Make a Simple Solar Air Heater
Make A Simple Solar Air Heater
Heat a room or outhouse with a solar heater made from recycled aluminium cans
solar | heatingUsing the sun to
heat water is a very cost effective way to save energy. Typically
payback on even the most expensive systems is under ten years, with
DIY Solar Water Heaters paying for themselves in just a few months. Similar techniques can be used to make a
Solar Space Heater - a device which warms the air inside a room or building.
Solar Garage Heater
Pictured above is a simple small
passive solar heater made from recycled aluminium drinks cans and used to heat a garage. If the building to be heated is well insultated, a solar heater such as this can lift the
temperature by a significant number of degrees. A larger heater or a number of similar heaters can be used to heat larger spaces, or to heat smaller spaces to a higher temperature.
Offcuts of 2 x 4 and a sheet of plywood were used to build a box to tightly hold 5 rows of 10 black-painted
aluminium drinks cans. The inside of the box was then sealed using
caulk to prevent hot air from escaping. Cold air is drawn in from a hole at the bottom of the box, and the heated air emerges from the top passing through a pipe into the garage to be heated. A plexi-glass sheet was glued to the box to let sunlight in but not let the hot air escape.
Click here to find out more about this basic
almost free garage heat project. Read on to find out how to make your own
solar heater.
Building a Solar Space Heater
This type of
solar space heater works by drawing the air to be heated into the bottom can of a column of cans. The air is then heated inside the cans by the sun's energy and the hot air within them rises upwards (thanks to
convection) to be fed into a pipe which re-enters the building to be heated.
Building the Box
First of all make a box out of whatever scrap materials you have to hand. Set the dimensions to that the width of the interior of the box is exactly the same as the width of however many columns of cans you would like to use in your heater.
The height of the box should be the same as however many cans you would like to have in each column plus a few centimeters.
For increased efficiency, you may choose to insulate the box to prevent heat escaping (by
conduction) through the plywood. If so, size your box so that the cans and insulation will fit snuggly.
Drilling the Cans
For the air to pass through a column of cans, holes must be drilled into them. Remember that there is already a hole at the top of each can out of which the drink is poured. That just leaves holes at the bottom of each can to be drilled.
In the bottom can of each column a 1/2 to 1 inch hole is drilled in the side. (see image below)
The rest of the cans in the column have a similiarly sized hole drilled into the bottom. See image below)
Building the Can Columns and Painting
Then the cans of each column are glued together using caulk or silicon adhesive and painted using
black paint to help them absorb the sun's energy. Barbecue or fireplace/stove paint is excellent for this as it will not flake off, but any marine grade paint will do a similar job - just make sure it has a totally
matt finish.
The inside of the box must also be painted with the same paint before the columns of cans are glued into position using
caulk or
silicon adhesive. The outside of the box should be treated with preservative, varnish, or paint to help it survive the elements for many years.
Sealing the Solar Heating Box
Ideally the whole unit will be sealed with a sheet of
tempered glass - of the type used in car windscreens. This glass is very strong and resilient to heat. However, tempered glass (unless you can find and recycle a sheet) is also very expensive. Therefore plexi-glass (plastic) can be used, but it will degrade far more quickly and become opaque blocking out the sunlight.
A hole at the top of the box acts as the
hot air outlet and can be connected to the building/room to be heated using an insulated pipe.
Possible Improvements to the Design
Pictured above is an alternative design in which the cans are all joined together in a
snake. The illustrations shows an array of just 3 x 3 cans for simplicity however hundreds of cans could be joined in this way to make a larger heater.
Air inside this
snake would rise much more slowly through the heater (than was the case in the previous design) since
it has a much longer path to travel, and it is obstructed from rising straight upwards. Therefore the air can be heated to a much greater temperature.
A
PV Electric Solar Panel could be used to power a small
fan (such as that used to cool the processor in a computer) to drive air through the
snake. The final temperature achieved would be lower, but having a large quantity of 30 degree Celcius air entering a room is much better than a much smaller quantity of 50 degree Celcius air.
Solar Heating Links
Instructions on building a similar
Beer Can Solar Heater are available on the
Squidoo website. An alternative very simple but larger design is detailed on this
instructables page:
Solar Heater - no cans required.
Article Last Modified: 14:55, 1st May 2007
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