Maxi BIAB

ceejam · Nov 9, 2018

So, having done 11L BIAB stovetop brews now, I’m wondering what the limits of my kit would be.

I’ve got a 15L pot which I can boil in on my kitchen induction hob.

I’ve ended up with 12L of 1040 wort using 2.2kg of grain, so I think there’s a bit of capacity to brew bigger volumes.

Last brew had 2.1kg of grain and 6L of strike water. Can I reasonably double the grain without doubling the mash liquor?

I also have a cool box which I used last brew for a dunk sparge, as my fermenters are all in use. Cool boxes don’t pour very well - I can see why people fit taps! :laugh8:

What’s the pros/cons of adding more grain to a similar volume of liquid? Guessing a drop in efficiency?
What’s the commonly used grist/liquor ratios?

I’m going to try by experiment - double the grain and add what seems reasonable for mash liquor.

By using cold water to dilute, this would also speed up cooling, as I currently chill the pot int the sink with the cold water tap on low.

-Bezza- · Nov 9, 2018

I'm no expert but would think you should be able to get 20l of beer at around 5% from a 15l pot. This is loosely based on advice I was given a few months back, although someone might be able to be a bit more accurate with water volumes (or use Brewers Friend to help).

Use the pot to heat 15l of water to mashing temperature.
Mash in a 30l fermentation bucket wrapped in a blanket/sleeping bag.
5kg grain will give you a water to grist ratio of around 2.5x
Whilst mashing, heat another 5l of water (or so)
Once mash completed, squeeze grain bag into the fermentation bucket and dunk sparge. Squeeze the bag again and chuck the grain.
Transfer the wort from the fermentation bucket into the pot. You probably want around 12l in there to start with.
As you boil, wort will evaporate. Keep topping up with any wort left in the fermentation bucket.
Once the boil has completed, you'll have a fairly strong wort.
Transfer to the fermenter and water down to about 20l (or until you get your target SG)

I don't think you'll have a discernible drop in efficiency. The performance of the hops will change in a more concentrated wort though, so if you're looking to follow a recipe, I'd plug it into a recipe builder and adjust the hops to make sure you get the right IBU.

ceejam · Nov 9, 2018

Cheers for that - sounds like what I was thinking!

IainM · Nov 9, 2018

Sure, I've done 12L of RIS at 1.102 in a 15L pot, mashing the 5.5kg grain bill in a well insulated fv-sized bucket, which would have diluted down to 1.050 at 25L. If I remember well, I ended up with a bit more wort than I could fit in the pan so used a casserole to boil down the extra couple of litres or so.

cushyno · Nov 9, 2018

If you use a large fine mesh BIAB bag in the coolbox, one that is large enough to allow grain to touch all sides right into the corners, you can drop the end of a syphon tube (with tap) into the bottom before putting the bag in, then mash in the bag-in-coolbox. Tilt the coolbox only to a small degree and you should be able to syphon out the wort into a spare FV as you ladle in water from stockpot for the sparge.

This means you've gone from Maxi-BIAB to 3 vessel system using kit you already have.

ceejam · Nov 9, 2018

cushyno said:
If you use a large fine mesh BIAB bag in the coolbox, one that is large enough to allow grain to touch all sides right into the corners, you can drop the end of a syphon tube (with tap) into the bottom before putting the bag in, then mash in the bag-in-coolbox. Tilt the coolbox only to a small degree and you should be able to syphon out the wort into a spare FV as you ladle in water from stockpot for the sparge.

This means you've gone from Maxi-BIAB to 3 vessel system using kit you already have.

That was my plan - but the round bag didn’t fit the rectangular cool box very well - I think some bulldog clips might be required!

braziliain · Nov 9, 2018

I brew a full corny using my stove top pan. 13L of concentrated wort in the kettle that I then back liquor in the fermenter with 6L of cold water to dilute to the target OG. Works a charm. As you say, it helps to cool, so typically I finish chilling at 28C and bang in 6L of 5C water to get to pitching temp.