Please Help an old hand understand BIAB

[Gavin C]

I don't lose much to absorption because I squeeze. Generally I loose about 1/2 gallon for an 10-11 lb grain bill. All systems will be a little different. I find Beersmith to be spot on when it comes to volume calculations once the correct variables are entered.

A typical brew in my 10 gallon megapot (holds 11G) I think.

Approximate measures would be

7.5 gallons of strike water
10-12lbs grain
1.25g boil-off per hour on my NG stove
0.25 gallon lost to trub and plate chiller/pump tubing assembly

5.5g to FV

 

[doug293cz]

So in summary, BIAB is just like traditional three vessel brewing. The difference is you're using a bag to move the grain instead of leaving the grain and moving the wort.

Brilliant! I never thought of it that way, but it's a perfect way to describe the difference.

Brew on

 

[doug293cz]

.45 gallons per pound of grain lost to absorption

EDIT: noticed the 0.45 above was a typo compared to your previous post where you used 0.045.

Depending on how you handle bag draining, your grain absorption should be in the 0.05 to 0.125 gal/lb. 0.05 is for a very aggressive bag squeeze, and 0.125 for just a short drain. A long drain, with no squeeze, should put you in the 0.08 to 0.10 range. You'll have to make measurements with your process to get better estimates than that.

Brew on

 

[brewguyver]

I was always taught that too thin of a mash volume would hinder the conversion of starches. But obviously that's out dated wisdom. After 20+ years of being I'm finally reading some new beer books. I generally make fairly low gravity quad fable beers. So I think the pot will work fine for most of my beers.

Careful - in other styles of mashing, being too thin or thick can still be an issue. Most of this stuff around efficiency applies specifically to BIAB.

 

[doug293cz]

Careful - in other styles of mashing, being too thin or thick can still be an issue. Most of this stuff around efficiency applies specifically to BIAB.

What sort of issues?

Brew on

 

[Foosier]

I agree. I don't have efficiency issues. If I was to claim an issue it would be regularly over shooting my OG by a point or two.

I do full volume mash BIAB in my 10Gal pot outdoors. I do not sparge, I lift the bag when mashout is complete and set the bag in a bucket to continue draining. I have hit 80-85% on my last 4 brews. One of those included a triple that maxed out my pot. (overshooting that gravity made for a powerful triple!)

 

[BridgewaterBrewer]

Kai Troister (the Braukaiser) did some great experiments looking at the effects of many mash parameters (time, pH, mill gap spacing etc) on efficiency and showed that mash thickness is not critical at all.
http://braukaiser.com/documents/Effects_of_mash_parameters_on_attenuation_and_efficiency.pdf

 

[jtratcliff]

@itratcliff how do you calculate your dunk sparge water volume? standard all grain sparge volumes? 1.3qt/lb and 1.3qt/lb?. Do you get into mash thickness calculations?

I see that this is pretty much answered by others up thread but for completeness, I'll chime in...

I figure my total volume for a 6.5 gallon batch accounting for kettle losses, grain absorption and boil off, etc, then I decide the volume (grain + hot liquor) I'm comfortable mashing in my 10G kettle. Everything else goes in the sparge. I mostly do a dunk sparge because I'm a little nervous going all the way the top of my kettle trying for a no-sparge

Usually, it ends up being about 6.5-7 G of water to mash and 1.5 G to sparge in a 12-13 lb grain bill. But I'll juggle those volumes as needed to fit my available kettle sizes depending on the grain bill. I think it's usually somewhere in the 2.3 to 2.5 qt/lb range. I use brewtarget and it's mash wizard to calculate volumes and temps. There are plenty of BIAB calculators that you can use to get volumes and temps without going to a full-on brew software package.

It really is that easy.

 

[Magnus314]

Just get a true BIAB bag (I like my Wilserbrewer bag, might as well get the pulley and extras for like $10 extra or whatever) and try it.

Everything else is conjecture until you try it once and note your results!

You could have higher, or lower, mash efficiency. You might need more, or less water and have to, or not have to, pour over sparge, or a longer, or shorter, mash time.

BIAB is great. I think better (and I abandoned a many-hundreds-of-dollars-and-many-hours-of-labor 3 vessel system to go BIAB the first time).

None of the variables are for sure, until you know what you need to adjust for. Then, it's easy!

 

[lazarwolf]

Well I appreciate all the help. Like I said not new to brewing, but Just haven't tried the biab thing before. I do occasionally like to do an all grain batch. But my thinking has always been that BIAB should probably result in higher efficiency not lower, you have all confirmed my suspicions. Like all brewing it is really about the skill set, fresh ingredients, and attention to detail of the brewer, and not really just about which process you are using.

 

[brewguyver]

What sort of issues?



Brew on

I brewed on new equipment last weekend, ended up cutting grain bill and mashed around 2.5 qt/lb in my tun. So mash was too thin and water too hot (comedy of errors) - I got a whopping 40% efficiency. Crush is the same as usual.

Has nothing to do with BIAB tho.

I spent the money and got my lhbs's biggest grain bag - fits a 9 gallon pot. I don't mess with non food grade stuff, even if it's just marketing dif betw paint strainer bags and other options.

 

[doug293cz]

I brewed on new equipment last weekend, ended up cutting grain bill and mashed around 2.5 qt/lb in my tun. So mash was too thin and water too hot (comedy of errors) - I got a whopping 40% efficiency. Crush is the same as usual.

Has nothing to do with BIAB tho.

I spent the money and got my lhbs's biggest grain bag - fits a 9 gallon pot. I don't mess with non food grade stuff, even if it's just marketing dif betw paint strainer bags and other options.

Given the over temp mash, the low efficiency cannot be attributed to a thin mash.

Brew on

 

[gbx]

I started BIABing 4 years ago. I had done a few partial mashes and all grain using a mash tun I bought at the LHBS. After 1 attempt at BIAB I gave up mash tuns entirely and have done 80+ batches since.

And efficiency. STOP CARING ABOUT IT. unless your efficiency is wildly unpredictable don't worry if its 90% or if its 50%. Grain is cheap! you will spend way more money on propane and hops and yeast than you will on the few extra lbs needed to compensate for a crappy 50%. And how much is your time worth? You are going to spend minimum of 5 hours labour on a 5gal batch of homebrew and you are concerned with a little bit of grain? If you are a commercial brewery, sure but I've talked to people who won't try BIAB because they might get a lower efficiency and then later you find out their burner eats through a tank of propane every 2.5 batches. Thats something you should be concerned about as it costs way more and much bigger hassle to refill your tanks than it is to grind a couple of extra pounds.