Converting A Chest Freezer
Susanna and I have been brewing for about a year now. We’ve been having a great time with it, and have made about 14 different batches. Some better than others, but so far, all drinkable (and some have been really good). A few months ago we got a chest freezer from Susanna’s parents’ neighbor. Originally we have wanted one to store summer’s harvest, which we still plan to do, but we realized we could use it as a temperature control for lagers over the summer.
The problem is a freezer’s max temperature is something like 20°F and we needed to keep it at around 40°F. You can buy temperature controls which cycle the power on and off to maintain a higher temperature, but we thought we could do it for free. One website showed us that there are two screws which control temperature, a coarse adjustment screw and a fine adjustment. The fine adjustment is the obvious one with numbers on it 1-10 for instance.
But, if you take apart some of the housing, you can see a tiny coarse adjustment screw. Tightening the coarse adjustment screw will allow the freezer to get to a higher temperature. The physics are explained here: http://www.homebrewtalk.com/f51/guide-set-internal-chest-freezer-thermostat-32f-eliminate-external-control-249612/
With a good amount of trail and error, I’ve gotten the freezer at a consistent 39-42°F. This is perfect for lagers and, as it turns out a keg.