BIAB: One Pot or Two?

So, I'm making the transition to AG brewing and looking to do 2.5-3 gal batches. I have two "large" pots: a 8 qt (small really), and a 24 qt. I'm planning on BIAB.

I notice that there are two methods typically employed:

1) The one-pot method, where the mash is done in the full-boil volume, step infusion, essentially no sparging.

2) What I'll cal the DeathBrewer method, highlighted here, where two pots are used--a mash pot and a dunk-sparge one.

Well, the 8qt pot is just barely enough for the grain bills I'm looking at (5-6 pounds) at a thick mash (thanks to Green Bay Rackers' calculator). I'm going to be brewing ales almost exclusively for the time being, so I don't think a thick mash (approximately 1 qt: 1 #) is harmful. So, I can just barely do the two pot method.

Is that right? will that thick mash be suitable for (pale) ales? Should I use the one-pot method without a separate sparge?

I have a colander that just fits across the 24qt pot, so I could mash the grains in the 24qt, heat the sparge water in the 8 qt and a separate tea kettle (to get 10-12 qts, right?) and pour those over the bag in the colander.

Am I over-complicating this all? What methods are y'all using? What's the best for the conditions I have now? I know ideal is for a bigger brew pot, but the ideal is not in the foreseeable future.

You should be OK using either method. However, I would recommend the two pot method due to efficiency concerns with your water-grist ratio. Since you are likely having the LHBS crush your grain, you won't be getting the most out of your grain.

The next thing to do is use the following calculator to make sure that the amount of grain and water will fit in your pots:

http://www.krotchrott.com/calc.html

Haputanlas said:

The next thing to do is use the following calculator to make sure that the amount of grain and water will fit in your pots:

http://www.krotchrott.com/calc.html

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I forgot to mention that the calculator you want is the third calculator down "Can I mash it?"

Haputanlas said:

I forgot to mention that the calculator you want is the third calculator down "Can I mash it?"

Click to expand...

I have used that calculator. For the bigger of the two project first brews, I've a 5.66lbs grain bill, which looks to fit the 2gal pot at a 1qt:1lb ratio. I know that's not the ideal ratio for mashing, but searching around on here suggests many brewers are using it.

Am I right that the concern about too much unfermentable sugar is more a lager concern than one for ales?

It's the same for ales as it is for lagers. If you have too much unfermentable sugar, you'll end up with a lower attenuation. It's that simple.

The water-grist ratio affects BIAB more than other methods in that you'll likely have a lower efficiency than the other methods at the same ratio. You can close this gap by using the two pot method, but you'll still probably be cutting this brew pretty close.

I am also curious about one thing you mention. Why are you concerned about unfermentable sugars? Are you worried that there will be more unfermentable sugars if you have a lower efficiency(Which wouldn't be the case)?

If you have a lower efficiency, you won't gain more unfermentable sugars, you'll just extract far less sugar in general (Both fermentable and unfermentable).

Suppose you intend to brew a 5 gallon batch. That will be 20 qts. You'll also have to plan for some boil off as you boil the wort and hops to get the bittering and get rid of any DMS. During that hour boil time you will probably boil off a gallon and you'll want a little more wort into your fermenter to take care of trub loss so lets add half a gallon for that. Hmm, you need to start your boil with about 6 1/2 gallons of wort which is about 26 qts and beyond that you need a little space for the hot break to form and not boil over. I don't think your wort will fit in your 24 qt pot anymore.

RM-MN said:

Suppose you intend to brew a 5 gallon batch. That will be 20 qts. You'll also have to plan for some boil off as you boil the wort and hops to get the bittering and get rid of any DMS. During that hour boil time you will probably boil off a gallon and you'll want a little more wort into your fermenter to take care of trub loss so lets add half a gallon for that. Hmm, you need to start your boil with about 6 1/2 gallons of wort which is about 26 qts and beyond that you need a little space for the hot break to form and not boil over. I don't think your wort will fit in your 24 qt pot anymore.

