Boil Gravity to Original Gravity

Discussion in 'Brew Sessions' started by mengelma, Oct 25, 2016.

  1. mengelma

    mengelma New Member

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    Hello All,

    I have been using Brewers Friend for 1+ years, doing all grain 10 Gallon batches.

    Just got a refractometer to check preboil gravity, etc.

    Brewed Yoopers Oatmeal stout last weekend, to the base recipe (fantastic).

    Advance Recipe options and stats shows 'boil gravity' of 1.044. and 'original gravity' of 1.056.
    1) Trying to understand if 'boil gravity' in advanced recipe is equal to pre boil efficiency in brew log.
    2) increase from 1.044 to 1.055 seems way to much for a one hour boil at boil off rate of 1 gal/hr

    Actual results:
    1) Pre boil gravity via refractometer (brew log) 1.043
    2) Original gravity 1.052 (hydrometer)


    Bottom line trying to understand relationship of boil gravity to original gravity.

    Thanks all
     
  2. Yooper

    Yooper Administrator
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    Hmmm, that does seem like a huge change. What is your preboil volume vs your post-boil volume in the software?
     
  3. Ozarks Mountain Brew

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    thats all relative to your settings in your profile, you set your losses, are you brewing someone else's recipe or creating your own using your kettle and losses in the recipe
     
  4. mengelma

    mengelma New Member

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    Preboil volume is 13.7 gal
    Boil off set to 1 gal / hour (Keggle)
    Fermenter target 11.0 gal (achieved)
    dead kettle set to 1.5 gal

    Recipe for this batch was updated from my initial recipe input from about 9 months ago. I have been tweaking profiles as I go.

    I think I am missing the starting gravity due to the amount of dead kettle I have set, but I thought the software would adjust.

    Still would like to know what the boil gravity in the recipe editor is equivalent to in efficiency calcs.

    Thank you all for your input. I really appreciate it.
     
  5. Yooper

    Yooper Administrator
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    You did a one gallon boil off? And you lost one gallon to evaporation, and 1.5 to "dead kettle"? Remember that all of that trub loss means that you are throwing away like 20% of your wort. I think that's the issue- you shouldn't have 11 gallons to the fermenter if you start with a nearly 14 gallon boil and only boil off 1 gallon per hour. That may be where the preboil SG and then the post boil SG predictions fail.
     
  6. mengelma

    mengelma New Member

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    You are right on, as I tweak the dead kettle amount in the numbers comes into line. My other error was to use 70% brew house efficiency with so much extra water, could never get to 70%

    My early batches had a lot of trub, now have a recirculating mash pump and used rice hulls last time and the kettle was very clean. So I will dial way back the dead kettle.

    As an enhancement the software could have calculated the maximum brew house efficiency given my inputs and flagged that I would never get to 70% brew house efficiency.

    Good day....learned something!
     

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