The summer heat is finally here and while most of us love the longer days and time spent outdoors, it becomes a problem for homebrewers that are trying to ferment their beer in a specific temperature range well below HOT. If you’ve got so much money that keeping your house at a yeast-approved temperature of 68 degrees 24/7 isn’t an issue, then this blog post may not be for you. However, for the rest of us, there’s a cheap technique you can use to keep your yeast cool when the days are long and hot.
Like most people, yeast are happiest when they are in a nice comfortable temperature range. Fermenting at too high of a temperature can produce a bad effect in your beer or wine, causing faster fermentataion and producing more esters, off flavors and possibly fusel alcohols. It is also important to note here that fermentations that are too warm are more hospitable to the growth of unwanted microorganisms. This could result in complete spoilage.
Before you can control the temperature range of your fermentation, you need to know what range your particular yeast likes to ferment at. The best way to figure this out is to go to the company’s web site for the yeast you have. For example, if you’re using Safale-04, you can go and get the product guide for it. This tells you that the reccomended temperature range is 15C – 24C (59F – 75F). However, if you are using Wyeast’s American Lager yeast (2035), the termperature range is 9C – 14C (48F – 57F).
Now that we know the temperature range, we’ll pick a temperature to target. If we’re using Safale-04, that temperature might be 68F (a good average of 59F – 75F). Obviously we can’t keep our living space that cool in the summer. Some people use the trick of filling a bathtub with water and putting the fermenter into it. That is a lot of weight for your house or apartment to support though, and makes it tough for anyone to actually use the bathtub. A better solution is to use a round plastic bucket, available at any Target for around $10. Fill it halfway with water at 68F and put the fermenter inside it. Unlike a bathtub, you can keep this anywhere; your garage, your bathroom, your deck, etc. The temperature of the water surrounding the fermenter will not change very much relative to the change in air temperature, which makes for a much more stable environment for your fermenter.
However, we must still keep the temperature of the surrounding water cool. To do this, take two bottles of bottled water (about 20 ounces each), drink some off of each, and put them in the freezer overnight. In the morning, simply put them in the water in the bucket. They will melt very slowly and will keep the temperature steady during the day. At night, put them back in the freezer. Depending on the temperature that you need to keep your fermentation, you can vary the number of freezer bottles you are using. Remember to check the temperature of the water every day to make sure it’s where you want it.
Good luck with your summertime fermenting!