Another Solar Air Heater Update

     I wish this were the last update on this project, but nothing goes quite the way that it is planned. I have had one heater temporarily installed for the past week with promising results. Temperatures coming out of the vent in the house have ranged between 90°F and 158°F between 10:10am and 4:00pm. I think that the time giving off heat will increase by around an hour by lifting them off the ground as originally planned. There seems to be plenty of sunlight by 9:00am but the current location is still in the shadows. Also, it is shaded by the garage around 4:00. I look forward to installing the scaffolding that will get them around 10 feet higher.     I completed another unit this weekend, but haven't installed it - I want to have the next two installed without doing any temporary ducting. We'll see what the week brings.
     So I guess, it's time for an explanation. After the main structure, insulation, and air channels comes snap-disc sensor (a bi-metal disc that will turn the fan on at 110°F and off at 90°) and the heat transferring surface. The sensor is installed near the top with the wiring exiting out the side running down to the fan. Then, starting at the air intake, I covered the channels with heavy duty kitchen aluminum foil. I fixed it in place with staples, then after getting each piece in place, I went back lining all edges with wire that I stapled in place with an air gun. Well, almost all edges. I missed one and now there is a visible gap in the heating surface.
     Then I placed 1x2 all the way around the outside edge to create another insulating air gap and to get the total depth close enough to the width of my steel studs.      I put the extruded polycarbonate on top, lined the sides with 1" rigid foam and screwed the steel studs to the sides.     Naturally, the second unit turned out a little better than the first, practice makes perfect - I suspect if I build a hundred more of these, I'll be making some amazing heaters...