I decided to locate the fridge on the opposite side of the building from the “kitchen stove.” Being only 20 feet wide, this was not a great distance, but made more sense than putting it right beside the stove. The southwest corner was least desirable, and the “cooler box” and stove should have been switched. I plan to swap their locations in the final plan across the road. A lesson learned!
So, in the rear western corner, I built a wall four feet long and positioned it forty inches from, and parallel to, the rear wall, attached to the west wall. An interior door was installed, the cool side insulated with ½ inch closed cell foam having a 4.2 R-value. Plans were to double the foam in the future. The six inch wall cavities were filled with the same foam board cut to fit, then R-19 faced fiberglass was used on top of the foam, yielding a 23.2 total R-value. A length of pipe insulation was cut lengthwise and affixed to the bottom of the door to serve as a threshold seal. We now have a “cooler box.”
What appliance do we need to use? Because of the high run time, I chose an ultra-efficient 12 volt Novacool 4.3 cubic foot model, purchased from Backwoods Solar Electric Systems. When it arrived, I perused the instructions, which discussed adding extra insulation. What a novel idea! I had never thought about that. As per the “dummy sheet,” I removed the screws attaching the condenser coil, to loosen it and pull it away from the rear of the box just enough to add 3 inches of extra foam insulation. There was not room for more. The compressor chassis was loosened, to install 2 inches of foam around it. The top, bottom, and sides got 6 inches added, with 3 inches applied to the door. I was amazed at how easy the operation was, and this can be done to any fridge. In the future, I will do this to any refrigerator I use!
I next built a shelf inside the box, on which to set the fridge. The shelf was located thirty-seven inches off the floor, spanned the width of the entire cooler box, depth matching the fridge. The extra-insulated fridge was placed on the shelf with the rear against the west wall, the left side against the south wall. Before placement, I cut rectangular holes in the west wall at the fridge’s rear, then installed foundation vents upside down on the exterior wall. This would allow the compressor section to vent heat to the outside, and prevent heat build-up inside the cooler box. After the fridge was placed on the shelf, the left front side, right rear side, and top were caulked to block compressor heat from entering the box. The fridge door was configured to open from right to left.
Lastly, I inserted a one-and-one half inch pvc pipe into the rear wall, as high as possible, to serve as a vent for the entire box. A valve was included in the pipe, inside the cooler box, to open and close with the seasons. In summer, the valve remains closed. In winter, the valve is opened to allow cool air in. This uses outside air to keep the box at minimum temperature.
Finally, after all this planning and work, we have an ultra-efficient refrigeration capability. The set-up has resulted in a fridge run-time, or duty cycle, of about 20%. Using 12 volts, and only running 20% of the time, the resulting electrical need has been minimal. Everything still works as well as the day of installation, requiring no maintenance or repairs to date, which has left plenty of time to reuse and recycle any and everything!