the size of the boil - is based on containment.

You dig?

Bob

__________________

Brewmaster
Fort Christian Brewpub
St Croix, US Virgin Islands

10-25-2008, 04:35 PM   #3
Malticulous
Feedback Score: 0 reviews
Recipes

Join Date: Aug 2008
Location: St. George Utah
Posts: 4,055
Liked 52 Times on 43 Posts
Likes Given: 62

Don't forget to leave room for late extract additions.

__________________

I think I'll have another pint of this highly flawed beer because it's so damned good.