# Double Batch Biab In 50l Pot ?



## Bada Bing Brewery (6/11/11)

Guys. I've only ever done single batches in my 50L pot. I basically brew a corney at a time. Never tried a double. Need some advice. Usual strike water is about 32L. Is it possible to do a double in a 50L pot? It is a simple Galaxy smash ale with a grain bill of 4.2kg of grain for 21L batch - OG of about 1050.
Thoughts and advice appreciated......
Cheers
BBB


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## manticle (6/11/11)

I can't answer for BIAB but purely in terms of a boil, you'd be struggling to do a double batch. I use a 50L keggle and the most I've ever boiled in it is about 42L. That was on the brink of boilover. I lose around 10 L to evaporation (you may lose less) so maybe a batch and a half.

Pretty sure RDeJvun (can never get the userbame acronym right) and Nick JD among others have done higher gravity smaller BIABS and diluted back later - just need to calculate your hopping rates accordingly and efficiency may be a bit down.


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## Dazza88 (6/11/11)

Without doing a double batch in a big pot (waiting for bulkhead for my new 70 L pot), how about a slightly high gravity batch like many do in a 19 L pot. 

It might be you use say 44L initial volume and it boils down to under your target end of boil volume then adjust with water into the fermenter. 

I would guess the following could be issues. 

1. would evaporation be as extensive in a higher volume with the same heating device, prob less. 

2. would eff be less due to higher mash to water ratio, don't know.


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## argon (6/11/11)

Yep double batch BIAB can be done in a 50L pot. I've done maybe a dozen double batch BIABs. It's best to be done by adding top up water to the fermenter. 

You do hit a bit of a ceiling as to how big you can make your beers for a double batch. I found that as the grain bill become larger (say over 9kg) efficiency drops off pretty sharpish once you have a grain bill over 9kg. At 70% you can still make 2 kegs of 1050ish beer with that so it's not too bad.

For double BIABs, to get a reasonable efficiency you'll need to do a bit of sparging. I used an esky. Anything that's big enough to take your grain bag and enough water for the grain to rinse in is fine.

Here's what i used to do;
- Add 50L to the keggle and bring to 85C, 
- Drain off 20L into my 44L esky, (eskys are good cause you need to hold the water at that temp till the mash is finished)
- Top up/adjust the keggle water to hit mash in temps, say 70C. (bit of cold water will get it right)
- Add grain then mash for 60 mins
- direct fire to hit mash out temp of 76C while stirring and sit for 10 mins
- I then pull the bag out (9kg is about as much as I can pull out of the keggle without too much hassle) dump it into the esky full of now 80C water for a dunk sparge. 
- Give it a stir, leave for a bout 5-10 mins. 
- Suspend the bag over the esky (by hand is ok... never found a skyhook very useful)
- Squeeze it till it pretty much stops dripping (no need to go overboard, just to stop dripping)
- dump the bag wherever
- Drain the contents of esky back into the keggle to hit approx 42L. It's touch and go for a little while, at this volume, just watch for boil overs
- then do your hop additions as per usual

If you're over your preboil volume, just boil off till you hit your desired mark. 
Pretty easy really. The extra bit of faffing about is worth it, when you get to fill 2 kegs. 

Employing this method I easily extract 34L to fill the 2 ex Fresh Wort Kit cubes (any cubes are fine as long as you squeeze the air out) This leaves behind about 2-3 litres of trub. I also calculate a top-up of 4 litres each to get 21L into the fermenter, gives me a pretty much spot on 19L into the keg, after polyclar and filtering.

Good luck with it... nothing like 2 kegs from on brewday
:icon_cheers:


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## ekul (6/11/11)

If you're bottling you could do a 35L batch pretty comfortably. Its not a double but if you're bottling and have the fermenting room your not limited to having to brew in 20L amounts.


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## Bada Bing Brewery (6/11/11)

Thanks Manticle, Dazdog and Argon .....
Argon - Superb.
Cheers
BBB


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## stux (6/11/11)

Bada Bing Brewery said:


> Thanks Manticle, Dazdog and Argon .....
> Argon - Superb.
> Cheers
> BBB



I aim to fill two 17L cubes. Any more than that and your efficiency plummets.

Fill your mash to the brim, top up before the boil, top up during the boil, and top up in the fermenter 

75% efficiency more than possible


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## RdeVjun (6/11/11)

As per the other guys, yeah, should be pretty easy. Scale up the BIABrewer MaxiBIAB or AHB 20L Stovetop.
Thinking of heading down that route myself, reckon I've done enough single MaxiBIABs over my last two years apprenticeship so its time to spread the wings a little and make my all too infrequent brewdays more productive! B)


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## beerdrinkingbob (6/11/11)

argon said:


> Yep double batch BIAB can be done in a 50L pot. I've done maybe a dozen double batch BIABs. It's best to be done by adding top up water to the fermenter.
> 
> You do hit a bit of a ceiling as to how big you can make your beers for a double batch. I found that as the grain bill become larger (say over 9kg) efficiency drops off pretty sharpish once you have a grain bill over 9kg. At 70% you can still make 2 kegs of 1050ish beer with that so it's not too bad.
> 
> ...



Hey Argon,

What sort of efficiency are you getting with this method?, with 20l it should give it a good rinse.

Cheers BDB


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## argon (6/11/11)

I no longer do it but 75% was common. 

As an example I did a double batch 3V last night and it had a 20L sparge.... So same same


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## marksfish (6/11/11)

to prevent boil overs just use foam control.


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