Hot-Weather Wort Cooling
Many brewers, such as our Fearless Leader, do not brew in the summer. Heat is one of the main reasons. Some that brew outside don’t want sweat dripping into the wort. But the bigger issue is the tap water temperature, which is 70 degrees or higher in the summer. This causes problems in getting the wort temperature down to the appropriate pitching temperature. Generally, you can only cool your wort down to about 10° F degrees above the temperature of your tap water. These temperatures are high even if you are brewing Belgian Ales such as a Saison, or Weizen beer. A rule of thumb is that your pitching temperature should be around 4 degrees lower than you target fermentation temperature. When brewing these beers I want my wort to be around 68 degrees then let temperature naturally rise into the 70s from the heat caused by fermentation. There are a variety of methods that you can employ to cool yourwort and help you become more fearless than our Fearless Leader.
Ice Bath: After cooling the wort by water bath or chiller, fill your fermenter with the wort. Put the fermenter into a keg tub or other water tight larger enough container. Fill the space between the container and fermenter with ice. Run water into the container, avoiding getting water into the wort, until the fermenter is about to float. Sterilize a thermometer and measure the wort temperature. Swirling the ice around the fermenter will help bring the temperature down. Once you have achieved your pitching temperature, remove the fermenter, aerate and pitch the yeast.
Pre-Chiller: Many homebrewers use a wort chiller to cool their wort. By adding a pre-chiller in line with the wort chiller you can cool your wort down to a lower temperature. The pre-chiller is an immersion chiller put in line between the water source and the wort chiller, and is submersed in ice water bath. The water flowing from the faucet is first cooled in the ice water bath, and then flows through the wort chiller. If using an immersion chiller it is suggested that you first cool your wort for 10 mintues or so before you put the pre-chiller in the ice-bath. If using a counter-flow chiller, have the pre-chiller in the ice bath at the very beginning.
The Texas Method: Dean Fikar of Fort Worth, Texas pumps ice water through his chiller. He puts a submersible pump into a cooler with just enough water to prime the pump. He then loads the cooler with ice and pumps the cold water through the chiller. The outflow from the chiller is directed back into the cooler so that he does not have to constantly add water. However, when the ice melts he has to drain the cooler and restock it with ice if necessary.
The Stevens Method: Robert built a variation of the pre-chiller method. His method requires two counter flow chillers, a pump, and a 10 gallon cooler. Robert fills the cooler with ice water. He pumps the ice water through the first chiller while tap water counter flows through the first chiller. This process chills the tap water. The tap water continually fills the cooler and he adds ice as needed. The chilled water then flows to the second chiller which cools the hot wort. Like other processes in home brewing, cooling methods span between low tech and high tech. Regardless of your choice, employing an extra cooling step opens the doors to brewing quality beer no matter how hot it is outside.
Make Me Sweat! Cool Tips for Hot-Weather Brewing, by Chris Colby. Brew Your Own, Summer 2001.
Beat the Heat: A Texas Tale on How to Cool Brews When the Weather’s Hot, by Dean Fikar. Zymurgy,