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BIAB using 2 pots....

hans

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Hi,

Just wondering if anyone can give me some guidence regarding equipment setup. I am using the BIAB method, but because of stove space I split my mash into two halves. I am using 2 x bags and two 17L pots, and splitting the grains evenly between them. I then only use one of the resulting worts for the boil (hops infusion). The other pot I just boil for 10 mins, cool and put into the fermenter. Can someone please give me some guidence as to how I can set up an equipment profile to represent my setup? As far as I can see you can adjust the volume of the wort at the start of the boil but I would assume that that volume contains ALL of the sugar from the mash. I'm trying to work out accurate IBU's from hop additions.

I hope I've explained the situation well enough..

Cheers,
Paul 
 
I use two pot BIAB but in a different manner. 

My first pot is my initial infusion containing about half the target total water volume + grain absorption.  My second pot is used for batch sparging the grains with the remaining water volume. 

I mash in all the grains in the first pot for one hour. After checking for conversion, I remove the bag, allow the runnings to flow into the first pot with a little squeezing to get most of the free water out. 

Then I put the bag into the second pot and stir several times while checking the volume and gravity of the first wort.  Then I remove the bag from the batch sparge and drain as much water as I can back into the sparge pot. 

I check volume and gravity on the sparge before combining the two, then recheck before beginning my boil.

In BeerSmith, I have this set up as a single infusion mash with batch sparge.  It comes out really accurate once you've done it a few times and figured out your process.

 
Thanks for the reply.

I follow a very similar process, excepting I mash in 2 pots as one pot doesn't hold enough. I use a third pot as my rinse (sparge) pot and then tip it's contents evenly into the two main pots. The issue I have is calculating what the bitterness will be when only using one of the main pots for the boil.

Cheers,
Paul.
 
When you're applying different techniques to different batches and blending them, accuracy becomes elusive.

BeerSmith, as with most (and probably all) brewing software thinks of brewing one beer as a linear and predictable process; aka a Recipe. By splitting grists and worts, you are effectively making two separate recipes to fill one fermenter. In professional brewing it's common to make several batches to fill one fermenter.

I would suggest that you design a "master" recipe, just as you do, now. Then create equipment profiles for each pot. The BIAB mash profile from the master recipe should apply to both batches.

Since you have uneven boil times (reflected in the different equipment profiles) BeerSmith will predict different gravities for each batch. Use the dilution tool to combine them for a correct OG. You may have to modify your master recipe boil time or boil off to reflect the correct gravity prediction.

All of this is important for accurate IBUs because they are a measure of ppm or ml/L. IBUs are also gravity dependent.

I would suggest that the second batch have a boil time of 30 minutes and be used for all hops over 50 IBUs in any recipe. This additional time will enhance hot break and remove more DMS. Using this batch for all flavor and aroma additions could enhance their properties, as well.

Or... Just get a bigger pot and burner.




 
Since you are making a recipe, in reality, twice in one session.  I would halve the recipe for your full volume and brew it as two separate recipes side-by-side to get your final desired volume.  In this way, you will preserve the ability to have Beersmith predict the final properties.
 
Hans

Stovetop brewer here as well. Instead of evenly dividing the grains and water try using BS to zero in a good ( 1.030-1.040) preboil gravity in pot 1 by varying water volume; adding the correct grains by mashing ratio. You will put ALL boiling hops in there. Write down the water going into that mash. Then put all your ingredients hops and water into BS as if it is one great brewpot.  The preboil water to be added to pot 2 will be the difference, what is left from subtracting that pot 1 volume. You are actually mashing both pots and combining after the boil so the grain ratios should work out. Probably you are adding late addition LME also. Works well for me anyway.

Also make sure your profile has the sum of mash tun weight and volume so the volume tab works correctly. For the boiloff, must input a correct figure because each pot will have a full boiloff loss according to its surface area (higher losses than if one big pot). You could calculate a loss rate using the combined surface areas or what I did was run an experiment to determine each pot'd boiloff loss and add them together.
 
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