Making great beer is all about nurturing your yeast. It doesn’t matter whether you live in the sultry heat of Louisiana, the frigid depths of Alaska, or anywhere in between, temperature extremes and variability make for unhappy, stressed-out yeast, and that leads to off-flavors and stuck fermentations. Some styles may even be impossible to brew au naturel in your climate. Many homebrewers do their best to work around this by brewing seasonally or fermenting in an interior room less affected by the weather, but lagers are beyond their reach, and daily temperature swings can sabotage even their most dependable recipe. Fortunately, technology can give us the environmental control we need.
Professional brewers manage temperature with glycol-jacketed tanks, but that doesn’t really scale down economically to 5-gallon batch sizes. Instead, the homebrewing solution is usually to build some kind of temperature-controlled fermentation chamber. The easiest approach is to repurpose a refrigerator and use a simple, single-stage thermostat with a sensor and an outlet. The advantage of using a refrigerator is that it’s already pre-built to insulate and cool things down. The setup is simple—plug in the fridge and place the sensor inside. Then all you need to do is set the target temperature, and you’re ready for lagers or you can just ignore that summer heat wave.
The next step up is to expand on that basic idea. Replacing the refrigerator with a chest freezer and moving to a dual-stage controller puts every style at your fingertips. A chest freezer does cost a little more and takes up a bigger footprint, but a fifteen-cubic-foot freezer has room for five or six carboys, and the temperature stays steadier when you open it. That’s very convenient, but the dual-stage controller is the powerful part of this upgrade. A single-stage controller is locked into one action: when things get too warm, it turns the refrigeration on to chill things down to the target, and once that’s reached, it turns the refrigeration back off. A dual-stage controller works both sides of the target temperature. When things are too hot, the cooling side kicks in, but it also has a warming side for when it’s too cool. The fridge or freezer is plugged into the cooling side, to work just like the single-stage configuration, and a heat source such as a heating mat or warming jacket is plugged into the other side. The combination makes it possible to brew lagers in August and saisons in February.
My current setup is a 21-cubic-foot chest freezer that I found used on CraigsList. I fitted it out with a Love Series TSS2 dual-stage controller. Putting these two together was fairly involved, because the controller doesn’t come pre-wired. I needed to do some electrical work to connect it to a power plug on the one side and then wire a pair of power outlets for heating and cooling circuits. I also had to cut a hole in the lid of my freezer to mount it. It was worth the effort, though, with a digital readout and support for programming the target temperature range along with sensitivity. On the other hand, if you’re not as comfortable playing electrician, I’d recommend spending the extra money for a pre-wired controller such as the Auber Instruments TD100A or the Ranco dual-stage wired controller.
Once you’ve set up your fermentation chamber, it’s good to understand a little bit about thermal mass. In particular, you should know that the air temperature fluctuates much more than your beer will. Placing your sensor either in your fermentor or in a bucket of water (make sure the sensor supports this) will keep the controller from waffling as much. Similarly, filling up the empty space in your freezer with water-filled carboys will act as a bigger thermal mass and hold the temperature steadier. A final tip for converted chest freezers is that it’s a good idea to keep your fermentors inside a second bucket. This can catch any blow off and it makes it easier to lift the carboys in and out.
Now you’re ready to tackle any style, regardless of the weather, knowing your yeast cells will reward you for giving them a comfortable place to work.