Have re-checked everything Phil and this conversion is good to go. At the end of the post you'll find a copy of The Calculator with the inputs described below.
The below will be be a long read but I'm not sure there is
a short helpful way of doing and explaining recipe conversions. Anyway, here you go...
Firstly, I have just downloaded the latest version of The Calculator from the site so as we are on the same page.
First Page of The Calculator - Volume and Grain Bill Totals
On the first page change the figures in red to suit your equipment. So, change the "Diameter of Kettle" from 45 to 35.5 cm. Secondly change the "End of Boil Gravity (OG)" figure from 1.048 to 1.042.
But, what figure should you use for Brew Length?
You should ignore the 26.5L pre-boil volume figure provided by Jamil and John. Instead, look at the bottom of page 41 of their book and you will see that they have said, "All of these recipes are designed to leave 22.7L of wort in the kettle after the [60 minute] boil." These figures are far more accurate to work with as they are post-boil (post-evaporation.)
I personally think that, where possible, a 90 minute boil should be done as it avoids a lot of potential problems. The Calculator is already set at 90 minutes so no need to change that figure.
So, the last thing we need to do on the first page is keep changing the Brew Length figure (in red) until the "End of Boil Volume (Batch Size) equals 22.7 L.
An 18L Batch Size gets very close to this so let's use that. (In reality
, you will end up with more than 18 L of beer as The Calculator is very
generous in its trub allowances.)
Now that we have done the above, we can see that The Calculator says we need 3928 g
of grain. The other crucial figure we get from the first page is "Water Required is..." 31.5 L
Let's go to the second page now...
Second Page of The Calculator - The Grain Bill
The Calculator allows you to either put in the original weights of the recipe or their percentages. Either way will work. I'll use the percentages that Jamil and John have listed...
So, in Cell B6 I type, 62.5, B7 I type 25 and B8 I type 12.5. The Calculator tells me in G6, G7 and G8 that I need 2,455 g, 982 g and 491 g of grain respectively.
(If you didn't have percentages readily available you should have typed in 2260 to Cell D6, 900 into D7 and 450 into D8. You can do this now and see that the result is the same.) So, you'll need the following grain bill...)
2455 g English Pale Ale
982 g Flake Barley
491 g Roasted Barley
Third Page of The Calculator - The Hop Bill
What we need to look at on this third sheet, once again, is the figures in red. The first one is the Original Gravity of Recipe. (This is a bit unclear but it means the Original Gravity of the original
recipe.) In most cases, you will never need to change this - in fact, I can't see any cases where it would need changing for a straight recipe conversion so perhaps BIABrewer should un-"red" this figure
The second red figure is the End of Boil Volume. This is
important. Once again, it is a bit unclear that it requires the original "End of Boil Volume" of the original
recipe - it might be better if future versions of The Calculator just had "zero" as the default???
Anyway, the End of Boil Volume of the original recipe is not a problem in our case as we have already adjusted our recipe to assume a brew length that will give us an end of boil volume of 22.68 L.
Although we are doing a 90 minute boil rather than Jamil and John's 60 minute boil, I would still throw the hops in at 60 minutes. (I usually do this.)
You will notice that the result on the right is exactly the same as Jamil and John's recipe. This is because our end of boil volume, our AA% and our hop addition times are identical.
What might worry you though is that Jamil and John's recipe (which I think uses ProMash) comes up with an IBU figure of 41 while The Calculator comes up with 31 IBUs! BeerSmith comes up with 35 IBUs and Beer Alchemy comes up with 43 IBUs!!!
Unfortunately there is always this discrepancy in IBUs from one program to another. For this reason it is best to use weights rather than IBUs when doing the conversions.
Hope that above makes a bit of sense - fingers crossed
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