We brew 10 gallon batches. We have a 60ft wort chiller (a wort chiller, for those not in the know, is basically a huge spring made out of hollow copper tubing) that we run hose water through. In theory, this should work really well: big copper rings mean lots of heat-conductive surface area to move heat from the wort into the hose water inside the tubing. We also waste a lot of water in this process -- hose water goes in one side, hot water comes out the other and goes down the sink.
Target temperature for not killing the yeast is 75 degrees Fahrenheit. Our hose water is about 60 degrees. Air temperature this time of year ranges from 60 to 80 degrees.
The first 60 degrees or so go by pretty fast: 10 minutes or thereabouts. It's everything after that. Those great laws of Thermodynamics that get bandied about in so many evolution-creation arguments really work against us here. The rate at which the wort will approach the temperature of the hose water (again, 60 degrees) decays exponentially, such that getting the wort from 100 down to 90 takes approximately 10 minutes. 90 to 80 is another 15 minutes. And those last five degrees? Oh god, they must take DAYS.
So we devised a better system which we will be implementing this week. It saves water AND time. I'll describe the plan carefully, so that you at home can follow along:
- We have a wort chiller. We'll call it WC1. It goes in the boil kettle. It has two ends, the input (where water goes in) and the output.
- We're going to buy a second coil of copper tubing. We'll call it WC2. It goes in a cooler filled with ice water (possibly salted). It has two ends, the input and the output.
- We're going to get a water pump, one of those ones you can buy at a hardware store for $25. Not food grade.
- We take the pump and attach it to the output of WC2 and the input of WC1. We put the output of WC1 in the cooler filled with ice water. WC2 is submerged in the ice water, so its input is is the water.
Flow now looks like this: Cold ice water goes into WC2, is forced through WC1 by the pump, and then returns to the cooler once it's gone through WC1. It's so brilliantly simply. We recycle the water, and at the same time make the water colder. We essentially transfer the heat from the wort into the ice. Combine with a Mythbusters episode that taught us the fastest way to chill beer (and thus chill water) is by submersion in ice water or, better, salted water, and you have a great system that saves time and resources. Excellent.