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Maximum Brew-in-a-bag effeciency

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bakins

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After seeing various discussions on BIAB, I decided to attempt to calculate the maximum efficiency possible for BIAB ( brew in a bag).

I used the info I gained from http://braukaiser.com/wiki/index.php?title=Troubleshooting_Brewhouse_Efficiency

I had a conversation with Kai and he said my numbers looked reasonable. Any errors, however, are my fault, not his.

All water measurements are at room temperature. (If not you have to account for expansion).

Lets assume a basic 10 lb grain bill and that the grain has an 80% extract potential (pretty normal). Assume we mash in with 8 gallons of water. Now the math is much more straight forward with metric numbers, so I'll convert.

10lb = 4.5 kg
8 gallons = 30.24 L

Our maximum pre-boil gravity, since we are not sparging, assuming 100% conversion efficiency (which is doable):

4.5 * 0.8 * 100 / (4.5 * 0.8 + 30.24) = 10.64 Plato or about 1.043 SG

Assuming, the "normal" grain absorption of .125 gallons/pound (1.05 L/kg), we should collect 6.75 gallons (25.5 L).

So, our efficiency "into the kettle" is:

100 * 25.5 * 1.043 * (10.64/100) / (4.5 * 0.8) = 78%

(Note: depending on how you round, the numbers fluctuates. I did this in a spread sheet and didn't copy all the decimals to this post).

One of the claims of BIAB is lower grain absorption rate (because the bag can "squeeze" a little more wort from the grain). So, just lowering it to .1 gallon/pound, we should collect 7 gallons (26.5L). So our efficiency would be:

100 * 26.5 * 1.043 * (10.64/100) / (4.5 * 0.8) = 81%


I'm sure this is full of errors, but wanted to get a discussion going. Please correct me. I just know that I don't get the horrible efficiencies that people say I should when I BIAB.
 

DeathBrewer

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Why would you get horrible efficiency with BIAB? I usually get around 70-75%...not the best in the world, but I'm also not going nuts with my sparge. If I take my time and do a proper sparge, I can easily get 75-80%. Sometimes I really half-ass and get 65% or so, but that's only when it's planned.
 

Chips

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I think if you're using a BIAB similar to this method there should be no sparge. A mashout however will greatly increase efficiency! I usually am able to get 75+% using only one pot and a bag (and some heat). Just make sure that your bag is not touching the bottom of the pot when the flame is on, or hanging over the edge for that matter.
 

Bobby_M

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Yeah, the assumption is no sparge. It's not like you can't do a dunk-sparge in a secondary vessel and it has the advantage of not requiring that large of a kettle because the two worts are combined after you remove the grain bag.
 
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bakins

bakins

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Yes, I'm referring to the "Aussie" Brew-in-a-bag method - no-sparge.

I just keep seeing on boards (this one included) about how you can never get above x% (where x is usually 60 or so) using no-sparge BIAB. I generally get 78%, pretty much like clockwork when I BIAB *.

And, theoretically at least, a mash-out is not needed. However, I do generally do one.

*on my last BIAB, i got 83%. I actually rechecked my numbers because that sounded high. It's possible looking at the math. I've started doughing in at 135, raise to 150, then 158, then 170 using my RIMS. the 135 helps with doughballs, probably not needed, but it's no trouble.
 

Bobby_M

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That's certainly the math under ideal situations. You have to have a fine crush and convert every bit of starch. After that, it's easy because there's absolutely no dead space.
 
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bakins

bakins

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That's certainly the math under ideal situations. You have to have a fine crush and convert every bit of starch. After that, it's easy because there's absolutely no dead space.
Yeah, when I BIAB, I crush really fine. I always adjust for ph whether I'm BIAB or "normal."

According to Kaiser, 100% conversion should be attainable with a little care. 95%+ is pretty much what you can get with a decent crush and pH in the right neighborhood.

I'm still working on BIAB rig plans in my head:
- incorporate a winch to lift the bag
-single vessel
- Just use an element directly in the kettle and recirculate, rather than an external RIMS. Sorta like many of the direct fired MLT's I've seen.
- Maybe even use a steamer basket for the grains lined with SS mesh. It may not get the same "squeeze" affect (effect?), but never have to worry about it ripping. Still easy to clean (just spray it off).
 

