Winter is almost upon us and those of us in the northern regions will find it slightly more difficult to reach or maintain those fermentation temperatures for ales…especially if you ferment in a basement. There are products out there to help you keep your beer warmer, products like The Brew Belt or The Fermwrap Heater can help keep your ales at the correct temperature. My basement in winter, gets down to the mid 50′s which will be perfect for some lager strains, like San Francisco Lager Yeast. But for ales, that doesn’t work quite as well. I generally prefer fairly clean ales, but I do want some minor estery characters in there. So products like the brew belt or the fermwrap have value for those of us in the north. But they also cost money, and you need place to plug them in. If cost or lack of an outlet in your fermentation area is a problem for you, you can easily employ the solution I use which is free and takes full advantage of natural energy produced by fermentation. That’s right, your fermentation itself produces heat. The yeast consuming sugars also expend energy to do so, and just like when you are working out, they heat up. You can capture that heat and use it to your advantage. Below is a picture of the ambient temperature of my basement in November.
At first glance it may not seem like such a bad deal to ferment at such a cool temperature. You will end up with a very clean, almost lager-like ale right? Well, sure. But if I wanted to produce a lager, I would simply brew a lager. It’s the estery character of ale strains (even clean strains) that bring a bit of character to the beer. While clean strains like the Chico Strain A.K.A. California ale or American Ale strains have a reputation for being clean, they do contribute a very low fruity ester to the beer, less than the English ale strains but more than what you will get with a properly fermented lager. Another concern is that at the lower temperatures, the yeast will not clean up the diacetyl as quickly and efficiently as normal. They may even flocculate before cleanup is complete. So you could end up with a lot of diacetyl if you ferment your ale too cool. You need to be sure that you are in the proper ideal range for the yeast you are using. For example, the yeast I am using today is Wyeast London Ale Yeast (Wyeast 1028) which has an optimum range of 60-72 degrees according to Wyeast. If you are using White Labs WLP013 it lists the range at 66-71 degrees. Any cooler than that and I run into problems. Since both strains are probably similar I want to be in a range that both producers list. Personally, I want to ferment in the mid to upper 60′s with this beer. I want some moderate estery characteristics, but don’t want to exceed the optimum temperature and have excessive esters or fusel alcohols. The solution for me to wrap the fermentor in a thick blanket and capture the natural heat energy produced by fermentation. The amazing part is, how much you can increase the temperature by. Below is a photo of the temperature captured by insulating with a blanket. I should also note that the actual temperature of the wort inside is probably a degree or two warmer, so can adjust how much of the fermentor is exposed to allow some of the heat to freely dissipate.
So you can see that you can boost your temperature by using a blanket as an insulator. The downside is that the temperature control is not as precise as if you connected a brew belt or fermwrap and/or a temperature controller, but if you want to hit a specific range because your air temperature is too cool, you can easily do it for free. I’m sure everyone has a spare blanket lying around somewhere. If you don’t you can also get the same effect by covering the fermentor with a cardboard box slightly bigger than the fermentor itself. It will trap the heat and keep things a little warmer as well. I hope this help some of you in the northern regions produce better ales in the winter. Then again, winter is a great time to produce those lagers without the use of a chest freezer or refrigerator. Happy Brewing my friends!