(RESOLVED) PPG loss in boil?

Discussion in 'Brew Sessions' started by Head First, Mar 21, 2013.

  1. Head First

    Head First Well-Known Member

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    Working on tweeking my efficiency and am loosing ppg's in the boil down (between pre-boil and ending kettle. Is this possible? Hydrometer readings are always up. Am I comparing apples to oranges?
     
  2. Kaiser

    Kaiser Member

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    Re: PPG loss in boil?

    No, this is not possible. How are you taking your pre-boil and post boil readings? If you cool any of them they have to be cooled in a closed container to eliminate evaporation.

    Kai
     
  3. Head First

    Head First Well-Known Member

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    Re: PPG loss in boil?

    Sugar evaporates?
     
  4. LarryBrewer

    LarryBrewer Active Member

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    Re: PPG loss in boil?

    You shouldn't be loosing any ppg during the boil.

    Do make sure that your hydrometer readings are temperature corrected - thought I'm sure you've seen that already.
     
  5. Head First

    Head First Well-Known Member

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    Re: PPG loss in boil?

    With an Irish ale
    My pre-boil was 1.046 @ 70 deg 56qts- Brew log shows 82% 29.8ppg
    My boil complete was 1.050 at 70 deg 46qts Brew log shows Ending kettle 73% 26.5ppg
    With a Robust Porter
    My pre-boil was 1.048 @ 82 deg 51.2 qts Brew log shows 91% 32.8 ppg
    My boil complete was 1.063 @ 73 deg 44 qts Brew log shows Ending kettle 80% 30.1ppg
    The porter had 2#s of brown sugar added in beginning of boil which is included in that pre-boil gravity.
    I realize the sugars can change things and am ignoring the efficiency's in analyzing this but I am sure my readings are correct as far as hydrometer. We have 4 and the 1 used is spot on.
    We have several thermometers and the lab type used checks out at freezing and boiling spot on.
    I'm trying to see if there is some other info I'm entering that could cause the software to spit these #s out. Does it reduce anything from my profile other than evaporation during this step? How can I lose sugars in a boil down?
     
  6. LarryBrewer

    LarryBrewer Active Member

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    Re: PPG loss in boil?

    The pre and post boil gravities in terms of dilution and boil off are not lining up - and this is independent of any software package, so let's try to figure that out first. Basically, I think as you understand, if you boil 10 gallons of wort starting at 1.040 down to 5 gallons, the resulting gravity will be 1.080. We should be observing the same pattern in your measurements.

    The dilution calculator, 2nd section, comes up with the following:
    http://www.brewersfriend.com/dilution-a ... alculator/

    Irish ale: Boil 56 qts @ 1.046 down to 46 qt = 1.056 expected resulting gravity
    Porter: Boil 51.2 qts @ 1.048 down to 44 qt = 1.056 expected resulting gravity

    You got 1.050 and 1.063 respectively, those are both off, and in different directions. That tells us something is amiss +/-0.007.

    Other things to check:
    Are the gravities and volumes given both temperature corrected?
    1.048 @ 82F is actually 1.050 on a hydrometer calibrated to 60F.
    Are you using a sight gauge on your kettle? Boiling wort is about 4% higher in volume, so if you are comparing one volume at boiling, and one volume chilled, it isn't apples to apples.
    Are you adding anything to the kettle like sugars or water (except hops) during the boil that would alter the boil off dilution ratio?

    About raw sugars in the boil:
    The batch stats logic expects that raw sugars are not present for the pre-boil gravity reading, but are included in the boil complete reading. This is not related to the boil off gravity change inconsistency we are seeing.

    In addition, profile settings would not impact this, except your cooling shrinkage factor.
     
  7. Head First

    Head First Well-Known Member

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    Re:(Found it) PPG loss in boil?

    I very much appreciate your time and patience LB. You pointed me in the right directions. I was noticing the drop in ppg's and thinking they were related but couldn't find a common factor that caused it. That's cause it wasn't the same mistake.Temperature corrections and volume number transfers were to blame. They are corrected now. My other recipes were coming out fine. All recipes have made 99% to 102% conversion and are comparable with ppg status throughout the process. Boil down volumes seem to vary some though, so I may watch my volume rather than just the clock. All batches are boiled 90 min. so 10 or 20 min. one way or another should help with that. Propane burners are not an exact science. My brew house still remains in mid to high 70's so I am ok with that for now. Sure was a lot easier to brew without this software stuff :geek: . But better beer is worth every drop of sweat :D .
    Thanks again.
     
  8. LarryBrewer

    LarryBrewer Active Member

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    Re: PPG loss in boil?

    Glad the mystery is solved, and happy to help!
     

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