I've been considering starting to prime with gyle, and came across this thread. Thanks for the link Revvy. Seems too simple to be true, so I did some math and I'd like to get feedback on it.
I'm planning to brew a 6 gallon batch of Rye IPA and save a quart (0.25 gallon) of gyle for priming. According to the Gyle Calc, I need 0.9 quarts. My math to check this is below.
OG: 1.080
Volume of Gyle: 0.25 gallons
Points Per Gallon: 0.020
Fermentability: 75% (guess, but seems reasonable)
Priming Points Per Gallon:
0.015
So, to compare this with a method I have used before, I decided to compare to priming with corn sugar.
IPA Volume of CO2: 2 (per
http://www.tastybrew.com/calculators/priming.html)
Corn Sugar to Prime Batch:
3.7 oz (per
http://www.tastybrew.com/calculators/priming.html)
Corn Sugar Points Per Gallon Per Pound: .046 (per
http://www.howtobrew.com/section2/chapter12-4-1.html)
Corn Sugar needed to achieve one gallon of .015 gravity:
5.2 oz
Therefore I'm finding a fairly wide descrepancy between the Gyle Calc and my hand calculations (5.2 oz corn sugar equivalent oz vs. 3.7 oz corn sugar per style guidlines). Any thoughts? Is it because the Gyle calculator doesn't take into accound desired volume of CO2, or is my estimated fermentability somehow off when using to calculate priming doses? Or is my math wrong?