gizzygizmo
Brewer
- Joined
- Mar 17, 2019
- Messages
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I'd like to request a variable be created to display the post-boil gravity... while the wort is still hot and hasn't shrunk yet. I've been playing with removing shrinkage to see the math that adjust volumes based on temp and I've come to the conclusion that $EST_OG is the gravity reading of the cooled/shrunk wort. Trying to match this value at post-boil will be off.
Examples...
Shrinkage removed from equipment:
1) post mash/preboil volume 8 and Gravity of 1.039
2) Post boil volume is displayed as 6.5 gallons => 8 gallons - boil off 1.5 and no shrinkage
3) OG of 1.048 is displayed
Math on this is 39 * 8 = 312 points, divided by final volume of 6.5g = 1.048, all is well.
Having a 4% shrinkage in equipment:
1) post mash /preboil volume of 8.27 and Gravity of 1.038 (i suspect because 8 gallons + 3-4% shrinkage at 150degF is 8.27 and will make the Gravity be (39*8)/8.27 => 37.72 and it rounds up to display 37.27
2) Post boil volume is displayed as 6.77 = 8.27 pre boil, minus boil off 1.5, minus shrinkage of .22
3) OG of 1.048 is displayed
Math on this is 38 * 8.27 = 312.26, divided by final volume of 6.5 = 1.048
My issue is that I like to check the gravity right toward the end of boil. So when the post boil volume is reached around 6.77 gallons i'm reading 1.046 etc, and trying to figure out why i'm short. My instinct is to do the math of "preboil OG * preboil volume / current volume" to get what my SG should be. At the end of boil I would assume i should get the OG. But the OG displayed is for chilled/cooled/shrunk wort not hot 212degF expanded wort.
My custom brewsteps currently display "measure post boil volume: " and suggest $POST_BOIL_VOLUME.
Then I have a line for "measure post boil gravity: " and i'm suggesting $EST_EG.
The $EST_EG is usually off by a bit, in one case i'm getting 1.046. Initially I thought i was off and would think i need to adjust with some DME to 1.048. If that's done then it'll chill/shrink and be at 1.049. These numbers don't seem to bad, and i never really noticed until i started doing some batches of RIS in which the values are exaggerated. A 8.27gallon volume preboil at 1.084 gives me 6.77gallons at 1.102, chilled it is 1.106. I don't swat 1 or 2 gravity points, but i want to know why i'm off by 4-5 points and the only thing I did was boil.
I would like to be able to just display the value here.. or if I could do some math somehow and display my own values that would be nice. I'd like to multiply the batch volume * gravity and divide by pre-boil volume to display a target "post boil gravity" that I can check before the wort is chilled. If any numbers are wrong "now" i can throw DME in or water and it will be sanitized by heat. If i wait until its chilled it's too late.
For now i'm just scribbling in a number, and i can do math if the volumes are off (larger/smaller preboil or post-boil than planned means I need to change the numbers anyway)
Examples...
Shrinkage removed from equipment:
1) post mash/preboil volume 8 and Gravity of 1.039
2) Post boil volume is displayed as 6.5 gallons => 8 gallons - boil off 1.5 and no shrinkage
3) OG of 1.048 is displayed
Math on this is 39 * 8 = 312 points, divided by final volume of 6.5g = 1.048, all is well.
Having a 4% shrinkage in equipment:
1) post mash /preboil volume of 8.27 and Gravity of 1.038 (i suspect because 8 gallons + 3-4% shrinkage at 150degF is 8.27 and will make the Gravity be (39*8)/8.27 => 37.72 and it rounds up to display 37.27
2) Post boil volume is displayed as 6.77 = 8.27 pre boil, minus boil off 1.5, minus shrinkage of .22
3) OG of 1.048 is displayed
Math on this is 38 * 8.27 = 312.26, divided by final volume of 6.5 = 1.048
My issue is that I like to check the gravity right toward the end of boil. So when the post boil volume is reached around 6.77 gallons i'm reading 1.046 etc, and trying to figure out why i'm short. My instinct is to do the math of "preboil OG * preboil volume / current volume" to get what my SG should be. At the end of boil I would assume i should get the OG. But the OG displayed is for chilled/cooled/shrunk wort not hot 212degF expanded wort.
My custom brewsteps currently display "measure post boil volume: " and suggest $POST_BOIL_VOLUME.
Then I have a line for "measure post boil gravity: " and i'm suggesting $EST_EG.
The $EST_EG is usually off by a bit, in one case i'm getting 1.046. Initially I thought i was off and would think i need to adjust with some DME to 1.048. If that's done then it'll chill/shrink and be at 1.049. These numbers don't seem to bad, and i never really noticed until i started doing some batches of RIS in which the values are exaggerated. A 8.27gallon volume preboil at 1.084 gives me 6.77gallons at 1.102, chilled it is 1.106. I don't swat 1 or 2 gravity points, but i want to know why i'm off by 4-5 points and the only thing I did was boil.
I would like to be able to just display the value here.. or if I could do some math somehow and display my own values that would be nice. I'd like to multiply the batch volume * gravity and divide by pre-boil volume to display a target "post boil gravity" that I can check before the wort is chilled. If any numbers are wrong "now" i can throw DME in or water and it will be sanitized by heat. If i wait until its chilled it's too late.
For now i'm just scribbling in a number, and i can do math if the volumes are off (larger/smaller preboil or post-boil than planned means I need to change the numbers anyway)