Materials List:

1. (2) sheets of 24” x 48” -  ½” or 5/8” thick MDF
2. (1) can of flat black spray paint
3. (1) tube quick dry caulk (your color of preference)
4. (50 Approx.) 2” finishing nails (to go with a finishing nailer)
5. (1) tube Wood glue
6. (100 Approx.) 12 oz. beer or soda cans
7. (2) 12” x 6” pieces of chicken wire
8. (1) 2 3/8” hole saw with pilot bit
9. (1) power drill
10. (1)  37.25” x 25.25” piece of fiberglass – Make sure you let Lowe’s or Home Depot cut this to size. It is difficult to work with and can crack easily!
11. (1) 120 mm, 12 volt computer case fan
12. (1) DC power jack
13. (1) DC transformer – Pick your voltage (6 to 12 – But make sure the transformer is capable of supplying your fan with enough amperage at the given voltage)

Solar Heater Build Procedure:

1. We first have to build an enclosure. Depending on how large you want to make your solar heater, you will have to choose the right dimensions for you. You’re welcome to follow my dimensions as I know that mine work. – The box I made was made from 5/8 MDF found at a local Lowe’s. Thinner MDF will bring the weight down significantly…..I bought 2 sheets that were each 2’ by 4’. One sheet will only have one cut down to 24.0" x 36.0" and will serve as the back board. Cut the other sheet (I highly recommend using a table saw) into the pieces listed below:

1. (2)   36.0  x  6.0”
2. (2)   25.25”  x  6.0”
3. (2)   16.0”  x  5.375”

2. The large piece (24” x 36”) needs to have 2 holes in it at opposite corners (see Picture 1 and 2). The upper hole will have a fan mounted to it so it will have to be the diameter of the fan blades (in my case 120 mm or 4.7 inches in diameter – if you use a different size fan, make sure and measure the diameter of the blades). Make sure the holes are not too close to the edge of the backboard, as the fan will overhang the hole quite a bit. Most likely, you will want to put fan covers on the exterior holes so that things like pets or children do not stick their paws/hands into the box. The mounting holes for the covers will also overhang the holes.

3. You will now have to assemble the pieces as shown in Picture 2. Assembly is easiest if wood glue is placed on all of the joints prior to assembly. Use 2” finishing nails and a finishing nailer using approximately 100 psi air. All boards are nailed to the back board. (See Picture 3)

4. Once assembly is complete, remove any extra dust using some compressed air, and break out the caulking gun. Run a bead of caulk around all of the inside joints of the box.

5. Next we will want to pre-drill for the mounting of the fan and outer protective grills.

6. Painting is up next. Take out your can of flat black spray paint and paint the inside of the box black. Ensure that all surfaces are clean prior to painting, and completely black and covered after painting.

7. Once this is completed, set the box aside. We are going to deal with the cans now. I ended up using approximately 100 soda, beer, etc. 12 oz aluminum cans for my project. You will need more or less depending on where you place your guards to allow free access to the fan and air inlet (we’ll deal with those in step 12).

8. Take each can and remove the tab used to open the product. Using a 2 3/8” hole saw, remove the bottom of each can. This can be difficult – however extremely easy if you can hit the exact center of the bottom of the can with the pilot bit on the hole saw.

9. Painting the cans can be tricky and must be done only after cleaning out all of the aluminum shavings and left over stickiness from the product. I found it was fairly easy to take a garden hose sprayer and spray out each can prior to paining. They will have to dry before continuing on to the next step.

10. Paint the inside of each can, completely covering the bottom and the sides. There is no real need to paint the outside of the can, unless you want to. The sides don’t tend to be very exposed to the sun because of the way the cans are packed into the box.

11. Before we go any further, we need to discuss how the fan is going to be powered. For my project, I found a used 12 volt computer fan, and ran it off of 6 volts to ensure that it didn’t make too much noise or run too fast. There does need to be some residence time inside the box so the air moving through has a chance to absorb some heat before exiting the box. I installed a power jack in the bottom of the box with wires that run up to the fan. (See Picture 4) This makes the unit clean and eliminates wires running everywhere on the outside of the box. Install the fan and outer grills while you are at it. You will also want to go ahead and connect the fan. I used a soldering iron and some heat shrink to ensure a proper connection.

12. Now you can install the guides to keep the cans from interfering with the fan or air inlet. I used chicken wire cut to the depth of the box, bent around and formed, and finally attached using a staple gun (See Picture 5 & 6).

13. It’s time to arrange all of the cans inside of the box. I wouldn’t recommend stuffing the box until it is about to burst as you do want the ability for air to move around freely within the cans as well. Just fill it up.

14. Now for the final step – Mount the plexi-glass sheet to the exterior of the box using a bead of caulk (be generous with this bead to ensure proper sealing). This seems to be the easiest way to both affix and completely seal the box. Using screws will leave air paths, and you also run the risk of cracking the plexi-glass. Make sure to remove the plastic covering from the plexi-glass before application. You are also going to want to make sure that when positioning the plexi-glass, that you do not have the bottom edge of the plexi-glass overhanging the bottom of the box. When you set the box on a window ledge in the sun, you do not want the plexi-glass supporting any of the weight of the box. That’s what the heavy duty MDF wood is for!

15. Wait for the caulk to dry – I would recommend at least 2-3 hours at near room temperature before you move it around. I placed flat, heavy objects around the edges of the plexi-glass while the caulk was drying to ensure good adhesion and proper sealing.

Now point it towards the sun and enjoy the free heat!

Picture 1

Picture 2

Picture 3
 

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Picture 4

Picture 5

Picture 6

Picture 7 - Final