A bit off the subject as no bd or wvo is used but it is still a non standard way of heating. I am interested if any of you out there have built a solar box heater. Youtube is full of vids of the type I am talking about and most us aluminumn beverage cans to gathere heat. I am interested in using alum. window screen instead. Any input?
I saw that beer can idea weeks ago and love it!!! I'm going to be working on something very similar this fall...
What's the idea with the window screen? I don't understand...
The window screen serves the same purpose as the cans, adsorb heat, BUT I think the cans do a bit better job because they force the air to move thru heated channels to gain more heat. I am working on one of each in a small scale to do some testing. The screen unit would be faster to build.
I am going to have to build a triangular box for my south wall so I can get it right up by the roof because of a building next door blocking the lower light.
I'm still confused. How would screen be formed to contain or adsorb heat? The cans work by providing fairly efficient (dirt cheap) means of heat transfer to a small pockets of air and slowing natural convection.
I had to check this out. So the idea is like this one?
MAN! I just took in all of my aluminum cans to the scrap yard!
Yep Ryan, like that. As for the screen, all it does is store a bit of heat just as a can would. More than one layer of screen would be the idea and it could be convoluted like roofing to allow more surface area. The heat stored is then transfered to the air passing thru. I plan to use fans instead of convection. I am talking about metal window screen painted black. When I get my test boxes done I'll report on what I find in temps for the two systems.
I have known about commercial units like this for a long time but the cost put me off. Then I started seeing the can idea units and how cheap they can be made. Plus no one makes a triangle shape which is what I need on one place. A standard shape will do just great for warming up a East facing bedroom that is always cold in the AM.
I hope you prove me wrong but I think your window screen idea is going to fail.
1. Heat transfer with the tiny wires is going to be poor because they are so tiny. The screen idea is a double edge sword in this respect. Lots of surface area to soak up heat but also minimal transfer area.
2. With the beer cans, the heat is transfered into the internal surface which is isolated from the rest of the unit. Air flows through the insides of the can and once heated, never see's a cold surface. With your screen idea, (as I understand it), the screen is going to heat the air up inside the unit as a whole.. (no channels).. but as the warm air moves around the inside, it will contact the cold glass and that's going to cool it back down again.
Or am I misunderstanding your application of the screen?
I think you are correct Murphy, not my idea but just one version I have seen on the web. I am only interested it it because I don't get anything in beverage cans and would have to go around begging cans. Plus and proably the most important to me is there is much less labor involved in making the heater. I have seen one that just uses baffles to snake the air back and forth as it travels up the inside.
The best idea I've seen so far is one guy who used expandable flexible aluminum clothes dryer ducting. It's cheap and has tiny ridges all over it that greatly increase surface area. It's also easy because its one piece up to six or eight feet long.
Got a 3x3 box for a test bed, got some cans, going to divide the box and do a side by side test once I get it insulated and find a cover for it. Two small 12 volt muffin fans to move air. I also have been thinking about how thin sheets of aluminumn stacked and seperated might work.
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