44L BIAB batch in a 40L urn

[captaincleanoff]

With time constraints, I need to push out bigger batches.

Tomorrow I'll be attempting a 44L batch using BIAB in a 40L crown urn.

I'd just like to outline the plan, and if the experts here could have a quick look over it, and point out any potential issues, I'd be very appreciative.

Plan is:

- 11kg grain bill
- 57L total water
- 5.5L loss to grain
- 5.75 boil off over 90 mins
- 2L trub
- leaves 43.75 into fermenter


- Mash with 28L water (+11kg grain, will fill the Urn). Will loose 5.5L to grain
- Dunk sparge in a bucket with 17L, then add to urn. This should almost fill it for the boil.
- 5.75 boil off
- At the end of the boil I would have used 45L of water, with 33.75 left in kettle (28L+17L-5.5L-5.75L ).
- Will then add 12L of boiled water into the kettle as it empties through my plate chiller

So should end up with 33.75L (in kettle) + 12L - 2L trub = 43.75L

Does this look alright?!

 

[Matplat]

My main concern would be filling a 40l urn with 39.5l of liquor, then trying to boil it. You're gonna have a boil over for sure.

Also, if you're adding water as it's draining, you may end up disturbing your trub cone, but that is less of an issue.

If you're not sure of the numbers, enter it into brewmate.

 

[Stouter]

I read the title of the thread, and I think no this should not happen. Have some respect for your urn man.

You can't make a beautiful clay statue out of a pile of shit clumped together at the last minute. Likewise you need to allow yourself the time to beautifully craft a decent beer in two completely separate batches.
Just don't do it to yourself, please.

 

[captaincleanoff]

why? This in theory should be no issue?

 

[RdeVjun]

You could dilute with plain water in the fermenter if the water is sanitary, a fair bit of of energy seems wasted with your proposed method. Apart from that, without scrutinising your numbers in any great depth it doesn't present any obvious hassles to me, seems quite similar to Maxi-BIAB.

 

[mofox1]

Over gravity brewing is a great way to knock out the bigger batches. Using software (brewmate) I'll make up the recipe for say 67L. When I'm brewing I'll target a preboil kettle volume of 56L to get 3 x 22L cubes worth of wort into 3 x 16L cubes. Then just dilute with 6L clean water when you tip the cube into the fermenter.

There aren't too many many draw backs as long as you have sufficient mash volume, but you will need to drop your efficiency down 5 or 10% to account for a lower mash efficiency and throw in a few extra IBU's to counter the reduced hop utilisation. It's really only a few extra $ in the batch.

One caveat... Mine is a 3v rig... Losses would probably be higher for biab. Also I think your grain absorption should be closer to 1L per kg of grain (how long do you hang the bag for?!!).

Seconding matplat... Never fill your boil vessel to capacity! And if you are going to be within 5cm or so then use an anti foaming agent!!!!

 

[Bribie G]

I faced a similar problem as I have a very handy 60L fermenter that screams out for double (40L in my case) batches.

I've struggled to do more or less your proposed method without massive dicking around with efficiencies, sparges etc.

My ideal solution was to buy a 20L Crownie I found on Gumtree and I now easily crank out double batches by teaming it up next to my 40L Crownie. I formulate a 40L recipe with Brewmate then split it between a Major (25L) and Minor (15L) brew that I do simultaneously and which adds maybe half an hour to the brew day what with the extra cleaning etc.

I'd encourage you to look for a smaller "sibling" urn that's always handy for other uses. Also the Crownie 20L has the same kick arse 2.4KW heater as the big brother, and is great for rapidly heating strike water if nothing else.

For a couple of hundred new, or buy second hand, it will pay for itself rapidly when doing 40L brews. I love mine as a standalone for doing test brews and 12.5L (fill one box of PETs) comp brews.

edit: as you said it's going to be an ongoing exercise for you, a bit of cash up front will more than pay for extra ongoing complications down the track.