Author Topic: Estimated pre-boil gravity is higher than estimated post-boil gravity  (Read 2778 times)

Offline switzead

  • BeerSmith Brewer
  • ***
  • Posts: 41
I did an extract batch (first time using BS software).  I added the extract to a full volume boil.  On the session tab and on the Brew Sheet the estimated pre-boil gravity is higher than the estimated post-boil gravity.  This is impossible as water is evaporated off the gravity should go up.  Below are the numbers I see in the program.  My actual pre-boil vol was 8.42 gallons at 1.039 gravity and post-boil gravity measured 1.050.  I'm sure it has something to do with my equipment setup but I cant figure it out.  Its like the software is assuming that I am doing a partial volume boil and then topping up but the est pre and post boil volumes are dead on.

Session Tab
  Est Pre-Boil Vol - 8.17
  Est Pre-Boil Gravity - 1.055
  Est Original Gravity - 1.051

Brew Sheet
  Est Pre-Boil Vol - 8.17
  Est Pre-Boil Gravity - 1.055
  Est Post-Boil Vol - 7.07
  Est Original Gravity - 1.051

Offline brewfun

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 2303
  • Malt dust is just alcohol's glitter
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #1 on: February 27, 2019, 07:16:15 AM »
The post boil gravity is what you'll measure in the fermenter, not the kettle.

The issue is in your equipment profile. You probably have top up water in it. Look in the "Post Boil and Top Up" portion of the equipment profile. This is where you're telling BeerSmith that you're adding water so that you can start with a lower pre-boil volume.
Beer Appreciation is the space between pints.

Offline switzead

  • BeerSmith Brewer
  • ***
  • Posts: 41
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #2 on: February 27, 2019, 07:24:23 AM »
Post-boil gravity in the kettle is the same as gravity in the fermenter if there is no top up.  My Top Up Water in the equipment profile is 0.0 gal.  See attached.


Offline switzead

  • BeerSmith Brewer
  • ***
  • Posts: 41
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #3 on: February 27, 2019, 07:27:38 AM »
Here are screen shots of the Brew Sheet and the Session tab.

Offline Oginme

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 3150
  • Goats, guitars, and a home brew; Life is good!
    • Longvu LaManchas
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #4 on: February 27, 2019, 07:54:24 AM »
Instead of doing screen shots, try exporting your recipe as a .bsmx file by highlighting the recipe and then clicking on 'file' > 'export selected' and saving as a .bsmx file. Post that here so that we can see how the recipe and profiles combine. It will give a much more complete view of how the program is handling your volumes and sugar balance.
Recycle your grains, feed them to a goat!

Offline switzead

  • BeerSmith Brewer
  • ***
  • Posts: 41
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #5 on: February 27, 2019, 07:59:29 AM »
See attached.

Offline Oginme

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 3150
  • Goats, guitars, and a home brew; Life is good!
    • Longvu LaManchas
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #6 on: February 27, 2019, 12:28:48 PM »
OK, something funky definitely going on here.  I looked hard at your recipe and then created my own to see if the issue followed.  It appears when 'extract' or 'partial mash' is selected as the recipe type.  By calculation the beginning of boil gravity of switzead's recipe should be 1.044 with the potential of the extract and the volume of water and extract combined used for the calculation.

Note that the OG calculation is correct when calculated by hand.
« Last Edit: February 27, 2019, 12:31:04 PM by Oginme »
Recycle your grains, feed them to a goat!

Offline switzead

  • BeerSmith Brewer
  • ***
  • Posts: 41
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #7 on: February 28, 2019, 11:42:47 AM »
It has something to do with the trub loss of 1.5gal.  If you reduce that to zero then the numbers fall into line.  I set that high to avoid any trub in my fermenter and give some cushion to boil off some extra in case I dont hit my mash numbers.  Not sure why this would affect the gravity like this though.  Any thoughts?

Offline dtapke

  • BeerSmith Grandmaster Brewer
  • *****
  • Posts: 452
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #8 on: February 28, 2019, 12:29:54 PM »
shouldn't cause this, it's clearly a glitch/issue. Try sending Brad an email unless you already have, he should be made aware of it. I've also found this when doing the same thing as Oginme.
32g eHERMS
Drinking: Dopplebock, NEIPA, Pils
Primary: empty
Secondary/Lagering:
Next Brew: RIS

Offline switzead

  • BeerSmith Brewer
  • ***
  • Posts: 41
Re: Estimated pre-boil gravity is higher than estimated post-boil gravity
« Reply #9 on: February 28, 2019, 01:52:57 PM »
I did send this to Brad before I came here.  He responded like there was no issue and then when I explained further and sent him the bsmx file, all communication stopped.  Thats why I decided to come here to see if I was doing something wrong.

 

modification