Solar Heating by Air

Build your own solar heater, from some stuffs that you can easily find around the trash.

You can adjust the size of the design according to your needs. In my case, i determined the size of my frame by an old terrace door that I founded. It was 1910x910mm, aluminium frame include.

The Panel is exactly turned to the south in order to get the maximum solar hours as weell as inclinated 52 degrees with the horizontal line. Determining the perfect orientation depends on your location around the world. It tend to be the geographic latitude + 10º and orientation Suth +/- 15% East/West.

In my case, the geographic latitude is 42º (North of Spain) + 10º= 52º and South orientation.

Once instaled, you will be able to get warm air into the room around 30-50º C depending of the amount of solar hours and the amount of air recirculated between the room and the air heater.

And if you like it, please, don't forget to vote for my project to the contest!

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Materials:

1- 132 cans salvaged from the trash

2- Glass panel, old window or door with glass, plexiglass or any plastic sheet transparent

3- Fan, from any old device or any old smoke extractor

4- Metal sheets recovered from an old fridge.

5- Insulation as a rockwool or EPS, 1.6 m2

6- Metal or PVC pipes, square or circular profile.

6- Black spray paint, for can coating. Better if it is high tempertaure paint.

7- Silicone, glue or sealant paste.

Tools:

1- Drill and crows.

2- Circular saw.

3-Gloves.

4- Jack

5-Tape measure.

6- Glue gun.

7- Orbital Electric Sander

8- Electric Nail Gun

To determinate the frame size, i took the external dimensions from my glass (aluminium frame included, 1910x910mm).

Because of that, i took several plates of wood and plywood that i found and i cut it with a circular saw, as the following dimensions:

-2 plates 1860x200 mm for external long sides

-2 plates 1820x160 mm for internal long sides

-2 plates 920x200 mm for external short sides

-2 plates 880x160 mm for internar short sides

-1 plate 1820x920 mm for bottom. This plate will have two big holes centered at the ends, depending of what pipes we are going to use to circulate warm air. In my case, two holes of 150mm diameter.

-2 plates 880x150 mm for support can rows and delimite air chambers. This plates it will be drilled by the same crowns that we will use for cans, in order to determinate where each row it's going to be situated. In my case, i situated 11 holes at a 70 mm distance between them.

After to get all of the wood plates, we will join them by glue or silicone and ensure every join with some wood screws every 300-400 mm.

Is needed to remove bottom and top part from the cans. You can use drill with specific crown depending on the diameter. In my case, i used crown of 40mm for the bottom and 45mm to the top.

Be carefull, it can slide so be sure that you apply a little presure trought drill.

After be removed both sides, is needed clean it up and dry each one.

Finally, we need to make 11 groups of 12 cans. And stick them together by silicone or glue making a long row, as I show in the photos.

Between bottom part of frame and rows of cans, is needed to add a plate of insulate.

You can use rockwool or EPS plates, cutted and fitted.

Note: In order to avoid movements of the insulate, it's recomendable to put some screws fitting it.

Now it's time to assemble and join the rest of pieces leaving everything as airtight as possible.

Joining the ends of can rows to the frame, leaving two departmentes just conected troguht the cans. After, add a sheet metal on top of each side leaving it totally airtight.

You sould pay attention to ensure all joints have been well sealed.

Note: Is recomendable use a metal sheet between cans and insulate, in order to store more heat inside. After will be recovered by recirculated air. You can screw it to the bottom to avoid the movement of it.

Coat whole the internal part with black spray paint.

Why black color? Because dark color absorbs all wavelengths of light and reflects none. Consequently, black absorbs the most heat and eficiency will be improved.

Note: Highly recomendable the use of high temperature resistance black paint, because, inside could get around 80-100 ºC.

Using silicone or any glue high temperature resistant, is needed to fit glass door at the top of the wood frame and get it watertight for all the boundary.

After that, is recomedable to cover whole de wood frame with any plastic or metal sheet in orther to avoid damaged due to bad weather. In my case, i took pieces of sheet metal that i recovered from sides of an old fridge and some others.

Note: Highly recomendable the use of Policarbonate instead of glass, in order to reduce the weight and fragility.

Depending on where we would like to support the air heater, we would need to make a metal or wood suport structure.

In my case, i got some inox pipes and i built by weldering a strong struture to hold it on the wall. But you can also hold it by PVC or wood structure or just support it between the floor and wall.

The suport structure is inclinated 52º to get the highest eficiency according to the latitud of my location.

Conecting solar heater to the wall of the room trought flexible or rigid pipes, whatever you think better, but especially well thermally insulated, one pipe will be the inlet of air and trought the other it will return air to the room, going first inside the solar heater.

To get the recirculation forced of air, i got a fan from an old air extrator. Wich is located at thecollector air outlet.

1- First of all,nobody wants to be hurt, so use gloves and glasses protection in every step that we need to work with electrical or cutting tools. Safety first.

2- For getting a high eficiency, is recomendable use a high fan rate. Outlet emperature won't be as high but the system eficiency will be high. As well as, taking cold air from the lower part of room and taking it out to upper part we will help to the air cycle into the room. And of course, be sure that each joint has been well sealed.

3- In summer, temperature can be too high, so could be necesary to cover it.

4- If you want to control the fan automaticly, you just need to get a temperature controler with a sensor incorpored by Amazon or Aliexpress. Depending on voltage of your fan, you can choose the one that best fit. It's simply a solenoid which will turn on or turn off depending of the temperature you have preprogramed.

5- Even if your idea, is getting a totally ecofriendly sun heater, you can add a solar panel (25 watt) near, normaly with a little 12 volts battery and a fan which work rate is 12-24 volt, you could make it work totally independent and sustanaible. A cheapest solar kit (25 watt solar panel, inversor and small 12 volt battery) could cost aproximatly 60€.