  The box has to be well insulated to minimize heat loss. I used Dow Tuff-R Commercial polyisocyanurate insulation. 1 3/8" thick on the back and doubled up 1" on all sides. Insulation is glued into place using clamps and boards to hold it till it dries.  A wire is run before the insulation for a Snap-Disc Control positioned in the top chamber. This control will turn the units fan on when it gets hot and shut it down when it cools. I used a Snap-Disc Control from Grainger Stock # 2E245  I found that prepping and assembling the cans took the most time in this project. I went though a couple of can openers which I use to remove the tops of 256 aluminum cans. Washing the cans is easier with the tops off. The cans need to be clean.    |  The unit uses 256 aluminum cans. 16 columns of 16 cans each. A cross piece with holes drilled out will hold the cans in place.  I found that a bread knife works good for cutting foam insulation. The cross pieces with holes for cans is not fixed yet. The cans are glued to them and then they slide in together. A 4" hole at each end at opposite corners will be the intake and the outtake.  Cross pieces with holes to hold cans is painted flat black. Notice inside layer of double 1" insulation in top and bottom chamber is stepped down to receive insulation panel to totally insulate all sides of chamber other than cross pieces. This is a sealed unit. All seams and corners should be caulked with heat rated silicone or aluminum duct tape to prevent air leakage.  I used a sharp 3/4" wood chisel to pinwheel the bottom of the cans. It take some time and a little technique but you get pretty good at it after a while. The cans are pinwheeled to slow down the air moving through the cans making the air turbulent to gather more heat transfer from the can.    |