Confused by Boil Gravity vs OG

[CJ]

I'm playing with a DIPA recipe I'm brewing tomorrow, but the boil gravity estimate is confusing and worrying me. The recipe is http://www.brewersfriend.com/homebrew/recipe/view/62146/pliny-in-dumnonia.

I can't see how I'm going to reach my OG of 1.072 when the boil gravity is only estimated at 1.049. Doing the maths, 27.2L of water in the kettle x 49 pts = 1348 pts. Divide that by the volume at at the end of the boil (so the only thing to subtract here is boil off - 5L) = 1348/22.2 = 1.060.

I'm quite worried that I'm not going to hit my OG target... Am I being an idiot?

 

[LarryBrewer]

The recipe thinks the boil off is 27.5 - 19 = 8.5L, not 5L. The extra 3.5L must be kettle dead space and hops absorption?

What you can do is set the batch size target to 'kettle', and then update batch size to 22.5. To the kettle batch size is the way to go in this case, and it is what a lot of advanced brewers use.

For future reference, we have a handy dilution calculator (the 2nd box is what I used to double check the numbers):
http://www.brewersfriend.com/dilution-a ... alculator/

 

[CJ]

I see! Thanks man, I knew it was me being daft! You're right about kettle dead space and absorption. I had thought the calculator would take these into account though.

 

[LarryBrewer]

I see! Thanks man, I knew it was me being daft! You're right about kettle dead space and absorption. I had thought the calculator would take these into account though.

The water requirements is a level deeper than the recipe info. The recipe editor does not adjust the recipe batch size in fermentor mode, though it could down the road. There are so many brewing processes to worry about - straining wort, whilpooling, etc. I drain my kettle which has an internal dip tube and leave behind 1-2 quarts. On IPAs, I squeeze out the hops bags, so hops absorption is not a factor. You may want to squeeze out your hops on this brew:
http://www.brewersfriend.com/2013/05/10 ... ss-please/


'To the kettle' batch size is way more portable between different brewers for these reasons. The water requirements will report the estimated amount of wort you will get in the fermentor.