Controlling fermentation temperature can be difficult for the homebrewer. It can be space, time, and money consuming. But homebrewers are a resourceful bunch and many different approaches have been taken to keep temperatures in the yeast's comfort zone.
I've read about a damp t-shirt over the carboy to utilize the cooling effects of evaporation and about the
Fermentation Chiller and its many variations. If you have the space and the resources, using a temperature controller with refrigerator or freezer is going to be the most consistent option. When I found out that I had access to a small chest freezer I started shopping around for a temperature controller.
Many of the commercially available controllers are single stage (cool only) which should be fine if you are fermenting in your house. But if you ferment in your basement or garage you may need to heat as well. I was intrigued by a two phase controller that I saw at my local homebrew store (
Rebel Brewing) and with a little web surfing came across a lengthy DYI thread at
Homebrewtalk. Inspired by the success stories in the thread I decided to try my hand at building my own controller.
Using the resources in the
Homebrewtalk thread I put together a game plan for my build. I drew up a wiring diagram based on a combination of the many examples there. The only difference in the diagram above and the final product is the fuse location. I moved it past the split in the hot circuit so that it is only protecting the controller's electronics.
The controller unit itself is made for aquarium use and was found readily available on Ebay (search for
STC-1000). The other components (outlet, indicator lamps, fuse holders, project box, etc.) were picked up from
Allied Electronics and
MCM Electronics. I had plenty of 14 gauge wire in my shop for the hot and neutral wiring but picked up some colored wiring at Home Depot.
I laid out the project on the computer to check out potential fit problems and used that printed layout to locate the cuts to be made on the project box. The round cuts (power cord, fuse holder, and indicator lamps) were made on the drill press with appropriately sized forstner bits. The rectangular openings for the STC-1000 and the power outlets were made with a rotozip tool. Word of warning with the rotozip, knock the hole out as soon as you finish cutting. The plastic gets quite hot and will fuse back together. I'm sure there are better methods but this worked well with the available tools. It did require a little cleanup around the edges, but a file took care of the task easily.
After all of the cuts were made, all of the components were test fitted. Test fitting confirmed that the layout would work (although it was snug at the heat side outlet). I then soldered all of the connections that could be made before assembly (the connections to the STC-1000 use set screws) and began assembling the back side of the box. The outlets were designed to be clipped in but the project box was too thick for the clips so I improvised by trimming the clips and gluing the outlets in place. The power cord was secured with rubber grommets.
Since the STC-1000 reads in celsius I wanted a chart to put on the top of the box. In Excel I put together a C° to F° conversion chart using conditional formatting to shade the temperatures. I added the basic instructions, my logo, and some other labeling and printed it on a full sheet label. I scratched it up a bit on final assembly but I'm still pleased with the final result.
Thanks to the pre-wiring final assembly went very smoothly. I took it into the house and plugged up the kids' nightlights to test it. Warming the temp sensor in my hand activated the cooling circuit. Test 1 was a success. Application of an ice pack to the temp sensor activated the heat circuit. Test 2 was a success. Everything works!!!!
I would do a few things different, maybe tinker with the layout. Shipping for the components made this a more expensive project than it maybe could have been, but running around town and picking up parts costs gas money and time so it is probably a wash and I still saved $30-$40 over the commercially available version and had a great time building it.
Now to get that freezer...
