Controlling Fermentation Temperatures

posted Oct 2, 2012, 11:06 AM by Richard Bryant
By Jeremy Wickham

It's the age old saying that brewers make wort, yeast makes beer. True? In a sense, yes that is totally true. But we can control the yeast by controlling the temperature in which it ferments at. Try ferementing WLP001 at 68 degrees versus 78 degrees and see what you'll get. Two totally different beers. One being clean and the other having fusel alcohols and acetaldehyde (funky off flavors you don't want in your beer).  That isn't what you were trying accomplish after that four hour brew day was it? In my opnion, yeast and controlling the ferementation temperature is the most important aspect of brewing. There are many ways you can control your fermentation temperature. I'll discuss in short a few ways you can control your fermentation temperatures.  I would highly recommend finding ways to control your fermentation temperatures before making the move to all grain or building one of those professional systems. It is a must for making great beer.

Swamp Cooler


The cheapeast way to control the temperature is by using the old fashion swamp cooler. Put your carboy in a large bucket, throw a t-shirt over that bad boy and drop a little water into that bucket and point a fan to it to help wick the moisture up the t-shirt and by keeping it cool. The interwebs say that this method could keep your fermenting beer five to ten degrees cooler than ambient temps. I used to use this method and even made beers in August, it works, but you have to constantly keep an eye on it. Also you can put frozen water water into the bucket to help keep the water cooler in turn helping keep the fermenting wort cooler as well. Maintaining a constant temperature is pretty difficult, but it can be done and I have done with with this method. 

Son of a Fermentation Chiller


There was a guy in my iPhone programming class that I took in the Spring of 2010 that told me he and his roommate both built one of these things. The image on this one looks mighty fancy. Good ole Google image search right there! But the idea of this is that the larger compartment of this box holds your carboy. You have a thermostat that controlls the computer fan. The fan draws cold air from the smaller chambers in the back. The smaller chambers in the back is actually holding frozen gallon water jugs. It will pull the cool air from the smaller chambers to the larger chambers and just moving cold air. Compare this to a refrigerator or a chest freezer and you'll be saving quite a bit of money. You'll need to be a bit crafty to build one of these things. I'm not too crafty, but I believe I could build one of these with maybe only three trips to Lowes. You also need to maintain the ice jugs as well. So there still maintenance to be done with this option.


Refrigerator or Chest Freezer



I call this route the mecca of fermenation temperature control. It is by far the easiest method, maintenance wise. Set it and forget it. BUT you will pay up front for this equipment. You may can scoop an old refrigerator or chest freezer from the classifieds or craigslist, or even talk your mom into hurrying up and buying that upright freezer she's been wanting and taking her old chest freezer like I did. Either way, there is a lot of up front costs. Then you have to buy the temperature controller which range from $50-$100. I paid around $90 dor my Ranco and I must say it is pretty easy to use. The downfall in buying/acquiring a chest freezer is lifting that full six gallon carboy up and into the chamber. I break a sweat everytime, even in the winter. This has been my best option as far as keeping my fermentation temps under control. There is one downfall I have found by using this method. By orders, my chest freezer must stay outside. So in the winter doing an ale may be a challenge. So I may need to buy a brew belt to actually keep my ales warm enough during fermentation. Who'd thunk that?

Maybe the next time fermentation temperature control comes up, we can get a bit more scientific, but these are just some ways to control your fermentation temperature. Which I could have just said go Google fermentation temperature control and you "may" find some of the same things that I have talked about. I just borrowed them for this quick article.
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