BIAB Sparge Water Question

[putridbiscuit68]

Hi everyone,

So I've been brewing 5 gal extract batches for a bit now, and want to get in to the BIAB method. I have a 7.5 gal kettle which I know isn't large enough for full volume 5 gal boils, but would I be able to mash in maybe 3.5 gallons, and then sparge two gallons of hot water and still hit my OG? Would using this method dilute the wort too much? Do I just need to get a bigger kettle?

Thanks

 

[broadbill]

sounds like it would work.

 

[friarsmith]

I imagine you'd max out the 7.5g kettle during the mash if you used the full pre-boil volume of water plus grains. To your original question, mashing with 3.5 gallons then running a few extra gallons of sparge water over the grain bag to reach the full pre-boil gravity should work. You can always scoop up wort and re-run it through the bag until the pre-boil gravity reaches your target.

Before upgrading, I brewed full wort boil 5 gallon batches for years with an old 7.5 gal pot. But be careful the first 20 minutes of the boil.

Here's an idea: After reaching your full 6-7 gallon pre-wort volume and desired pre-boil gravity, remove and save a gallon or so of wort before starting the boil. After 20 minutes or so of boiling, gradually add the saved wort back in over ~10 mins.

 

[putridbiscuit68]

Thanks. Which calculator could I use that can account for sparge water? Do I just set my batch size as 3.5 gal? If I try to enter my batch size as 5 gal in biabcalculator.com it says my total mash volume is larger then the kettle capacity.

 

[broadbill]

Thanks. Which calculator could I use that can account for sparge water? Do I just set my batch size as 3.5 gal? If I try to enter my batch size as 5 gal in biabcalculator.com it says my total mash volume is larger then the kettle capacity.

Just take the total water needed from the calculator, and pull out a couple of gallons for sparge and mash with the difference.

 

[doug293cz]

Thanks. Which calculator could I use that can account for sparge water? Do I just set my batch size as 3.5 gal? If I try to enter my batch size as 5 gal in biabcalculator.com it says my total mash volume is larger then the kettle capacity.

Use the BIAB calculator from @pricelessbrewing . It has the ability to do calculations with or without sparging. You might want to consider doing a dunk/batch sparge in a bucket instead of a pour over sparge. It's relatively easy to predict the outcome of a batch sparge, but the variability inherent in a pour over sparge makes accurate prediction impossible. However, both will make fine beer, so method is a mater of personal preference (and how much you want to geek out on predicting and hitting your numbers.)

Brew on

 

[doug293cz]

...

You can always scoop up wort and re-run it through the bag until the pre-boil gravity reaches your target.

...

Rerunning wort thru the grain will not increase the SG. And, if you have done a sparge, rerunning the combined wort back thru the grain will actually reduce the SG a little. I can show you the math if you want, but it can be a bit hard to follow (especially if you don't like math.)

Brew on

 

[griz_brew]

That's pretty much what I do. I can mash up to 14# grain in 5 gal in that size pot. Then 1-2 gal pour over sparge depending on absorption. Just watch out for boil overs.
I will boil for 60-90 min depending on the recipe, then I usually need to add top up water to get back down to target OG.