How many BTU's need to boil 3 gallons? - Home Brew Forums

 Home Brew Forums > How many BTU's need to boil 3 gallons?

03-04-2013, 12:28 AM   #1
poppafritz
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Feb 2013
Gig Harbor, WA
Posts: 22

So i am looking into getting a propane burner to do my wort in because after my first batch i learned that my stove top is not up to the challenge. Looking around and doing some math i have learned a few things. I wanted to double check my math with you all and see if i am doing this right.

My tap water comes out at 55° and water boils at 212°.
1 gal. of water weighs 8.3 lbs
Weight X Differences of Water temp to boil temp = BTU per gal
8.3 x (212 - 55) = 1303.1 BTU's to boil 1 gal.

If i am boiling 2.5 gals of water then i will need a burner with a BTU rating of 3257.75 BTU's to boil my pot. Now this math is with the idea of 100% heat transfer from source to water, this number is not quite right. Under the right conditions were looking at more like 75% to 80% so that bumps up our BTU's to roughly 3909.3 or rounded to 4k BTU's

With that said... these two burners should be more then enough right?

http://www.amazon.com/Cajun-Cookware...s=turkey+fryer

http://www.amazon.com/Bayou-Classic-...s=turkey+fryer

03-04-2013, 12:46 AM   #2
theveganbrewer
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Sep 2011
Beaverton, OR
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Bayou Classic SP10 or the SQ14 will both work. I see the SP1 is pretty cheap, will also do the job easily.
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03-04-2013, 01:31 AM   #3
BlackDogBrew
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Feb 2013
, Michigan
Posts: 34
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This Walmart Turkey Fryer works well. Comes with Burner, regulator, hose and a 30 qt alum pot. My local Walmart had it in stock, even though it says out of stock online. Check the ship to store or local store inventory checker.

I used it for my 3 gal extract brews. Easy to bring to temp, and easy to hold from boil overs.

03-04-2013, 02:01 AM   #4
poppafritz
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Feb 2013
Gig Harbor, WA
Posts: 22

Thanks guys i think i have a much better idea of what im looking for now.

03-04-2013, 04:10 AM   #5
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Oct 2011
, Pa
Posts: 743
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The formula doesn't take into consideration change of state. The 1lb 1 degree = 1 BTU doesn't apply during change of state (boiling). Add another 960 BTU/Hr per lb. to change state, add to that number the BTU for TD. It takes a lot of energy to change state. So, you'll need about 20K BTU/Hr to change state and another 4K BTU/Hr for TD = 24K BTU/Hr. The Cajun is slightly undersized at 20K BTU/Hr. Unless, it can be throttled way down, the 185K at 20 PSI is over kill for boiling 2.5 gallons. Either burner will work. However, thay may not be the best choice for your process. Camp Chef makes a 30K and a 60K that can be throttled down. The Blichmann is 72K at 10 PSI and can be throttled down.

03-04-2013, 04:14 AM   #6
thargrav
Registered User
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Dec 2009
Huntsville, Alabama
Posts: 821
Liked 38 Times on 35 Posts

Quote:
 Originally Posted by poppafritz So i am looking into getting a propane burner to do my wort in because after my first batch i learned that my stove top is not up to the challenge. Looking around and doing some math i have learned a few things. I wanted to double check my math with you all and see if i am doing this right. My tap water comes out at 55° and water boils at 212°. 1 gal. of water weighs 8.3 lbs Weight X Differences of Water temp to boil temp = BTU per gal 8.3 x (212 - 55) = 1303.1 BTU's to boil 1 gal. If i am boiling 2.5 gals of water then i will need a burner with a BTU rating of 3257.75 BTU's to boil my pot. Now this math is with the idea of 100% heat transfer from source to water, this number is not quite right. Under the right conditions were looking at more like 75% to 80% so that bumps up our BTU's to roughly 3909.3 or rounded to 4k BTU's With that said... these two burners should be more then enough right? http://www.amazon.com/Cajun-Cookware...s=turkey+fryer http://www.amazon.com/Bayou-Classic-...s=turkey+fryer
At best a open flame on the bottom of your pot is 50% efficient but your efficiency could easily drop to 25% during a windy or cold day.

03-04-2013, 04:16 AM   #7
thargrav
Registered User
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Dec 2009
Huntsville, Alabama
Posts: 821
Liked 38 Times on 35 Posts

Quote:
 Originally Posted by VladOfTrub The formula doesn't take into consideration change of state. The 1lb 1 degree = 1 BTU doesn't apply during change of state (boiling). Add another 960 BTU/Hr per lb. to change state, add to that number the BTU for TD. It takes a lot of energy to change state. So, you'll need about 20K BTU/Hr to change state and another 4K BTU/Hr for TD = 24K BTU/Hr. The Cajun is slightly undersized at 20K BTU/Hr. Unless, it can be throttled way down, the 185K at 20 PSI is over kill for boiling 2.5 gallons. Either burner will work. However, thay may not be the best choice for your process. Camp Chef makes a 30K and a 60K that can be throttled down. The Blichmann is 72K at 10 PSI and can be throttled down.
The conversion for boil-off is 8000 BTU per gallon, before factoring in inefficiencies. And gas fired is about 50% efficient at best.

03-04-2013, 05:09 AM   #8
OrdinaryAvgGuy
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Jan 2013
Cary, NC - North Carolina
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Quote:
 Originally Posted by theveganbrewer Bayou Classic SP10 or the SQ14 will both work. I see the SP1 is pretty cheap, will also do the job easily.
For 3 gallons I would skip the math and go with this.

+1 on the SQ14. Got mine on Amazon for less than \$50 shipped.
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03-07-2013, 12:47 AM   #9
poppafritz
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Feb 2013
Gig Harbor, WA
Posts: 22

Thanks guys ill look into some of the other options here.