As you progress as a homebrewer, one of the things you quickly learn that temperature control during the fermentation process is a large contributor to quality of the end product.
As an example, I’ll refer you to one of my larger mistakes. Hopefully it can be a lesson for someone out there on the interweb, because it sure was for me. Three or four years ago, while living in the San Francisco Bay Area, I bought a lager ingredient kit. I did this in October because the outdoor temperatures were cooler, making it easier to maintain proper fermentation temperature. Lager yeast ferments in the 48-55°F range and ale yeast ferments in the 60-72°F range.
So what do you think happened? We had a heat wave during the week after I brewed that batch. It was very hard to maintain the proper temperature. When a lager ferments at higher temperatures, fruity esters are produced. My lager tasted like bananas – yuck. I didn’t let it go to waste, though, I drank it all… slowly.
Here in Colorado the reverse is the problem. A blizzard went through our general area last weekend and it is very cold. I’m fermenting an ale right now. As tempting as it is to keep our house at the correct toasty temperature, my wallet says “no”.
Enter my mini-water bath. This is the bottom half of a plastic 55 gallon barrel. The top half became my chicken plucker. I put the fermenter in and fill with 68°F water. It will maintain the temperature all day and into the night. When I wake up in the morning, the temp has fallen to 64°F. I use a 2 Quart saucepan and dip some of the water out and boil it and them dump it back in. Usually two pans of boiled water bring it back to 68°F and hold it there until the following morning.
Courtney thinks I’m crazy and overdoing it. We’ll see – the proof will be in the pint-glass soon enough.