BDP

I can't fault your spreadsheet.

Why is there a difference? I don't have your previous sheets handy so we will look at this one and then maybe you can look at the older ones.

If you look on page 40 of BCS in the malt section you will see that they go on about the "fine grind dry basis number". As I understand it that's the maximumum amount of sugars you could extract, in a perfect setting, in a laboratory. BCS says they can extract 70% of those theoretical sugars and their recipes are based on that. If you look in BIABacus, Section Y, you will see that BIABacus says you can extract 80%. I don't know where that number came from but I do know that there have been a huge number of practical brews measured and collated to come up with some of the "constants" used. 80% works for me. If you enter 70% into the FGDB column of your actual grain bill and 4% into the MC column, in Section Y, for those grains you have substituted and into the original grain bill for those you didn't you will see your actual grain bill, Section C, change to reflect the extraction.

Still not the same as BCS .

If you look at page 41 they talk about volumes. Look at their KFL. 22.7l at the end of the boil and 20.8 into the fermenter. A KFL of 1.9l. Section X allows you to overwrite the BIABacus defaults by entering 1.9l into the KFL area.

Now the grain bills match very closely.

But... you don't want that.... take them all out again and go with BIABacus.

Now ... with all those numbers floating around, an astute observer, such as youself, will say "Hang on. I was told to use 20.19 as the VAW but BCS has 22.71" Have a read here where PP explains all.

This shows again the problems you get trying to copy recipes from other sources.


Which now makes me wonder whether I should use that 70% in all BCS recipes.

Don't worry...start brewing.

majorphill wrote:Which now makes me wonder whether I should use that 70% in all BCS recipes.

All is good so no need to get worried about anything . [*See my note at the end Phill.]

This is a pretty common question and I have been wondering how to write it into the BIABacus help - just this morning in fact. (Gotta love this synchronicity.) I'm going to put it into a sort of FAQ section (it's actually going to be 'Appendices' not FAQ's) but I still can't work out how to title it. I'll use this thread as a rough copy...

[center]The BIABacus says I need more (or less) grain than the original recipe.[/center]
The first thing to realise is that if two brewers brew the same Volume of Ambient Wort (VAW) on the same equipment (therefore same kettle efficiency) they will always use the same amount of grain. So, when a discrepancy occurs between the fermentable bill of the original and scaled recipe it is almost always due to a misunderstanding - we are comparing apples with oranges.

For example, here is a recipe (insert your file from post #1) where the original recipe uses 5327 grams of grain whilst the scaled recipe only uses 4960 grams. If we look a little closer though, we'll notice two things....

A discrepancy of VAW

Original recipe is 22.7 L whilst the scaled recipe is 24.27 L. If the kettle efficiency was the same on both systems, then you would obviously think that the scaled recipe would need 24.27/22.7 = 1.069 x the grain bill of the original recipe which would equal 5695 grams.

So what is going on?

A discrepancy of Kettle efficiency

The original recipe comes from a book (Brewing Classic Styles) and it is one of the few books that actually states some assumptions it has made. Even with these clarifications, we still have problems. For example, most of the recipes as far as we can see have been designed as extracts and then converted to all-grain. This affects a few things but the main problem we have is that the book gives a generic kettle efficiency figure of 70%.

Here is how this file looks when I match the VAW's and kettle efficiencies. See how I set the KFL to zero in Section X and the VIF in Section B to 22.7? That's is an easy way to force a VAW number . See now the scaled grain bill is 5584 grams which is within 100 grams of the 5695 above?

Set the BIABacus free

If you let the BIABcus free and let it auto-estimate, you will see that the kettle efficiencies rise from 70% to 84.5% (just delete the 70% in Section X of the above file.) Now you see we need only 4625 grams!

But, if we go back to the original person's file, they wanted 24.27 litres of VAW versus the original recipes 22.7 litres so we now need to multiply 4625 by 1.069 and we get 4944 grams which is very close to the original 4960 grams of the BIABacus.

Let me know if you have any questions on the above ,
PP

*I intended to explain the difference between kettle efficiency and extract potential here but I think I should wait until I am sure that you and BDP understand the above first. It's a hard area so make sure you are comfortable with the maths above and then we'll get into extract potential. The major confusing thing is that the 'percentages' of these two things, kettle efficiency and extract potential, 'hover ' around the same region but they are actually two entirely different things.

BDP, PP

I am with you in the maths (and I love the method of forcing VAW. I have always modified KFL but not VIF to get want I wanted).

I believed that extract potential (which you've not yet discussed) was the maximum theoretical amount of sugar that you could get from a source. I can now see that I was getting that mixed up with the amount that your process (maximum practical) could get from the source i.e. kettle efficiency as I understand it. ..I think ..

But it's still a headspin .

When would you use Section Y ?

Majorphill

[center]Post 1 of 3[/center]
I'm glad that made at least a little sense and I think this post here will give you another way of seeing things. This stuff is not easy and not many people understand it, even a lot of commercial craft brewers. Even if they had the education and tools (like BIABacus) available to them, it is still a mentally tricky area (percentages of percentages) and, when it "clicks", it is really simple.

