I am no expert on fermentation. I have at least 10 batches of beer and one batch of apfelwein under my belt so take this advice for what it is worth.
One of the single most important things you can do for your fermented drink is to control the temperature of fermentation. Why is this important?
If you ferment at too high a temperature, your yeast will produce "off" flavors in your drink. If you ferment too low (not likely to be a problem for most), you could get a stuck fermentation. A stuck fermentation is when the yeast go dormant and stop eating the sugars. I will use my beer batches as an example of what a difference fermentation temperatures make.
January of last year I made a simple Muntons Gold Pilsner kit. You mix prehopped malt extract syrup in boiled water and ferment. Done. Well... The instructions said to ferment at around 70 degrees Fahrenheit, so I put the fermenter in my upstairs bathtub and shut the door to the bathroom so it would stay warm. It was winter and I was thinking staying warm to keep the yeast active was the thing to do. WRONG. It was 70 in the bathroom all right, but the fermenter got warmer than 70 due to the exothermic process of fermentation. The fermenter probably got up to 80 degrees. The resulting pilsner was undrinkable. I kegged it and let it sit for months. It never got better so I tossed it.
The next beer the wife forced me to put in the basement so we didn't look redneck to the cleaning lady.
That next batch of beer and the several following were WONDERFUL. The next several batches of beer were all produced during the winter. Then, spring came. I wanted a lawnmower beer so I made one in June. It was ready by the end of July for party a I was having. I noticed in this batch of beer it had the same nasty off flavor the pilsner had. That's when it hit me. The basement was warmer and the fermenter got too warm again. The winter brews had fermented in a 60 degree room in the winter while the lawnmower beer was in a 68 degree room for the summer.
I figured I had two options. 1) Only brew in the winter. HA! 2) Make a fermentation chamber to control the temperature of my fermenting beer. I had an old college dorm fridge laying around that I cannibalized for the project. I also had to go buy about 50 bucks worth of materials to make a chamber for the fridge to cool. Now I can brew whenever I want and never have to worry about off flavors from warm fermentations.
Just something for everyone to think about. We have a lot of people in here that are new to brewing. There are a lot of variables to making a good drinkable product. Don't give up if you get something nasty your first couple of times out. Write down what you did then come here or other forums and ask questions. People will want to know what you did and what you fermented at to help diagnose your problem. So it is in your best interest to take notes.
My mom gave me a 4cf mini fridge, so I removed the door and attached it to a box I made out of 2" pink foam board. It's big enough for 3 better bottles, and I use a Johnson Control thermostat to control it.
I can ferment, cold crash or even lager in it. Instead of Better Bottles, I can fit 6 kegs in it.
Mine is big enough for two buckets. I tested it for an hour and it got the chamber down to 42 degrees but I shut it off since it was only a test. Mine happily holds 60 degrees for ales. I'd like to try a lager at some point.
I made mine out of two sheets of the 2" foam insulation from Lowes, my dorm fridge, a love temperature controller with probe, and lots of calk and loctite power grab.
ETA: I also bought a 120mm server fan to circulate the air on the inside of the chamber.
Been really trying to avoid building a ferm chamber. I really only need it during the summer, when the temps get to high.
I need finish up a few other projects...
Although, I can now lager in my keezer. Might do that next summer.