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Est Pre-Boild Gravity

x3la

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Why does "Est Pre-Boil Gravity" change when the "Boil Time" is changed on the "Design" tab?
 

Oginme

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Because BeerSmith back calculates the gravity reading from the fermenter, if you change the boil time the program is looking for the same gravity into the fermenter and with the reduced/increased boil off volume will reflect that in the change in the preboil volume and gravity target.

At least for my processes (and they have all followed the same pattern), my mash efficiency stays somewhat the same and my brew house efficiency changes as a result of the change in volumes from the mash.  So when making a change in boil time or process losses, I always go back and change the brew house efficiency to achieve close to the same mash efficiency estimation from the software.  This practice has always gotten me very close when I make process changes.
 

Oginme

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What was your pre-boil volume?  Pre-boil gravity?  How well dialed in is your equipment profile?  Are you taking your pre-boil gravity on hot wort and then correcting for temperature (because that also introduces some error)?
 

BOB357

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amelbeach1 said:
Brewed an IPA this weekend on my Robobrew, I took a pre-boil reading (after stirring the wort and adjustment for temperature) with a hydrometer and it was spot on what beersmith said I should have gotten. However after my 60 minute boil the OG was 10 points off, and I got exactly 5.5 gallons into my fermenter with minimal wort left in the kettle. Would think that boiling a wort with a specific pre-boil gravity would result in close to what beersmith would have said. My only though is that maybe the wort in the fermenter wasn't completely mixed as the sample I drew off the bottom was lower and almost the same as pre-boil and the sample i drew off the top was the 1.060 below,

Looks like you answered your own question. If the readings from the top and bottom of wort were different, either the wort wasn't well mixed or there was measurement error involved. Also, "minimal", as you describe the volume of wort left in the kettle, is not an accurate measurement.
 

jomebrew

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this account. amelbeach1, is suspicious...
 

brewfun

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jomebrew said:
this account. amelbeach1, is suspicious...

Seems confirmed, considering the insertion of a spam link one day after your concern was raised.
 
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