Does anyone have any good estimates as to what your typical hop acid utilisation rates are in home brew settings? I've seen figures like 35% for start of boil drifting down to 15% for a 2min addition, but that was for a 2 hl pilot brewery. I want to know what my bucket with a kettle element is going to achieve. Any ideas? Is 20% realistic?
What matters most are the vigor of the boil and the elevation that you are brewing at. A whimpy boil may reduce the isomerization, but you only need a boil that visibly and continually roils the wort surface. You don't need to have a rip-roaring boil since that does not increase the isomerization...it only increases the amount of evaporation. The elevation will affect the wort boiling temperature. So if you are located in an area that is 100's of meters above sea level, then the boiling temperature and hop isomerization will be reduced to a degree. The size of the brewing system should not have a huge effect on the isomerization rate. Use one of those brewing calculators to figure out what the ending IBU's might be.