BIAB size question

[sgoehner]

I am looking to do my first AG via BIAB. I have access to a 30 qt turkey fryer pot and propane burner. How big of a beer, how many lbs. of grain, will I be able to get away with mashing and then boiling in that 7.5 gallon pot?

I want to do something like a belgian dubbel as it is my favorite style and it will be my birthday beer (March 21), so I have time to let it sit.

Thanks in advance.

 

[cyclonite]

I do 5 gallon batches with the same turkey fryer pot. It can get a bit tight on the boil, but other than that it works great. I would suggest mashing without all of the water, and then adding some more water with about 15 minutes left in the boil to reach your desired volume for the fermenter. This will minimize the probability of a boilover, especially since they are more likely to occur in the first 15 minutes or so of the boil (hot break and typical large hops addition).

 

[Izbozz]

I agree with above. I've done a few BIAB in a 7.5 gallon pot, and (especially with bigger beers) it's a bit tight even during the mash if you try to do it with the full pre-boil volume. That being said, I managed to squeeze about 13 lbs. of grain into the pot without a problem. My only issue with my BIAB batches was efficiency, so I would have some DME on hand in case I needed to bring the gravity up. In the case of a Dubbel, a chunk of your fermentables is sugar so you should be fine. Cheers!

-Frankie D.

 

[dougdecinces]

I ran some numbers and here is what I got:

If you wanted to brew 5.5 gallons of a 1.070 dubbel, you would require 385 gravity points. Assuming 70% efficiency (which is about what you would get with a BiaB no sparge and a loose mash), you would require 550 gravity points from grain.

Then, say, the average gravity points from your grains was 34 pts/lb, that would give you about 16 lb 3 oz of grain. The bad news is that in this instance you can't go more than 1.5 qt./lb without exceeding the capacity of your system. So either you are going to have to sparge to get a decent efficiency, or you will need to keep a pound or two of pilsner DME on hand.

 

[Izbozz]

I ran some numbers and here is what I got:

If you wanted to brew 5.5 gallons of a 1.070 dubbel, you would require 385 gravity points. Assuming 70% efficiency (which is about what you would get with a BiaB no sparge and a loose mash), you would require 550 gravity points from grain.

Then, say, the average gravity points from your grains was 34 pts/lb, that would give you about 16 lb 3 oz of grain. The bad news is that in this instance you can't go more than 1.5 qt./lb without exceeding the capacity of your system. So either you are going to have to sparge to get a decent efficiency, or you will need to keep a pound or two of pilsner DME on hand.

As I understand it, anywhere from 1-2 qt./lb. works just fine, but most homebrewers use around 1.25-1.5 qt./lb. I agree that 16 lbs. of grain for BIAB in a 7.5 gallon pot is alot, but if you thicken up the mash to 1.25 qt./lb then you can add 19.2 pounds of grain to 6 gallons of water. At 34 pts/lb that puts you at around 1.083 at 70% efficiency for a 5.5 gallon batch. For a Dubbel, you're usually adding about a pound of sugar, which will up the OG of that batch to just over 1.090. That's even getting you well into Tripel territory. Cheers!

-Frankie D.

Edit: Ideally, since it's a thicker mash, you would want to try to sparge. Maybe hoist that grain bag out and put it in a large colander over the pot. I still absolutely think an AG Dubbel is possible with BIAB and no sparge, though.

 

[dougdecinces]

Edit: Ideally, since it's a thicker mash, you would want to try to sparge. Maybe hoist that grain bag out and put it in a large colander over the pot. I still absolutely think an AG Dubbel is possible with BIAB and no sparge, though.

Exactly. There's no way in hell you're getting 70% efficiency on BiaB no sparge with that thick a mash. My mashes usually end up about 1.75-2 qt/lb and I get around 68% efficiency no sparge.

 

[frailn]

This is the set up I use and do BIAB exclusively. Following the previous example of a 1.070 original gravity beer, your pot is way too small for five gallons to do a full BIAB. follow my example:

5 gallons of beer is the goal
16 pounds of grain.
Grain absorption - .09 x 5 = 0.45 gallon
Boil off rate - 0.83 x 1 = 0.83 gallon (your rate might be different than mine)

So, at this point you need 5 + .45 + .83 = 6.28 gallons in the pot to start your BIAB.

However, you also need to consider grain displacement. I use .0825 and multiply it by the pounds of grain
.0825 x 16 = 1.32

So, add that to the previous number and you now need a pot that can hold 7.6 gallons of water. If you want to account for kettle and fermenter loss, add to that number.

For a full BIAB, you could however do a 2.5 gallon batch.

16 pounds of grain is just pushing it past the limit.

 

[sgoehner]

Thanks for all of the responses guys, I have a lot of reading and thinking to do. I should have put in the OP, that I am looking at doing the NB Belgian Dubbel. I just looked at the kit inventory, and it is an OG of 1.065, and an ingredient list as follows.

