Boil size instead of batch size

Discussion in 'General Brewing Discussions' started by Toombstone, Jul 4, 2019.

  1. Toombstone

    Toombstone New Member

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    Can anyone explain the difference please, between boil size and batch size?

    When I enable this option. my recipe often fails the style because of a lack of ABV, I'm just wondering if I should use it or leave it? Is one more accurate I wonder?

    upload_2019-7-4_14-32-42.png

    Cheers
    Rob
     
  2. Nosybear

    Nosybear Well-Known Member

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    Your batch may have losses or other reasons for being smaller than your boil size. "Boil size" is the amount of wort you put in the kettle to boil. "Batch size" is how much wort you put into the fermentor. The difference is math is using batch size calculates boil size by adding in evaporation, other losses, etc. Using boil size just does the same thing but instead subtracts the losses.
     
  3. Toombstone

    Toombstone New Member

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    Thanks @Nosybear , so using batch size is a much more accurate calculation?
     
  4. Craigerrr

    Craigerrr Well-Known Member

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    I don't understand exactly what the check mark in that box does, but it sounds like maybe it is doubling up on your evaporation.
    The actual evaporation is only happening once in practice, so you would be 3.7L over on your volume, which may explain the lower gravity.
    May I suggest that you not use the "Brand" selection, and just enter your various losses, efficiency, etc.
    If you start by using some general rule of thumb numbers, you can then make adjustments to fine tune things.

    Following is my equipment profile for reference.

    EQ Profile.JPG
     
  5. Craigerrr

    Craigerrr Well-Known Member

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    Now I get it, did a little test, if you select a "Brand" of system all of your losses are calculated, including your boil off rate. So if you then add a boil off loss factor into the profile, you are in effect adding that much more water volume to your total mash volume number. This IS where your issue is with your drop in ABV. Go back into your equipment profile and delete any loss values you have entered.
     
  6. Craigerrr

    Craigerrr Well-Known Member

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    Okay, sorry, after some playing around with it, I see that it does affect my recipes, so I no idea what that check box is for.
    What I can tell you is that I have mine unchecked on all of my recipes and I come very close to numbers consistently.
    So, just uncheck it and forget about it would be my recommendation.
     
  7. Nosybear

    Nosybear Well-Known Member

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    I use batch size because it calculates back to the boil size, makes more sense with my process. If you had a fixed wort quantity going into the kettle, say a volume restriction, I could see calculating the other direction.
     
  8. Ward Chillington

    Ward Chillington Well-Known Member

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    #8 Ward Chillington, Jul 9, 2019
    Last edited: Jul 9, 2019
    Toomb, take a read on this thread. I think it's what you are dealing with...

    https://www.brewersfriend.com/forum/threads/how-to-deal-with-boil-off-to-get-the-target-yield.10017/

    Your mileage may vary given your brewing process, IOW, if your are a dumper, then there's no whirlpool or kettle loss because you are putting all of the post boil wort into your fermenter, Now this may increase your trub loss as you will certainly have more in your carboy. In my short time of brewing I can say that the more you repeat and learn from each batch you brew, you will be getting within plus or minus a pint in your target batch.
     

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