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 Home Brew Forums > Grain Bill Hand Calc - Extraction% & Brewhouse%
04-10-2012, 07:44 PM   #1
BrewWorm
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 Grain Bill Hand Calc - Extraction% & Brewhouse%

I'm set on doing hand calculations for my grain bills (and hops for that matter) so I can really understand what's going on in my mash tun. When I get good consistent brews, then I'll switch to the software.

For now, I'm trying to get a firm handle on extraction percentages and brewhouse efficiency. Basically do you factor in the extraction percent into the overall brewhouse efficiency?

As I understand it now:
Extraction %: How much extract you can get from a unit of malt. This will vary from malt to malt, but is usually in the ~75 - 80% range, correct?

Brewhouse efficiency: How much of the sugars you can actually extract from the grain. Does this include the extraction % or is more just about how much extract you can lauter and separate from the grain bed?

So for grain calc say that I want to hit 13 Plato in a 15gallon batch.

15gallons = 125lbs of H20
125 * .13 = 16.25 lbs of extract

Would it be 16.25/(brewhouse eff) or 16.25/(brew eff * extraction %)?

I'm guessing the latter so if I had a 80% efficiency and 2row I would get
16.25/(0.8 *0.8) = 25lbs of grain.

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04-10-2012, 09:11 PM   #2
jimbot
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Let's try this in SG units. You want 1.053 SG (13 Plato) in 15 gallons of wort.

15 gal * 53 = 795 gravity points.

Now you figure your malt bill out so that it adds to that many points. A pound of Pale 2-row is 36 points. Let's saw brewhouse efficiency is 75%, so that pound is now 27 points.

795 points / 27 per pound= 29.4 pounds of Pale 2 row.

Somehow, we got the same result, but I'm not sure how you did that. I don't think you should be using the weight of the water at all.

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04-11-2012, 03:04 AM   #3
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The plato target gives me the percent of sugar to water, so using the weight of the water I can calculate how much sugar I need in that water.

Then it's just trying to figure out how much malt I need to mash to end up with that weight of sugars in the brew kettle. Which is what I'm struggling with.

For example if the starch conversion is 100% efficient for 2row, you'd still end up with only 80% of the weight of the grain in extract. So if I need 16 lbs of extract I would need 20 pounds of 2row if I could mash and lauter PERFECTLY.

So "brewhouse efficiency" should refer to just how close I can get to this 80%? If I can get 80% of the available sugars from the grain, that means that the weight of grain should be equal weight of needed extract/0.64 or at 75% efficiency I'd divide by 0.56.

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04-11-2012, 03:40 PM   #4
jimbot
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I think you have it.

I still think its a lot easier with SG units though.

--Jimbot

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04-11-2012, 06:30 PM   #5
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Quote:
 Originally Posted by jimbot I think you have it. I still think its a lot easier with SG units though. --Jimbot
Probably. We get pretty close to the same numbers. At 75% my method gives 28.5 lbs where as you were getting 29.4lbs. Maybe this is because when I calculate the weight of the water I used 8.3 lbs when I should be using the weight of wort. That would give me ~30lbs needed.

I'll just start brewing and calculate my BH efficiency. That way as long as I calculate the weights the same every time, I should be able to hit my numbers.
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