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It sounds like the largest he wants to go is about 12 qts. So he would only need about 6 qts of extra room for the boil (18 total qts).

Haputanlas said:

I am also curious about one thing you mention. Why are you concerned about unfermentable sugars?

Click to expand...

From Palmer:

The grist/water ratio is another factor influencing the performance of the mash. A thinner mash of >2 quarts of water per pound of grain dilutes the relative concentration of the enzymes, slowing the conversion, but ultimately leads to a more fermentable mash because the enzymes are not inhibited by a high concentration of sugars. A stiff mash of <1.25 quarts of water per pound is better for protein breakdown, and results in a faster overall starch conversion, but the resultant sugars are less fermentable and will result in a sweeter, maltier beer. A thicker mash is more gentle to the enzymes because of the lower heat capacity of grain compared to water. A thick mash is better for multirest mashes because the enzymes are not denatured as quickly by a rise in temperature.

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The way I understand it, "sweeter, maltier beer" is not terribly far off from many ale profiles, but would certainly seem out of place in, say, a pilsner.

I think you will only have to worry about this when you get to a > 2:1 ratio. I don't have direct experience with mashes that are this big in ratio, but I've heard of a lot of BIABers that use a 2:1 or greater with little to no impact.

Right, because of overall space concerns, as well as easing my way in to AG, I intend to brew 2.5-3 gal batches. That would be 10-12 qts post boil. I would have to double my post-boil volume pre-boil to overflow the larger pot.

I originally was scaling 5g recipes to 3g, and planning on ending with only 2.5g in order to compensate for mash inefficiencies.

Haputanlas said:

I think you will only have to worry about this when you get to a > 2:1 ratio.

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What I'm trying to say is that I don't think you'll get a HUGE increase in unfermentables.

Haputanlas said:

What I'm trying to say is that I don't think you'll get a HUGE increase in unfermentables.

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Great, thanks, I really appreciate it.

It also looks like mashing for more than 60min might help get the best efficiency.

GinSlinger said:

Great, thanks, I really appreciate it.

It also looks like mashing for more than 60min might help get the best efficiency.

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It can. But that really depends on what your mash temp is. If it's about 155-157, you'll likely be done WAY before then. But it doesn't hurt to mash at this length.

I like to mash really high and can typically finish up within 45 minutes or so (Less time is even likely to result in the same efficiency at those temps).

My method is pretty much the Deathbrewer method and I probably get over 80% efficiency (could be due to my mill, though).

I know you said you weren't in the market for upgrades, but a decent 20 qt pot can be had for pretty cheap. I use two 20qt pots and they work out great.

I shoot for a 3.75 gallon pre-boil volume. This means I'll need exactly that much water + some to account for grain absorption.

To fill my mash tun, I use a 1.25 qt/lb mash thickness. I heat that quantity to strike temp on the stovetop, and also turn my oven on its lowest setting. I dough in, kill the heat on the stovetop, and stir, stir, stir, stir until my temperature is even everywhere I check it. I turn off the oven and throw the whole pot with my mash in there. This is basically a substitute for insulating the tun, keeps the temperature from dropping.

The second pot basically gets the remainder of the water. I sparge by dunking, and I squeeze my grain bag @ both the mash and the sparge steps. Once I've collected all my wort together in one pot, I quickly rinse the other one, shake out the grain bag and proceed with my boil. A 3.75 gal boil volume fits nicely in a 20qt pot, but I put in 5 drops of Fermcap-S just in case.

This may not end up being exactly what you do - but it's close enough that I figured I'd share. It has worked very well to me and I actually prefer doing double batches this way to single batches of 5 gallons, as I have more variety on hand.

I also think, for what it's worth, that I could get by with using an 8qt pot like yours for the sparge for most batches if I just did the pour-through method using a colander like you suggested.

I supposed I just do it my way because I have two pots and want to be able to use an obscene amount of grain if desired.