1 to 2 vessels migration

[FunkedOut]

I need a hand wrapping my head around moving from single vessel BIAB to a 2 vessel rig.
Particularly setting up the mash profile in BeerSmith.
Not sure if this a process misunderstanding or a software misunderstanding.
Let me explain what's got me confused...

I took a recipe from a recent brew and changed the mash profile from a BIAB single infusion, to a single infusion, no sparge, no mash out profile that came as a sample.
I can see where the Total Water Needed field increased by exactly the amount of difference in the grain absorption rates.
What confuses me is that the calculated/estimated post mash gravity and pre-boil gravity don't change.
In my mind, there is wort left in the grain, not water.

If I mashed this BIAB-style, then lifted the bag out and and squeezed until exactly 0.586 fl.oz. of wort was left in the bag per every oz. of grain (BS default for BIAB), my mind tells me that the wort left in the grain in the bag shares the same SG as the wort in the kettle.
Many times, I've lifted the bag, stirred well, measured the gravity, then squeezed the bag for another half gallon, stirred and measured the same gravity.

So If I now mash this same grist, with the increased amount of water described above, in a mash tun with false bottom, full volume, and simply drain.
I'll take a leap of faith here (since I've never done it) and assume that the grain will hang on to 0.96 fl.oz of wort for every oz of grain (BS default for non-BIAB).
My mind tells me that I have diluted this wort by the water addition and the gravity should be lower. Something like this:

(BIAB Volume of Water)*(BIAB Post Mash Gravity) = (nonBIAB Volume of Water)*(nonBIAB Post Mash Gravity)

However, BS doesn't change its estimated power mash gravity or pre-boil volume when switching from BIAB mash profiles to nonBIAB mash profiles.

Am I doing something wrong in BS?
Or is my mind playing tricks on me with regard to the added water = dilution concept?

Thanks for reading all that.

 

[FunkedOut]

'moved' this to brewing software section:
https://www.homebrewtalk.com/forum/threads/1-to-2-vessels-migration.647851/

I'm feeling fairly confident this is a software issue.

 

[FunkedOut]

maybe not so sure...

i just plugged these numbers into brewersfriend.com's online recipe builder: https://www.brewersfriend.com/homebrew/recipe/calculator
and got the same results as BeerSmith.

Either both calculators are treating what's being absorbed by the grain as water with no sugar,
or my understanding of what's going on is off.

At first glance (of real world, not the BS model), it seems that BIAB is inherently more efficient than no sparge brewing, because less wort (water & sugar) is left in the grain.

 

[FunkedOut]

a few brews in (myself, not the new rig)...

it's not worth chasing. i'll just brew on the new rig and walk the efficiencies in.

 

[madscientist451]

I use a 2 vessel setup, what's the recipe?
And what is your boil off rate (evaporation) per hour?

 

[FunkedOut]

Recipe and boil off rate will not make a difference in this discussion.
Appreciate your interest and another set of eyes, so here you go:

100% pale malt to 1.054 OG
boil off rate = 1 gallon per hour

 

[wilserbrewer]

Why wouldn’t you squeeze the bag a second time and just use the same
Absorption rate?

 

[FunkedOut]

Great question.
I am exploring results that would come from not lifting and squeezing the bag at all.

Formerly full volume BIAB, with a lift and squeeze.
Going to a full volume mash tun with drain (no lift, no squeeze).

Apologies for the long OP.

 

[madscientist451]

So....Can you explain what it is that you are trying to determine? The total amount of water needed?
The OG? Sorry, I read the original question a few times and I can't figure out what you are asking.

 

[FunkedOut]

I’ll try my best (again) to be succinct.

Brewed a recipe BIAB.
Now modeling that brew as a full volume mash in a tun, rather than in a bag.

More water absorption by grain.
More water added to compensate.

Why does software model not decrease gravity or increase efficiency?

 

[madscientist451]

Don't know for sure, but maybe Beersmith doesn't account for any additional wort from squeezing the bag. How much wort you get is going to depend on several factors, probably too many for beersmith to calculate.

 

[FunkedOut]

that's where i was on post #4

 

[robcj]

that's where i was on post #4

I don’t use Beersmith but my software (BeerAlchemy) doesn’t really account for squeezing or hanging and draining the bag either. I’ve always got a little extra liquid preboil and I can’t change the absorption setting in the software.

 

[ba-brewer]

In beersmith you can change the grain absorption for BIAB and traditional mashing differently but it one setting for all recipes.

options->advanced

 

[hottpeper13]

I believe the issue is NO SPARGE. Both methods you are talking about are full volume mash without sparge. I don't use software but Palmer's How to Brew formulas. The only thing I change is the absorption rate between squeezing or not squeezing. I get 80% brew house efficiency with either method, you are over thinking this.

 

[chickypad]

It sounds like you are changing your equipment profile but not adjusting your efficiency for that new equipment. The software doesn't tell you what your efficiency is, you need to input that. The calculations are only going to be as good as the info you put in. If you change systems/methods you'll need to measure you own efficiency on a few batches then adjust your profile to that, just like you presumably did with your original BIAB profile.