frankvw
Well-Known Member
I'm sure I'm overlooking something obvious, but I just can't see it...
I'm trying to calculate a few recipes for a stove-top partial boil in small pots. Instead of boiling 3kg of malt extract topped up to 15 liters, I want to boil 1kg of malt extract topped up to 5 liters, then add the remaining 2kg of malt extract post-boil and then top up to 15 liters when transferring the wort to the fermenter.
As far as I understand it (please correct me if I'm wrong) my hop utilization should be roughly the same, since the wort gravity is the same. In fact, Palmer & Zainasheff ("Brewing Classic Styles, p.35) state that converting a recipe from full to partial boil amounts to boiling all the hops with half the malt extract in half the water. I'm using a 33% boil volume instead of 50% but as log as the boil gravity is the same (which it is) this should not matter significantly (within reasonable limits, of course).
But when I run this through Beersmith, everything starts to go sideways when I change my equipment volume from a 5 gallon / 19L pot to a 2 gallon / 7.6L pot (using the pre-set equipment profiles). Suddenly my preboil gravity is more than 1.100 and my hop utilization takes a complete nosedive (15 grams of 11%AA bittering hops boiled for 60 mins gives me 4.1 IBU's).
So... What is the proper way to calculate a recipe (OG, IBU's, color etc.) in Beersmith for partial boils? Also, what is the relationship between boil volume and hop utilization (in real life and as far as Beersmith is concerned)?
I'm trying to calculate a few recipes for a stove-top partial boil in small pots. Instead of boiling 3kg of malt extract topped up to 15 liters, I want to boil 1kg of malt extract topped up to 5 liters, then add the remaining 2kg of malt extract post-boil and then top up to 15 liters when transferring the wort to the fermenter.
As far as I understand it (please correct me if I'm wrong) my hop utilization should be roughly the same, since the wort gravity is the same. In fact, Palmer & Zainasheff ("Brewing Classic Styles, p.35) state that converting a recipe from full to partial boil amounts to boiling all the hops with half the malt extract in half the water. I'm using a 33% boil volume instead of 50% but as log as the boil gravity is the same (which it is) this should not matter significantly (within reasonable limits, of course).
But when I run this through Beersmith, everything starts to go sideways when I change my equipment volume from a 5 gallon / 19L pot to a 2 gallon / 7.6L pot (using the pre-set equipment profiles). Suddenly my preboil gravity is more than 1.100 and my hop utilization takes a complete nosedive (15 grams of 11%AA bittering hops boiled for 60 mins gives me 4.1 IBU's).
So... What is the proper way to calculate a recipe (OG, IBU's, color etc.) in Beersmith for partial boils? Also, what is the relationship between boil volume and hop utilization (in real life and as far as Beersmith is concerned)?