Author Topic: Pot size needed for both 3-gal and 5-gal batches for BIAB?  (Read 11292 times)

Offline Lazy Ant Brewing

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Pot size needed for both 3-gal and 5-gal batches for BIAB?
« on: August 02, 2014, 12:05:42 PM »
I'm thinking about getting into Brew in a Bag and I'm trying to get basic info. 

I'd like to do both 3-gal and 5-gal batch sizes.  I could try more different recipes with the small size and then when I found one I really liked could scale it up to the 5-gal batch.

 From what I've seen online, it seems like turkey fryer pots are less expensive than basic brew pots (there is something in a name isn't there?), but most of the turkey fryer pots I see are 32 quart. I thinking that the 32 qt size should be big enough for the 3-gal batch, but probably not for the 5-gal batch.

I did see one 50 qt. pot advertised and wondered if there is any drawbacks to using that size pot for 3-gal BIAB?

I assume you would have to get a custom made bag or make your own for a pot that size.

Thanks in advance for your advice.
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Offline Slowbrew

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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #1 on: August 02, 2014, 12:50:24 PM »
Many on the board have more experience with BIAB than me but I can tell you that you can use the samepot for 3g as would for 5g.  The most important factor on kettles is make sure they are big enough to boil the entire volume of wort.  I would look for a reasonable priced 8 to 12 gallon pot to make sure you have head space for the hot break.

You can make your own bag, if you can sew but you can also get some really large bags at you LHBS.

I'm sure others will chime in.

Have fun!!

Paul
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Offline erockrph

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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #2 on: August 02, 2014, 03:28:52 PM »
You will probably have to adjust your boiloff a bit if you're using the same size pot for both 3 and 5 gallon batches, but otherwise I see no issues.

I do 3 gallon semi-BIAB batches using a separate 5-gallon beverage cooler as a mash tun (to help hold temps during the mash), and boil in a 5-gallon kettle on my stovetop. I can get 4 gallons up to a boil, and boilovers aren't an issue with Fermcap.
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Offline reverseapachemaster

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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #3 on: August 02, 2014, 03:46:25 PM »
A 32 quart pot would be ok for a five gallon BIAB batch as long as you stay below 1.070 on your five gallon batches. That may not be a limitation you want on your brewing.
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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #4 on: August 02, 2014, 07:30:00 PM »
I use different kettles for 3.5 and 5.5 gallon batches.  Kettle geometry matters when making beer, as it affects evaporation rate, hop utilization, and immersion chiller effective height.  Ideally, one wants a kettle with at least a 1:1 height-to-diameter ratio at roughly twice the end of boil volume. 

With that said, Northern Brewer is selling a fairly low-cost 10-gallon (actually 9.63-gallon) stainless steel kettle that has a 1.2:1 height-to-diameter ratio at 9.63 gallons and a 1:1 height-to-diameter ratio at 8 gallons.  This kettle is sold as their 10-gallon Tall Boy kettle.  The price point is a very good for a buy once, cry once kettle with a tri-clad bottom. 

Offline Lazy Ant Brewing

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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #5 on: August 04, 2014, 03:08:13 PM »
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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #4 on: August 02, 2014, 12:30:00 PM »
Quote
I use different kettles for 3.5 and 5.5 gallon batches.  Kettle geometry matters when making beer, as it affects evaporation rate, hop utilization, and immersion chiller effective height.  Ideally, one wants a kettle with at least a 1:1 height-to-diameter ratio at roughly twice the end of boil volume. 

With that said, Northern Brewer is selling a fairly low-cost 10-gallon (actually 9.63-gallon) stainless steel kettle that has a 1.2:1 height-to-diameter ratio at 9.63 gallons and a 1:1 height-to-diameter ratio at 8 gallons.  This kettle is sold as their 10-gallon Tall Boy kettle.  The price point is a very good for a buy once, cry once kettle with a tri-clad bottom.

I was thinking about buyng an 80 qt. pot made of 2 mm aluminum with a vegetable strainer basket and using it for both 3-gal and 5-gal BIAB batches. If I would  just take a moderate hit to my efficiency I wouldn't really care too much.  If it would severely affect the quality of one of the batch sizes I might have to rethink it.
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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #6 on: August 07, 2014, 01:11:43 AM »
In my humble opinion, purchasing an 80-quart kettle for what you plan to do would be a huge waste of money.  An 80-quart (20-gallon) kettle is way too big for 3 and 5-gallon BIAB batches.  Your liquid column would be extremely shallow.  A 40-quart stockpot is more than large enough to handle 5-gallon BIAB batches.

There are 231 cubic inches in a gallon; therefore, 3 gallons has a volume of 3 x 231 = 693 cubic inches.  The volume of a cylinder is equal to its radius x its radius x 3.14 x its height. The typical 80-quart aluminum stockpot is around 18 inches wide; hence, each inch of stockpot height has a volume of 9 x 9 x 3.14 x 1 = 254.34 cubic inches.  Three gallons of wort in a kettle this large has a liquid column height of 693 / 254.34 = ~2.73 inches.   Five gallons of wort in a kettle this large has a liquid column height of 1155 / 254.34 = 4.54 inches.    Your evaporation rate during boil is going to be significantly higher than it would be with a 40-quart kettle.  Immersion chilling a liquid column this short is not going to be much fun as well.
« Last Edit: August 07, 2014, 01:14:31 AM by S. cerevisiae »

Offline archstanton

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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #7 on: August 07, 2014, 01:50:51 AM »
When I make an IPA I use about 9 gallons of water and  around 15 pounds of grain.  That will not fit in a 40 qt pot.  I agree that 80 qts is overkill, but I recommend a 50 -60 qt pot. You will be much happier with the extra room when pulling out the bag and the hot break occurs. 

There is no real issue with what you want to do, a plate chiller or ice bath to cool the wort takes care of the immersion chiller, and adding a little extra water to account for the extra boil off is simple. No problem.

Offline ynotbrusum

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Re: Pot size needed for both 3-gal and 5-gal batches for BIAB?
« Reply #8 on: August 07, 2014, 10:57:32 AM »
Sizing is a bit problematic as all above have said.  I have trouble dialing in the boil off in my 60 quart when doing 5 gallon batches for the reasons mentioned, but adding a little top off water remedies things pretty well.  And since I do mostly 10 gallon batches using a separate mash tun, the 60 quart was my compromise size.  I have a 30 quart for extract and smaller batches...YMMV, of course.  Both have the tri-clad bottom, which I feel is beneficial to evenly disperse temperature at the boil - less scorching potential.
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