Chips

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I think 75% is pretty easily achievable if you use a fine crush and do a mashout. 83% sounds totally feasible (and awesome!).

You mention that you have a BIAB RIMS system. Very interesting...do you have any pics or a little more info on this? I can't brew outside in the winter here so I'm looking for some alternatives!
 

alcibiades

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I got 82% efficiency lastnight with BIAB. +1 on finding some type of winch to hold up the bag and let drip, my arms are usually pretty tired after holding a full bag of wet grain. A technique ive been recently using is to sparge in a seperate vessel, then do an extra sparge by holding the bag above the wort while a friend slowly pours a half gallon of 170 F water all over the bag....seems to work for me.
 
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bakins

bakins

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You mention that you have a BIAB RIMS system. Very interesting...do you have any pics or a little more info on this?
I have a typical 3 tier system that I sometimes BIAB. Need to get some more pics..
 
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bakins

bakins

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I A technique ive been recently using is to sparge in a seperate vessel, then do an extra sparge by holding the bag above the wort while a friend slowly pours a half gallon of 170 F water all over the bag....seems to work for me.
Yeah I've seen and did that before. I'm thinking with a winch, I can just lift and let it drain as I bring wort to a boil - one less pot to clean.
 

rico567

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I'm thinking a winch is a must. I've got the garage roof trusses up there about 10 feet off the floor. Not sure how much they'll handle- but I know how to find out.
 
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bakins

bakins

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Any ideas on a winch design? I'm thinking huge tripod...
I'm thinking of basically building gallows over my stand. Since I'm all electric, my stand will be wooden. I'll just use some 2x4's (or 2x6's) to put a "beam" over my pot and use a pulley with a trailer winch like this:

 

Cheaton

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Yeah I've seen and did that before. I'm thinking with a winch, I can just lift and let it drain as I bring wort to a boil - one less pot to clean.

Why not just fashion some sort of bracket to hold a colander over your kettle. Pull bag out with one hand, pop the colander on with the other, plop bag in colander. Maybe a round charcoal grill top (new of course) and just skip the colander all together, allthough the bowl shape of a colander would hold it nicely in place. You can even give it a sparging rinse since its just sitting there..... Winches and pullies may be fun, but if you're doing this indoors on a stovetop......
 
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bakins

bakins

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You can even give it a sparging rinse since its just sitting there..... Winches and pullies may be fun, but if you're doing this indoors on a stovetop......
Okay, so everyone can see: I'm talking about Aussie style BIAB: no-sparge If you talk about sparging, we are not talking about the same thing. Can you get better efficiency with sparging, maybe. Is that relevant to this conversation, not really. I'm discussing maximum efficiency for no-sparge brew-in-bag - a ll the brew water in one vessel with the grain. (not personally aimed at you Cheaton...)

And, I already have a dedicated brew rig. I'm thinking of making a new one made especially for BIAB.

Currently, I just throw the bag into a bucket with a vegetable steamer in the bottom of it and a few minutes later pour that liquid into the boil kettle. But, I still have to hold the bag suspended for quite a bit before I can do that or I'll have a huge mess. With a winch, I can leave it suspended and not worry about getting burned or my arms getting tired.
 

Chips

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Instead of a winch you could sew (or get someone else who knows how to sew as I did) an elastic band around the top of the bag. Then just stretch it around the edge of the pot! This seems to work just fine for me; no hot steam burning my arms as the bag stays firmly in place! Might be easier/cheaper than a winch.
 

Cheaton

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Okay, so everyone can see: I'm talking about Aussie style BIAB: no-sparge If you talk about sparging, we are not talking about the same thing. Can you get better efficiency with sparging, maybe. Is that relevant to this conversation, not really. I'm discussing maximum efficiency for no-sparge brew-in-bag - a ll the brew water in one vessel with the grain. (not personally aimed at you Cheaton...)

And, I already have a dedicated brew rig. I'm thinking of making a new one made especially for BIAB.

