BIAB half batch question

[Iceman6409]

Hello all,

I am interested to try BIAB. But I would like to try 2.5 gallon batches. I have a 9 gallon kettle to work with. Actually I have a 5 gallon kettle as well. So just as an example let's say my grain bill is a total of 5 lbs. So I am assuming that in BIAB we would put ALL the water in the kettle. So if I use a 1.25 ratio I should put about 1.5 gallons water for the 5lb bill. So from there with regards to water how much more would I put it to get to pre boil volume?

 

[Sudstud]

I just started doing half batch BIAB, my method-
Mash in with your total pre boil volume, in your case, 4 gallons should do it, allowing 1-2 liters for grain absorption (based on .06gallon/per pound loss if you squeeze the hell outta the grains.) and a 1 gallon boil off should leave you with ~2.5 for fermentation. They say that mashing thinner will produce better efficiency and I can't argue with it because my first batch came in at over 85%.

You could mash in at 1.25liters/pound and then sparge with the difference to get your boil volume but that seems like an unnecessary step if your pot is big enough to handle all the grain and water at once.

Hope this helps!

 

[tre9er]

Since you have the 5g pot I'd recommend mashing in it. For a 5g grain bill you're talking under 2g of water for mash. If you can get the grain and 1.6g of water in that 5g pot, mash in that. Then heat about 2g. in the larger pot to your sparge temp (probably 170's). Once your mash is done, pull the grain bag up, squeeze, and then place it in the larger pot of sparge water and leave it for 10m. Then pull it up, squeeze, and discard grains. Now just add the smaller pot of wort to the larger one and boil. Should be just over 3g preboil.

Of course I'm rough-shotting this. The actual volumes depend on your system and you'll figure those out over time.

 

[GrainWhisperer]

I did a 2.5 gallon BIAB with about 5.5 lbs of grain.
Mashed and sparged in two different pots.
Mashed in 1.5 gallons (1.25 quarts/pound of grain will be 6.25 quarts for 5 lbs of grain, so just over a gallon and a half).
Sparged in 2.5 gallons.
After water loss from grain absorption and boiling, it came out about right (fit nicely into a new 3 gallon glass carboy with enough headspace).

 

[djfriesen]

I usually estimate somewhere around 1 pt loss per pound of grain. If you don't want to sparge, just add that over and above your preboil voume and you're set. You won't get quite as much efficiency without sparging, but you'll get by.

But, since you have a second pot, there isn't really a reason not to sparge, with the possible exception of saving time. I haven't found it to be very time consuming. Heat your sparge water while your msh is going, and then dunk sparge for a while. You can add in the grain absorption water in eaither step, aiming to fall somewhere between 1.25 and 1.5 qts/lb in mash thinkness. This is exactly a scaled-down version of how I do my 5 gallon BIAB batches.