On brewday, chilling your wort as quickly as possible has a lot of benefits. Since it's the last big thing on the brewing schedule, faster chilling means you can finish your brewday more quickly. From a chemistry perspective, faster chilling increases protein coagulation, known as "cold break", which can lead to clearer beer. From a sanitation perspective, the faster you chill your beer and pitch your yeast, the less likely you will get an infection. So it's no surprise that there are numerous methods devised to cool your wort as quickly and efficiently as possible. Here are three of the most common methods for chilling your beer on brewday, with pros, cons, and usage tips.
The ice bath is the least complicated chilling system, and it's the one that most homebrewers start off with. To use an ice bath, fill a large bucket (larger than your brew kettle), sink, or tub with cold water and ice, and simply soak your kettle in it. The more water you use, and the colder water you have, the quicker your wort will chill to fermentation temperatures. I usually fill a few old milk jugs with water and freeze them a few days before brewing. They're faster to make than ice cubes, and they stay frozen longer, too.
The biggest downside of this method is the amount of time it takes to cool the wort. If you're doing small batches (3 gallons), it will take at least an hour to get your wort below 70°F, and that's with adding ice a few times through the process. If you're doing 5 gallon batches, expect it to take a couple hours and a lot of ice. It's helpful to add a very large amount of ice and let it chill overnight. While the process may be low maintenance, the extended chill time may impair beer clarity and increase the risk of infection in your beer.
Pros: Inexpensive (you need a sink, water and ice). No extra cleaning/sanitization required.
Cons: Increased cooling time, leading to risk of infection and chill haze.
An immersion chiller is a good step up from the ice bath for most homebrewers. An immersion chiller is a long coil of copper tube, from 20 to 50 feet, with hoses that can connect to a sink or a yard hose. To chill the beer, immerse the chiller into the wort, and run cold water through the copper until the beer is cooled. The beer begins to cool quickly, from the bottom of the kettle to the top.
When using an immersion chiller, make sure the outside of it is free of debris before you put it in the kettle. Additionally, you should put the chiller into the kettle 10 minutes before the end of the boil to sanitize the outside of the copper. Throughout the chilling, keep the lid on as tightly as possible to prevent air from contaminating the wort.
If your immersion wort chiller fits just inside your kettle without touching the sides and has enough coils, you should be able to chill your beer within a couple degrees of the water temperature within 30 minutes. If your wort chiller is too small for your kettle, it can take up to an hour for the beer to get to the same temperature. In either case, this is a step up in efficiency from the ice bath method.
Pros: Faster chill time. Easy to clean and sanitize. Inexpensive ($50 to $100, depending on size and quality)
Cons: Uses a lot of water. Doesn't scale up if you move to a larger kettle.
Counter Flow Chiller
A counter flow style chiller cools the beer outside of the kettle, before it goes into the fermenter. A coiled copper tube is surrounded by a larger tube, which can be made out of copper or hose. As hot wort flows through the smaller internal tube, cold water flows the opposite direction through the external hose. These "counter flows" cool the wort very efficiently, since cold water is working on a smaller amount of wort at any given time. If the wort and water flows are balanced correctly you can chill the wort to within a couple degrees of the cool water temperature in a single pass through the chiller, which can be as quick as 15 minutes.
The best way to use a counterflow chiller is to pump your wort with a food grade liquid pump that can handle boiling temperatures. Often times the pump is more expensive than the chiller, so this really only works well if you use a pump in your brewing process already. If you're upgrading, expect to spend at least $150 on the chiller and around $200 for a pump and additional hardware.
Sanitation of a counterflow chiller is a bit difficult, since the cooled wort flows through an interior copper coil. The best way to sanitize is to pump boiling worth through the chiller and back into the kettle for the last 10 minutes of the boil. After each use, I like to pump a gallon of near-boiling clean water through the chiller to remove any hop debris or leftover wort from the inside. Even though the counterflow process is a little more complex, it is efficient and the same chiller can work for any size batch of homebrew.
Pros: Uses less water than immersion chiller. Fastest way to chill. Same chiller can be used for 5, 10 or 30 gallon batches.
Cons: Requires pump. Difficult to clean and sanitize. Expensive.
Tell us: what method do you use you chill your wort?
About the author: Joe Postma is a homebrewer who is seeking that perfect blend of creativity and science required to make great beer. He moonlights as a consulting actuary during the week.