How many BTUs needed for 5-gal batches

Brewing Processes
1

How much heat do you need to boil enough water for 5 -gal batches in say 20 minutes to a boil?

Thanks in advance for hour help.

2

I made some calculations like that in this thread:
https://www.homebrewersassociation.org/forum/index.php?topic=17898

3

Basically 1 BTU will move 1 pound of water 1 degree Fahrenheit. There are 8.35 lbs in 1 gallon. There are 8.35*5=41.75 lbs in 5 gallons. To take water from 75 to 212 therefore requires: (212-75)*41.75=5720 BTU.

How long that takes depends on the BTU rating of your burner. A 60000 BTU burner puts out 60K BTU over a 1 hour period. To calculate how many minutes you need the BTU rating per minute: 60000/60=1000. So in a perfect world a 60K burner can take 5 gallons of beer from 75F to boil in 5.7 minutes. In reality the burner wastes lots of heat. Probably there is 20-30% waste. So you need to scale back the BTU rating of the burner by some amount. I am not sure of the exact inefficiency. It depends on conditions and burner design.

4

Wind, ambient temps etc also play into how efficient the burner is. are you brewing indoors or outside?

5

With a propane burner, I’ll have to brew outside.

Thanks

6

Are you trying to boil all the water needed for a 5 gal batch? (And if so, why?) That would require something like a 120,000 BTU/hr burner running at full blast.

Or do you want to bring ~6 gal of wort from mash temp to a boil in 20 minutes? That’s much more feasible.

7

I planning on doing BIAB, so I’ll be bringing 7 or 8 gallons of water to strike temp, draining the bag and then bringing that to a full boil.

8

If you’re going to be putting the bag into all that water at once, be sure to keep an eye on your pH.  That’s a lot of water for the grain to buffer.

9

Without using any calculations, I stepped up my turkey burner by swapping out the included 10 psi-regulated hose to a 30 psi one.  This SIGNIFICANTLY decreased my time to boil.  Sounds like a jet engine now.

10

I’ve wondered about the different regulators available and how easy it is to regulate temps for all the different conditions that one might encounter.  I suppose the regulators with the higher pressure will heat the wort faster, but use more gas in the process.

Do you need different gas cylinders to work with regulators with different pressures, or will the regular propane  gas cylinders work with all of them?

I’m planning on doing mostly 3-gal batch sizes, but want the capability of doing 5-gal batches also.

If I get one of the185,000 BTU or 210,000 BTU burners that are on the market, can I control the flame well enough to add just a bit of heat to a 3-gal batch to raise my mash temp back say 3 or 4 F to get it back to “specs” if the wort is cooling down too much before enough time has elapsed for good conversion?

Will be higher rated BTU burners do the smaller batches efficiently or should I get a a burner in the 60,000 BTU range?

Thanks in advance for you advice.

11

I do 3 Gal batches often and believe it or not i use my camp chef explorer stove that i have for camping. It only has two burners at 30,000 BTUs each. I do not do brew in the bag though. i can heat 3 gals of strike water at 4800’ in a reasonable time. i can bring to boil 5 to 6 gallons in a timely manner. It takes me 3.5 to 4 hrs on brew day if i prep the day before. i am in no hurry though its a hobby and i enjoy it. i use to do 5 gal batches on it and it did take longer but not by much. i would start heating my wort while draining my sparge in a large container. Good luck.

12

Once I reach boil, I turn it way down just to keep it rolling.  I figure I would use the same amount of gas to reach the same result:  a 10-psi regulator using less gas but taking longer to get to boil VS a 30-psi regulator using more gas but reaching boil quicker.  Too lazy to do the math or a real-time comparison.

The 30-psi regulator I use fits the standard grill-style propane tank.  You just have to make sure you can disconnect the original hose from the burner.

Yes, you should be able to control your boil enough with the needle valve on the regulator.  Believe me but you will at one point move on to 5-, 10- or 15-gallon batches.  Making 3-gallon batches are great for experimenting but the one time you make the greatest beer ever, you will run out of it quicker.

Hope this helps.

13

My standard batch size is 3.5 gallons, and I use a Camp Chef Pro 30, which is basically a single burner version of the Explorer.  The Pro 30 is not fast, but it is incredibly fuel efficient compared to a 60K+ BTU blow torch.