2.5 gallon BIAB

[Beer-lord]

I've seen lots of calculators for BIAB water amounts but is it the same when you only do 2.5 gallons?
I've got 6.25 lbs of grain and using the most popular calculators, it shows, for a 60 minute boil, 4.28 gallons. Based on just my 5 gallon BIAB boils, that seems like about 1/2 to 3/4 of a gallon too much.
Would I be better using less and then sparging just a bit to bring up what I need or just do the 4.28 gallons then ditch whatever can't fit in my 3 gallon fermenter?
I'm not use to small BIAB batches and have a few I'm experimenting with. Beersmith is totally off but I think my input is wrong so I'm hoping others that do wussy size batches like this can tell me.
Thanks

 

[Malticulous]

When I do them I don't sparge. I'll mash as thin as 4 qt/lb. The mash ratio is in direct proportion to the pre-boil gravity. The only calculation I need is what Kaiser calls conversion efficiency. That gives me my pre-boil gravity. Grain absorption is so small sparging dosen't increase efficiency much anyway.

 

[Beer-lord]

I normally don't sparge for a BIAB but if I need to make up some water, I'll do it.
But isn't the point of BIAB to try not to add any water after the mash?

 

[Malticulous]

I normally don't sparge for a BIAB but if I need to make up some water, I'll do it.
But isn't the point of BIAB to try not to add any water after the mash?

Yeah. There is a thread somewhere at aussiehomebrewer.com where it was invented. The idea was brewing all grain in a single vessel.
This might be it. http://www.aussiehomebrewer.com/forum/index.php?showtopic=11074

 

[LLBeanJ]

4.28 gal seems about right to me. You'll lose about a 1/2 gal to grain absorbtion and another 1.25 gal from boil off, and that'll put you right about 2.5 gal going into the FV.

 

[DewGun316]

I've seen lots of calculators for BIAB water amounts but is it the same when you only do 2.5 gallons?
I've got 6.25 lbs of grain and using the most popular calculators, it shows, for a 60 minute boil, 4.28 gallons. Based on just my 5 gallon BIAB boils, that seems like about 1/2 to 3/4 of a gallon too much.
Would I be better using less and then sparging just a bit to bring up what I need or just do the 4.28 gallons then ditch whatever can't fit in my 3 gallon fermenter?
I'm not use to small BIAB batches and have a few I'm experimenting with. Beersmith is totally off but I think my input is wrong so I'm hoping others that do wussy size batches like this can tell me.
Thanks

I'm in the same boat, I have a thread in this section with awsome input. I plan doing small batch full boils. My only problem is figuring the proper amount of fermentables to use for those batches. A video in my thread shows the northern brewer folk doing a 3g batch, in a 8g pot with 5g full vol.

Here is the link maybe you can see something useful
https://www.homebrewtalk.com/f36/biab-notes-320534/index4.html

 

[smyrnaquince]

4.28 gal seems about right to me. You'll lose about a 1/2 gal to grain absorbtion and another 1.25 gal from boil off, and that'll put you right about 2.5 gal going into the FV.

+1

Agree on the 4.28 gal being about right. Exact numbers will depend on target OG and your extraction efficiency (Efficiency into Kettle).

Best site for BIAB is http://www.biabrewer.info

 

[Beer-lord]

Thanks for the input guys. Will proceed as discussed......and make notes for the next time so I don't have to bug folks again.
Stone IPA on the way.