Author Topic: Batch size vs. Estimated post boil volume  (Read 25487 times)

Offline dmbnpj

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Batch size vs. Estimated post boil volume
« on: December 10, 2011, 04:45:12 PM »
For a typical 5 gallon batch, why does beersmith kick out a post boil volume of 6.24 gallons? And then after it says to transfer to fermenter, it says to add water to achieve 5 gallons?

Offline tom_hampton

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Re: Batch size vs. Estimated post boil volume
« Reply #1 on: December 20, 2011, 11:15:43 AM »
Boil off, and losses due to wort transfer / trub.  I prefer not to add water post-boil....to much trouble to get sterilized water.  So, I adjust all my preboil volume losses in order to ensure that I have plenty going into the carboy/bucket.  I lost 1.0 gallons per hour in my old 8 gal SS pot...its higher now, as I just switched to a keggle with its larger diameter (and much larger surface area).  I haven't figured out my new boil-off rate for the keggle.  So, I would think 6.25 into the kettle would be a little low, and you probably will lose more than 1.25 gallons before you get to the fermenter.

I prefer to ferment 6 gallons and bottle whatever doesn't fit into the keg.  I have over 8 gallons going into the kettle and expect to lose ~2.5 gallons....most due to boil-off.  In addition, I use whole leaf hops, and I loose some wort due to leave absorption.
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Offline HolyFirkins

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Re: Batch size vs. Estimated post boil volume
« Reply #2 on: January 19, 2012, 11:15:56 AM »
Boil off, and losses due to wort transfer / trub.  I prefer not to add water post-boil....to much trouble to get sterilized water.  So, I adjust all my preboil volume losses in order to ensure that I have plenty going into the carboy/bucket.  I lost 1.0 gallons per hour in my old 8 gal SS pot...its higher now, as I just switched to a keggle with its larger diameter (and much larger surface area).  I haven't figured out my new boil-off rate for the keggle.  So, I would think 6.25 into the kettle would be a little low, and you probably will lose more than 1.25 gallons before you get to the fermenter.

I prefer to ferment 6 gallons and bottle whatever doesn't fit into the keg.  I have over 8 gallons going into the kettle and expect to lose ~2.5 gallons....most due to boil-off.  In addition, I use whole leaf hops, and I loose some wort due to leave absorption.

exactly..my only question/statement is shouldn't "batch volume" be what you are left with after bottling/kegging? a 5 gallon batch means you are making 5 gallons of drinkable beer. yet, beersmith defines "batch volume" as what you put into the fermenter. so in order to change what goes into the fermenter, the entire recipe is changed. and what also doesnt make sense is if the batch volume is 5 gallons (which is what they say is in the fermenter) then there is no way bottling volume can/should be the same. if i change batch volume, then the bottling volume changes to the same number..should not be..i start with 7 gallons in the kettle, throw in 5.5-6 gallons after boiling and chilling and any other losses..lose a half gallon to trub, which leaves me with 5 gallons to bottle..according to beersmith i made a 6 gallon recipe, but in reality i made a 5 gallon recipe. i'm hoping this gets fixed/switched so that i can say "this is a 5 gallon recipe" meaning that is what i am left with after bottling to be able to drink..
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Offline harbourn

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Re: Batch size vs. Estimated post boil volume
« Reply #3 on: January 29, 2012, 07:28:16 PM »
I recently upgraded to beersmith v2 and noticed this same issue (i.e. it telling me I need to draw 7.89 gallons of wort to be able to put 5.5 gallons into the fermenter). I've been able to work around it as I will describe, but I think it is a terminology problem now in the program. According to the tool tip label the batch size amount should be how much liquid you transfer to your fermenter. This currently is not the case, but we can cheat it back to normal.

If you go to the Water Vols tab in your recipe you'll see v2 adds some new fields where you can track and plan for specific losses through your process. Specifically, Boil and Fermentation then Fermentation/Bottling. With all default settings the program will start with the values 1 Gallon for loss in Boil and Fermentation and then .75 Gallon loss under Fermentation/Bottling.  The Fermentation/Bottling values are really just a handy calculator and won't adjust the water levels in your recipe by changing them. The Boil and Fermentation section though is used when calculating your required water levels. The problem child value is the field labeled "Trub Loss". I could be wrong but this sounds to me like a post-fermentation loss but BeerSmith v2 subtracts this early, as if you left it in the boil kettle (the cooling loss value in there i believe already accounts for that). If you set this Trub Loss value to zero everything will make sense again in beersmith.

TL;DR version
it seems like a bug, for now go to the water levels tab in your recipe and set "Trub Loss" to zero

maddspoiler

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Re: Batch size vs. Estimated post boil volume
« Reply #4 on: January 31, 2012, 10:07:24 PM »
BATCH MEANS VOLUME INTO FERMENTOR!

Offline MaltLicker

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Re: Batch size vs. Estimated post boil volume
« Reply #5 on: February 02, 2012, 08:54:00 PM »
Quote
......exactly..my only question/statement is shouldn't "batch volume" be what you are left with after bottling/kegging? a 5 gallon batch means you are making 5 gallons of drinkable beer. yet, beersmith defines "batch volume" as what you put into the fermenter. so in order to change what goes into the fermenter, the entire recipe is changed.

Brewing to reach a specific gravity wort with a certain volume of wort is one of getting the concentration of sugars correct.  A cup of espresso and cup of weak coffee might have the same amount of coffee grounds, but one is highly concentrated and one very diluted. 

That's the objective on brew day: to finish with that exact concentration of sugars (SG) in the amount of wort needed to fill the fermentor to our desired level.  Your EE% estimates the total sugars you'll rinse out, but it is the amount collected that determines the concentration (SG).   Ever over-collected, and then boiled longer to re-concentrate the wort?   That is a good illustration of 'batch volume' at work. 

If we hit that 'concentration' target, then we get the beer we wanted, and whether it fills 48 or 51 bottles is determined on bottling day.  For ex, what if you spilled half the bottling bucket on the floor and finished with 24 bottles?  The OG and FG are unchanged, and you still have 24 bottles of wort/beer of the perfect concentration you aimed for.   What gets packaged is largely independent of brew-day math, other than padding your batch volume to ensure you reach your packaging goal.   

That is also why telling BeerSmith all your typical losses is vitally important.  BeerSmith assumes everything that goes in will come out, so losses must be factored in to get the concentration correct.  Underestimate trub losses, and the wort is weaker because it is diluted across more wort that BSmith did not know about (i.e., bottom of the keg), just like making espresso in too-large a cup.