Pre Boil Volume Too High- Equipment Settings (Grain Absorption)

Discussion in 'General Brewing Discussions' started by MrEggSandwich, Sep 14, 2018.

  1. MrEggSandwich

    MrEggSandwich New Member

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    Hello Hello.

    Love the Brewers Friend. Great tool.

    My pre-boil volume is consistently high by 1+ gallons, assuming I need to adjust grain absorption setting. Currently its .5 qt/lb. Standard batch size is 7 gallons.

    What should I adjust it to? Someone do the math for me. Please.

    Thanks!
     
  2. philjohnwilliams

    philjohnwilliams Well-Known Member

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    A little more info on your process would be helpful. Are you doing BIAB, batch sparge or fly sparge? Without knowing anything more about your process I would think cutting your sparge volume by 1 gallon would be your best bet.
     
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  3. J A

    J A Well-Known Member

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    I count my grain absorption at .3 qts/lb and it treats me right. I'd say your setting is high there but it probably won't account for a gallon.
    You have the option of stopping when you get to your desired pre-boil volume if you're doing a fly or batch sparge, though it may negatively effect efficiency. I you're consistenly over, try sparging with a gallon less, as suggested^^^, and leave it at that. If you feel like you're still getting good gravity at the end of your sparge now, cut a gallon out of your total mash water. Or, for that matter, you don't mention what your pre-boil volume actually is, but maybe you just need to boil a helluva lot harder. :)
    Without a lot more info, it's hard to narrow things down much.
    I start with around 16 gallons total liquor and end up with around 6 gallons for sparge to get 13.5-14 gallon pre-boil on 11 gallon batches if that gives you a helpful data point.
     
  4. philjohnwilliams

    philjohnwilliams Well-Known Member

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    This is how I calculate my water. These numbers are based on the following:
    - I want to have 26qt in my kettle at the start of boil
    - I mash at a rate of 1.5qt per pound of grain
    - My mash tun has a 2qt dead space
    - .5qt per pound grain absorption works for me.
    So if I am brewing a beer with an 11 pound grain bill I will need:
    - 16.5qt strike water (11 pounds grain x 1.5qt/pound)
    - Grain absorption will reduce this volume to 11qt ( 16.5qt - (.5qt/pounds x 11 pounds) )
    - Dead space will rob me of two more quarts, leaving me with 9 ( 11-2)
    - With 9 quarts left after losses to grain and dead space, I am now 17qt shy of my 26 qt target
    - I now know that to hit my target volume I need 17qt of sparge water, and I have found I can use it with either batch or fly spargeing.

    Is this the best way to calculate your water? Probably not. But it works very well for me, I am always within a quart of my target volume.
     
  5. Ozarks Mountain Brew

    Staff Member

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    I have a 3 pot herms and it's a little different so this is what I do I mark the spot where I need to end my boil and that's it, nothing else matters except that mark, boil times don't matter, when it hits that mark it's done

    "disclaimer" although I have my profile set up perfect and I know my system like the back of my hand
     
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  6. J A

    J A Well-Known Member

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    But surely you're using boil time to figure hop additions so I imagine your boil time doesn't vary from what you intended for a particular recipe.
     
  7. Ozarks Mountain Brew

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    most of my hop additions are in the whirlpool that you taste the bittering is set
     
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  8. White Haus Brews

    White Haus Brews Active Member

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    I'd be happy to help with your math but need your numbers. From your profile it looks like you use the BrewEasy system which I believe is similar to BIAB, with your last brew day here's what we'd need to know:
    Volume of water brought to strike temp (vStrike)
    Weight of grain (Wt)
    Volume of water post mash (vPost)

    To get your grain absorption you would take
    (vStrike-vPost)/Wt

    Example: 9 gal strike water mashed with 10lb grain ending up with 8 gal post mash
    (10-9)/10 = 0.1gal/lb grain or 0.4 qts/lb
     
  9. MrEggSandwich

    MrEggSandwich New Member

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    Hi all-

    Think I got it. Last batch, my grain bill was about 20lbs.

    20*.5= 10 qts (2.5 gallons)

    If I move it down to .3= 6 qts (1.5 gallons)

    That should put me closer to right volume.
     
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  10. MrEggSandwich

    MrEggSandwich New Member

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    I used the BrewEasy.
     

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