Cooling is a critical step in the brewing process. After the boil it is best to cool your wort as quickly as possible to a proper fermentation temperature. Cooling quickly helps to reduce the chance of infection by bacteria, and also helps to precipitate out coagulated proteins, hops and other debris leftover from the boil. After cooling, the wort is transferred to a fermentor where yeast is added and the brew is fermented into beer.
Methods for Cooling
Here are some methods accessible to the homebrewer for cooling your wort quickly:
- Immersion Chiller - The most popular method for intermediate to advanced homebrewers - an immersion chiller is nothing more than a copper coil that can be immersed directly into the brew pot. Cold water from a hose or faucet is then run through the copper tubing to draw away the heat. A properly built immersion chiller can cool 5 gallons of beer from a boil in 10-15 minutes. The picture shown is a two stage immersion chiller that has one coil for the main brewpot and a second coil that is immersed in ice water to prechill the water going into the main coil. This secondary coil increases the temperature difference between the wort and the cooled water flowing through it, which will cool the wort more quickly.
- An Ice Bath - Extract Brewers that boil only a portion of their full beer volume can immerse their pot in an ice bath to cool it. While not nearly as effective as an immersion chiller, an ice bath can be used to cool small volumes of wort to room temperature if one lacks other means.
- Mixing in Cold Water or Ice - Another method used by extract brewers - who typically boil only a portion of their final volume. Here cold water is mixed with the boiled extract to achieve the final volume (usually 5 gallons or 19-20 liters). The obvious disadvantage of mixing in cold water is the possiblity of introducing bacteria from the cold water into the sterile boiled wort.
- Counterflow Chillers - A device used commercially and by more advanced brewers. Here a coil of copper tubing is set within another tube of larger diameter. Cold water is pumped through the outer tube, while the wort is pumped through the inner tube in the opposite direction. These are extremely effective, and allow one to pump directly from the boil tank, through the cooler and into the fermentor in one shot. Some care is needed to properly clean them to avoid buildup of material or bacteria in the tubes.