Originally Posted by loopmd
My last batch, I just cooked 2 gallons of wort, but it in my primary with 7lbs of ice and topped it off to the 5 gallon mark with cold tap water. Instantly, the temp went down to 70 and I was able to pitch my yeast within minutes. In the past, I have cooked the 2 gallons of wort and put it in my primary without adding the ice, topped everything off with the water and had to immurse the whole shebang in a tub of cold water until I got it down far enough to pitch my yeast. Took a long time. I liked adding the ice, and so far, so good. I racked to my secondary last weekend and it is clearing up just fine.
I just followed a similar process after receiving some advice from the guy at my local home brew store. I made 3.5 gallons of wort. Before putting it in my primary I added some purchased ice to the bucket so the wort would begin cooling instantly (not a lot, maybe up to the 1/2 gallon mark). In my area, bagged ice that you buy at the store must be filtered first, so I wasn't too worried about contamination. Once the ice melted, I mixed it well and checked the OG so that I knew how much more volume I could add. I added a little more ice, let it melt, mixed it well, checked the OG. Repeat. Once I reached the appropriate OG (less than 10 minutes), I checked the temperature and it had already dropped from boiling to about 82 degrees. Almost there in less than 10 minutes! After that, I wanted to continue fast chilling the wort without adding anymore volume that would throw off my OG (volume wise I was just under 5 gal), so I put some ice in a large baggie, sealed it, and put it in the bucket, holding it down and stirring it around for about another 3-5 minutes. By then I was at 78 degrees and was good to go. So I took 3.5 gallons boiling to around 5 gallons at 78 degrees in less than 15 minutes without a chiller. I was thrilled!
My advice would be to not add an entire bag of ice all at once. Remember that ice will change in volume as it melts to water.