BeerSmith Equipment Profile changes IBU?

Hi,

I have been using BeerSmith for sometime quite successfully brewing All Grain recipes that I have to add top-up water to which I have added in my customized equipment profile and it all works out fine.

My concern is that I recently upgraded my brew pot to 16 Gal so that I can now do "Full Volume" boils for my 11 and 12 gal batches...
So I created a new equipment profile based on my old one and all I changed was the top-up water by putting it to 0.
When I use this profile with pre existing recipes that's I've brewed, the IBU target changes quite a bit...  is this normal?
If so is there a quick explanation as to why?

Sorry of this question may have been posted elsewhere, but I couldn't find it, so please direct me to a link if so.

Thanks much!

Cheers!

There is an explanation.  When doing partial boils, Alpha Acids are not incorporated into your wort as efficiently.  This is the reason that it is suggested that when extract brewing, you start your boil with about 1/3 of the extract and only add the remaining 2/3rds at the last 10-15 minutes of the boil.

By going to a full boil, you are now more fully utilizing the Alpha Acids in your hops and getting better extraction, because you are no longer boiling a high sugar concentrated wort.

Trust the IBU's that BeerSmith is giving you for a full boil.  The upside for you, is that now you can use less hops than you did before a save and little bit of money.

Scott Ickes said:

There is an explanation.  When doing partial boils, Alpha Acids are not incorporated into your wort as efficiently.  This is the reason that it is suggested that when extract brewing, you start your boil with about 1/3 of the extract and only add the remaining 2/3rds at the last 10-15 minutes of the boil.

By going to a full boil, you are now more fully utilizing the Alpha Acids in your hops and getting better extraction, because you are no longer boiling a high sugar concentrated wort.

Trust the IBU's that BeerSmith is giving you for a full boil.  The upside for you, is that now you can use less hops than you did before a save a little bit of money.

Click to expand...

Thanks Scott, I actually think I get it!  Good explanation and much appreciated!

Cheers!
Frank