Grain Bill on High ABV with BIAB

[sleev-les]

Wasn't sure on how to even search this, but my future plans started me thinking..

Since grain bill plays into gravity and your overall ABV at the end of a brew, using BIAB what would happen if your grain bill is so large that there is more wort after the mash than you need for boil volume. For example:

1. Brewing 5 gallon batch in a 20 gallon vessel
2. Grain bill is 18 pounds
3. At a rate of 2 quart per pounds (36q), you need 9 gallons of water for the mash
4. Even with grain retention (say 1 gallon as a place holder) you end up with 8 gallons of wort.
5. Only need roughly 6.8 to boil

Since you are above boil volume do you just get rid of the extra wort down to the needed volume of say 6.8 gallons, then boil, cool transfer? Can't even sparge some of the grain since you're already over.

In my OCD mind, I feel like I'm missing something or have something wrong. To date, I've never had a grain bill that required more than boil volume and still sparge my basket to get to boil volume. In the future I was looking at something like what Spike is about to release, but was curious how high ABV beers work in a BIAB system. Am I thinking this correctly or am I way of on my though process.

 

[mirthfuldragon]

http://www.biabcalculator.com/ is what I use. It has proven accurate with my system. It calls for 7.94g of strike water in your situation. BIAB uses different formulas. You might lose some efficiency as the OG increases, but you can sparge and boil off or just add more grain - and that lose is going to depend on how fine your crush is and how much you squeeze your bag/grain absorption. I use 0.035 for my absorption rate, but I also squeeze the bag pretty well. YMMV.

 

[Oldskewl]

I agree. I use biabcalculator.com as well. You need to figure out your system as to grain absorption and trub varies depending on the recipe. But it will get you darn close. You do not need 2 qts of water per pound of grain.

 

[sleev-les]

I agree. I use biabcalculator.com as well. You need to figure out your system as to grain absorption and trub varies depending on the recipe. But it will get you darn close. You do not need 2 qts of water per pound of grain.

That's good to know. I just always went on the mash thickness calcs and not taking into account BIAB. Didn't even know it was a thing. I'm using a Grainfather and dialed in the grain absorption and trub/deadspace losses. Last brew was spot on so I was happy that I finally got it tweaked. This question came to mind when I started following the upcoming Spike system and with the ability to do 5 or 10 gallon in their 20 gallon vessel I was curious as to how the water volume worked out. You guys def helped me out. I appreciate it.