This is my version of a converted freezer that I
use to maintain proper temperature control for fermentation and serving of my
homebrews. This project started out as a 10.5 cu. ft. freezer. It now has two
chambers, one hold a fermentation container, the other holds up to four
Corny kegs. It currently has two taps to serve my homebrew with
room to add two more. While fermenting a batch of homebrew, the fermentation
chamber temperature is closely controlled by an add-on temperature controller.
During these times, the serving side maintains a 10 to 15°F lower temperature.
When not fermenting, the controller is set to maintain a 40°F temperature in
I started out with a typical chest freezer and purchased a FermTemp temperature controller from Brewer's Resource . The freezer's controller is set to maximum cooling (My freezer maintained a 0°F temperature at this setting) and the external controller uses feedback from it's thermocouple located inside the freezer to either turn on power to the freezer or to turn power on to a heater also located inside the freezer. The heater was made from a typical electrical junction box, ceramic light bulb base, electrical cord, and a ceramic reptile heater available from pet supply stores. I placed the heater in the fermentation chamber. Note: If you live in a cold climate like I do (Portland, OR) and keep your freezer/fridge in a non-heated area like a garage, an internal heater will be necessary to maintain temperatures above that in the surrounding room.
Now I didn't want to drill holes in the nice freezer so I decided to add a collar made from cedar 2x4's. Cedar resists mildew and is moisture resistant. I can't hammer a nail straight to save my life so I was pleased with the appearance of the final unit. First, off came the lid. The 2x4's were measured and cut to match the outer dimensions of the freezer. Since the lid has enough weight to topple the 2x4 frame and not wanting to drill any holes in my freezer, I measured and cut 1" x 10" cedar plank to surround the 2x4 collar on the two sides and the front. It extends down below the collar and snugly fits the freezer. The back piece started out as a 1"x 10" but the upper 5" broke off when I was trying to cut out the slots for the lid hinges (read as "too weak"). I used a 1" x 4" piece on the back. The collar fit over the upper lip of the freezer. I bought longer screws that had the same thread as the hinge screws and secured the back panel to the nuts used for the freezer lid. This is the only place that the collar is secured to the freezer.
The lid was set on the collar, each hinge was held down in place and the holes for the new hinge location were marked on the back 2x4 (mark the holes about1/8" lower than where the hinge comes to rest to force the lid seal to compress against the 2x4 when closed). Attach the lid and your done with the collar.
Future modifications for the collar include some type of seal or sealant between the collar and the top lip of the freezer, galvanized sheeting along the top of the 2x4 to improve the seal between the collar and the lid,and maybe a nice coat of varnish.
To separate the fermentation chamber from the serving chamber, I picked up some foamed polystyrene (PS) board at the local hardware store. I cut it to size and used the interference fit to maintain its position in the freezer. By placing the thermocouple and the heater in the fermentation chamber, the temperature of fermentation is controlled to within + 3°F. The serving side sees cooling whenever the fermentation chamber sees cooling. However, the insulator board keeps the heat on the fermentation side. Hence, I have found a natural 10 to 15°F lower temperature in the serving side. Moving the insulator board one direction or the other changes the dimensions nicely for the chambers. Adjust to your own requirements.
Future modifications to the chambers include creating a better seal between the insulator board and the lid to minimize the heat that goes from the fermentation side to the serving side. Since heat rises and that's where the poor seal is, I suspect I can get another 5°F differential. I am also looking into adding another controller to maintain the serving side temp only and then using my current controller to handle heating and cooling of the fermentation chamber. The cooling circuit would then be hooked up to a fan mounted in the insulator board to bring cold air from the serving side.
While the collar nicely adds 31/2" to the internal height of the freezer which allows me to put my fermentation bucket on the internal shelf, it also allows me to mount a multitude of things onto and through the 2x4's. Note the CO2 distribution manifold and the through taps. Future modifications include installing connectors for the controller(s) heater, fan and thermocouple.