Hey macabra11, cool to see another Boise Brewer around here! I'm guessing this Kölsch will be entered in the Treasure Valley Organic Homebrew Challenge? I brewed my entry a few weeks ago - currently lagering in my keezer.
Are you going to brew at the Boise Big Brew site on Saturday? We'll be brewing at the Sockeye brewery, and I think the brewery is going to brew ~400 gallons to help boost our numbers
. The Boise Brewers have a meeting Thursday night at the Front Door, downtown. It's a small group. We'll be talking about the Big Brew recipes, and I'm going to bring a sample of my Breakfast Stout, and maybe the Orange Honey Hefe.
Saturday I'll be brewing the Saison Du Mont on my Ghetto Fabulous HERMS rig at the Big Brew site.
To address some of your questions...
Efficiency - It can be hard to tell exactly. I calculate my efficiency based on what I collect pre-boil. You really need to know exactly how much water you used at strike & sparge - as well as how much wort you collected to know the efficiency you got. You will lose water getting soaked up by the grist, and you will lose water in the dead space of your lauter tun. Then your boil-off rate can vary based on a lot of factors... and it's hard to know exacly how much unfermented wort you lost in the bottom of your boil kettle with the cold break and hops and such. My goal has always just been to know a ballpark to use for adjusting recipes, then compensate in the boil for slight fluctuations. I've done 9 A.G. batches in the past 4 months and I do better each time hitting my numbers.
Chilling with an IC - I've never tried to cool to 60F with my IC straight from the boil. I usually take it down to about 75F with my 30' copper IC. The tap water here has been about 50F for each batch I've cooled, and I can typically get 5.5-6 gallons down from boiling to 75 in about 15 minutes. I stir the cooling wort with my IC the entire time - drastically speeds it up. I also don't run a really high flow rate though the hose, maybe 2 gallons/minute. Once I hit 75 I whirlpool the sh*t out of it with a sanitized spoon, and let it sit for 20-30 minutes. Gives time for some of the cold break and other debris to settle in the center of the kettle before draining it to the fermenter. By then it is usually about 70F and I pitch my yeast.