Currently, I just throw the bag into a bucket with a vegetable steamer in the bottom of it and a few minutes later pour that liquid into the boil kettle. But, I still have to hold the bag suspended for quite a bit before I can do that or I'll have a huge mess. With a winch, I can leave it suspended and not worry about getting burned or my arms getting tired.
I gotcha, but really I wasn't commenting on sparging or setting up for a sparge. I was presenting a way to do your method without a winch on an indoor stove top without having to hold the bag for draining. You may even be able to find a commercial colander big enough to fit the top opening of your kettle without making a bracket. I simply mentioned that if you DID want to give it a rinse you could without much trouble. I don't think for most men that lifting 20lbs (10-12 lbs of grain + water) straight up with one hand long enough to slide somethign under it would be much of a problem.
 
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bakins

bakins

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Instead of a winch you could sew (or get someone else who knows how to sew as I did) an elastic band around the top of the bag. Then just stretch it around the edge of the pot! This seems to work just fine for me; no hot steam burning my arms as the bag stays firmly in place! Might be easier/cheaper than a winch.
I'm talking about when you are removing/draining the bag. But I do like the elastic for when it is in the kettle.
 
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bakins

bakins

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I don't think for most men that lifting 20lbs (10-12 lbs of grain + water) straight up with one hand long enough to slide somethign under it would be much of a problem.
When it's 170 degrees, it gets interesting after a couple of minutes the way I do it now:)

But yeah, I see your point. Not a bad idea if there are colanders the right size. Good idea.
 

ahansler

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I have gotten 85% efficiency using BIAB. Smaller beers get better efficiency, my milds and bitters average in the 80's. As gravity goes up my efficiency goes down.

For draining, I have a pulley mounted to my ceiling with a rope run through it that I tie around the bag. Lift it up and tie it off on a cleat on the wall.
 

Cheaton

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Well, the Tim Allen in us always wants to add that extra gadget. Pullies and ropes are fun after all, and if brew day gets too frustrating you can always hang yourself with it! :cross:
 
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bakins

bakins

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Good point, you really don't need the mechanical advantage of a winch.
When did that ever stop us? :)

I was really thinking about a winch bcs, a) they're pretty cheap b) has a built-in stop c) come on, it's a winch on a brew cart...


I was thinking something like this, but with a winch:

 
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bakins

bakins

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This is what I'd been thinking about:


Could lift it out, sit it on a grill on top of kettle and let it drain. I'd actually have my "bag" in it inside the kettle. Thought about even using SS mesh inside it.

But gallows and a winch would just bee too cool ;)
 

Cheaton

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Well, as hot as that handle would be you'd definitely need to haul it out with something.
 
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bakins

bakins

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Well, as hot as that handle would be you'd definitely need to haul it out with something.
A winch! ;)

For my turkey fryer that I actually use for food, it has a triangle thing that you use.
 

weirdboy

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What I do if I'm doing BIAB outside is position the BK on the ground, at the edge of a table, and pull it out by hand then clamp it to the edge of the table, suspended above the BK, to let it drain.
 

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2 comments,

1. I use my aluminum folding ladder. I open it up to one of the top steps is above my kettle, then loop the bag tie over the step, pull it up, and tie it off on a lower step. Not pretty but it works.

2. I keep trying to get my wench to do my heavy lifting on brew day, but she does not see the humor in a statement like that...
 

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This is my 47th brew. My 2nd BIAB experience.
Just thought I'd chime in here since I took pretty good notes.

My grain bill was 493.3 pp.
Preboil gravity was 1.053 (@60F).
Lauter volume was 7.25g @ 212F = 6.92G @ 60F
Pre boil potential points: 368.88
Lauter Efficiency: 368.88 / 493.3 = 74.78%

My actual grain absorption-
13.27 lbs grain absorbed 1.04 gal (@60F) = 0.078 gal/lb = 0.313 qt/lb

Mash volume increase contributed by grain:
1.25 gallon (@60F) / 13.27lb = 0.0941 gal/lb = 0.376788 qt/lb

PS-
I don't know what my LHBS's grain mill is set for, but I ran it thru twice, trying to achieve more of a "fine grind".

I have an eye hook embedded in my garage frame and a rope cleat next to that for suspending the bag over the kettle. I let it drain until I reach boil. Then I take measurements and start my boil timer.
 
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