Mash
10# Belgian Pale
.5# Caramunich
.25 Belgian Special B

Boil Additions
1 oz Tradition (60)
1# Dark Candi Sugar (15)
1oz Hersbrucker (10)

Mash for 60 at 151

Mashout for 10 at 172

So, it looks like a little under 11 lbs of grain total for this kit.

So for those that were talking about 16lbs of grain, how does that change things?

 

[dougdecinces]

It looks like they are expecting you to get about 72.6% efficiency for a five gallon batch. I would err a little low and guess you'd get 68-70% efficiency. That would mean you would only need 11-18 extra gravity points. Have them add half a pound of Belgian Pilsner to your order to account for that. 1.065 is on the low end of the style anyways, so if you overshoot your mark, no harm done.

Also, if you plan on racking to secondary, you will want to the batch to be 5.5 gallons (to account for the trub you would lose when racking). If so, you would need to add an additional 30-40 gravity points.

The good news is that even if you ended up mashing 12.75 lbs of grain (10.75 in the recipe plus an extra 2 lb pils to account for the lower efficiency and higher reqd. volume) you would still be able to easily do so:

Mash in to 6.5 gallons of water. Your mash ratio will be a hair over 2 qt/lb. Expect to lose approximately 1.5 gallons of water due to grain absorption. That would give you a pre-boil volume of 5 gallons. You would need to add an extra 1-1.5 gallons of water to the boil to get a suitable pre-boil volume, but that should work.

 

[frailn]

dougdecinces is right. Mashing with less water and adding some later is the way to go. Like he says, mash in with 6.5 gallons of water.

But, I would suggest - if you have a separate stock pot that holds four gallons or even a big metal bowl - any container that will hold four gallons - add two gallons of 180 degree water to that, then after mashing, drain your bag in the boil kettle, then sit in the two gallons 180 F water for ten minutes. Pull, drain and squeeze the bag, then add that extra two gallons of sparge wort to your boil kettle.

The grain bag will be at around 152 degrees, when you put it in the 2 gallons of 180 F water, it will drop the temp to 170. Perfect for sparging and getting those extra sugars out of the grain.

Those grains will be hot - so find some rubber gloves to put on when draining and squeezing the bag

 

[BetterSense]

I use an identical turkey fryer to brew 5 gallon batches. With 10 pounds or less of grain, I use my aluminum fryer basket and put the bag in that. I always use as much mash water as I can fit in the pot. After the mash I pick the fryer basket up with a rope, put a grill under it and set it on the kettle. Then I sparge it by squishing the water out of it with my mad scientist gloves and pouring more hot water (from the stove) through the grain until the kettle is as full as I dare. With larger grain bills, I have to skip the fryer basket, and I get a thicker mash and less sparge water, so efficiency drops off fast. If you have another container to set the bag into to sparge, it helps with efficiency on big batches, but it's messy. I easily get 75% with 10-11lb of grain, though.

 

[sgoehner]

Thanks for the update advice, that sounds completely doable and it makes sense. I hope to brew this on the 13th, so I will more than likely have a couple of questions before then, and will let you guys know how it goes.

 

[smokewater]

I use an identical turkey fryer to brew 5 gallon batches. With 10 pounds or less of grain, I use my aluminum fryer basket and put the bag in that. I always use as much mash water as I can fit in the pot. After the mash I pick the fryer basket up with a rope, put a grill under it and set it on the kettle. Then I sparge it by squishing the water out of it with my mad scientist gloves and pouring more hot water (from the stove) through the grain until the kettle is as full as I dare. With larger grain bills, I have to skip the fryer basket, and I get a thicker mash and less sparge water, so efficiency drops off fast. If you have another container to set the bag into to sparge, it helps with efficiency on big batches, but it's messy. I easily get 75% with 10-11lb of grain, though.

Iuse the same pot and do basically the same thing except I sparge in a 5 gallon bucket.

Start with 6 gallons to mash.

heat 2 gallons of sparge water on the stove.

Pull bag after mash and put it in the bucket. Pour sparge water over it and let it sit.

Heat wort to 170. squeeze bag in bucket and place it back in boil kettle at 170 for 10 minutes.

Pull bag, combine liquid for boil volume. I leave the bag in the empty sparge bucket and add any liquid to the wort during the boil to offset evaporation a little.

 

[dougdecinces]

Thanks for the update advice, that sounds completely doable and it makes sense. I hope to brew this on the 13th, so I will more than likely have a couple of questions before then, and will let you guys know how it goes.

You're welcome. You caught me at a good time. I had nothing to do at work and I was in the process of figuring out how to make a 1.085 OG doppelbock in my BiaB system, so all the information was still fresh in my head.