So certainly expect a headspin and even when you initially 'get it' and it all makes sense, try explaining it to a third person and that will give you a thousand more major headspin as all the terminology, definitions and metric/US variations muddy the waters to a ridiculous extent. It becomes not only a percentage of percentage problem but also a percentages on percentage on unit on unit on term on term etc etc.

The following is the best analogy I have been able to think of so far to explain this whole area.

[center]Planning a Journey in a Car (Beginners)[/center]
Let's say we want to work out how much fuel we need to buy to go on a journey in our car. There are four questions we need to ask and answer...

What distance are we travelling? (VAW)

How many miles or kilometres is the journey? That's the most obvious question of all and in planning a brew, we can think of that as being the Volume of Ambient Wort (VAW). The longer the distance, the more fuel needed.

Level Road or Uphill? (OG)

If we are driving along a flat plain we will need far less fuel than if driving up a steep incline. We can think of the gradient of the incline as being like the Original Gravity (OG) of our recipe. The higher the incline the more fuel we will need.

The Quality of the Engine (Kettle Efficiency)

If my engine is better at converting petrol/gas to energy than your engine, obviously I will need less fuel than you to go on the same journey.

The Quality of the Fuel (Extract Potential)

If I use high octane fuel and you use low octane fuel, I will need less fuel than you to go on the same journey.

[center]Putting all that Together (Harder)[/center]
Distance x Incline = Minimum pure Energy 'Volume' Needed
(VAW x OG = Minimum Table Sugar 'Weight' Needed)

If 100% energy fuel (table sugar) was available then...

Actual pure Energy Volume Needed = Minimum pure Energy Needed / Engine Efficiency % [Can also think of this as fuel economy. E.g. Miles/gallon or Litres per 100 kms]
(Actual Pure Sugar Weight Needed = Minimum pure Sugar Weight Needed / Kettle Efficiency %)

If only low 'octane' fuel was available (malts) then...

Actual pure Energy Volume Needed = Minimum pure Energy Needed / Engine Efficiency % / 'Octane %'
(Actual Pure Sugar Weight Needed = Minimum pure Sugar Weight Needed / Kettle Efficiency %) / Extract potential%

I think before you move onto the next post, just have a beer and make sure the above makes some sense. No need to understand the maths, just the general idea.

[center]Post 2 of 3
An Example of the Above (Advanced)[/center]
Let's go back to the original file posted here. I'm going to use US measurements for this example as it relates better to the hydrometer, OG etc.

In BDP's recipe, pure energy needed was 6.42 gallons of 1.051 OG gravity wort. In this sort of brewing maths, what we do is get rid of the 1.0 of the gravity. In other words, we just think of 51, not 1.051 so...

"Distance x Incline" = Minimum Pure Energy Needed
= 6.42 * 51 = Minimum of 327.4 US 'sugar points'

The next thing we need to look at is 'fuel economy' or kettle efficiency. This varies greatly between country and city driving (low and high OG brews or, more correctly, high to low liquor to grain ratios).

All software (besides BIABacus) asks you to provide a figure for your fuel economy and most users of that software use the same figure no matter what driving conditions they are planning. The BIABacus looks at each journey (recipe) and then calculates your likely fuel economy for you. In this example, it is estimating that your 'fuel economy' will be 84.2%.

So now we need to up our pure energy requirement to...

327.4 / 84.2 * 100 = 388.8 US 'sugar points'

We are not using 'rocket fuel' (table sugar) on this journey. In fact, we are using fuel that only has 76.8% of the energy of 'rocket fuel' (see note at top of BIABacus Section Y). The other 23.2% by weight is water and other 'non-burnables' so...

[center]Let's look at what the BIABacus has come up with...[/center]
The BIABacus in Section C on the right hand side says you will need to buy 10.93 pounds of malt that yields 35.49 ppg (35.49 ppg is 76.8% of 46.2 ppg which is the 'miles per gallon' you can get with table sugar).

10.93 * 35.49 = 387.9

And this equals (after minor rounding) the 388.8 pure energy we needed.

Don't worry about the numbers too much, just the principles. I have only put numbers in the above to prove that the principles/analogy is factually correct.

PP

* Phill, use Section Y for high octane fuel such as table sugar or extracts. The BIABacus default works very well though for the overwhelming majority of all-grain recipes.

PP

Slow down. I'm enjoying a nice mild and I think I'm going into a tailspin. (oversteer using your analogy).

Majorphill

[ Phill. Sorry! I do fully understand though. Looking forward to having a beer with you and maybe Nev in the not too distant future. I'll PM you if anything comes up Freo way ]

[center]Post 3 of 3
Volume of Ambient Wort (VAW) versus Volume into Fermentor (VIF)
Kettle Efficiency versus Fermentor Efficiency[/center]
The above questions are actually exactly the same but cause massive confusion due to the poor terminology/education/propaganda/design put out by the other 'fuel companies'.

This is the hardest analogy of all to fit in but the difference between VAW and VIF (or EAW and EIF) is nothing more than your Kettle to Fermentor Loss (KFL). If we were driving a car, things that would contribute to our KFL would be fuel-wasting practices such as warming the car up (mash tun deadspace), detouring (dilutions) or the amount of traffic lights on your journey (the time you sit there idling and wasting fuel and not moving forward.)

I think that is enough 'analogising' for today - lol!

Please let me know if they work or not.


PP