In my basement, I decided on an area near the sump pump well, to deal with any condensation that may drip off of the A/C unit. I took an old Amana 6k BTU A/C unit, tore it apart, cleaned it, and rewired it to remove the thermostat. Other than an on/off switch, it's now a dumb unit and runs when it has power.
I built a 4' x 8' x 4' framed box, with two access doors and full internal insulation. All sides and the top are insulated, including from the floor. Expanding foam was then shot into every crack and crevice to make things as airtight as possible. Both doors are tightly gasketed with stick-on weather strip.
There's a temperature probe inside the chamber, and a 25A relay (eBay) controlling the A/C unit.
Right now, the entire chamber is one volume of air, and one temperature. The BCS program looks as follows:
- 0: Compressor Wait. Exit Condition: timer0 <= 0. timer0 is a 15:00 timer. Goto 1.
- 1: Hold. Exit Condition: temp0 >= 44. Goto 2.
- 2: Cool. Assert out0 (A/C compressor). Exit Condition: temp0 <= 40. Goto 0.
As is, with only ~8 gallons of beer stored in it, it is able to maintain 42f (23f < Ambient) by running the compressor for two minutes every twenty minutes. I'm very pleased.
The chamber is so large, because soon it will be upgraded. I am installing a movable gasketed internal wall to divide the space. The refrigeration cell will then be smaller, and I will have a fermentation/lagering/aging cell as well. The movable wall will have computer fans in it, which the BCS will control to exchange air with the refrigeration cell. Thereby allowing me to have a chamber that is both < Ambient, and > Refrigerator. The ferment chamber will be equipped with 3 thermistors. One to monitor air temp, and two more to drop in thermowells in active fermentors. The fermentors (Sanke kegs) will be equipped with electric blankets, which the BCS will independently control. In this way, I can theoretically ferment 20 gallons of beer at once, while maintaining +/- 1f temperature control, per fermenter. They can even have different set temps at the same time.
The main purpose of this design was to kill three birds with one stone (BCS) and also require only one cooling source (window A/C) for the entire process.
Thoughts/questions appreciated! Here's some pictures: