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Solar air heater
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Solar Air Heaters
- 1 Overview -
- 2 Two basic forms of solar air heaters
- 3 material list
- 4 tools required
- 5 skills and knowledge required
- 6 technical specs (schematic)
- 7 Estimated costs
- 8 Alternative designs
- 9 Videos
What is the device? - what does it do? - "heat exchanger"
breakdown of energy consumption - space heating large portion - benefits of solar air heater
How to calculate energy gain and efficiency.
Two basic forms of solar air heaters
Beer can and snake methods. both are easy and effective.
The simplest and made of widely available products is the pop can...
Solar ”Can” Air Heater
This simple small passive solar heater, made from recycled aluminum drink cans, can be used to heat an insulated garage or small room. 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.
The box is built from 2″ x 4″ studs and a sheet of plywood, measured to tightly hold 5 rows of 10 black-painted aluminum drink cans. The inside of the box is sealed using caulk to prevent hot air from escaping. Cold air is drawn in from a hole at the bottom of the box and heated air emerges from the top passing through a pipe into the space to be heated. A Plexiglas sheet is glued to the top of the box to let sunlight in but not let the hot air escape.
This 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.
For the air to pass through a column of cans, holes must be drilled into them. 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 inch hole is drilled in the side.
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,fireplace or stove paint is excellent for this as it will not flake off. 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.
Ideally the whole unit will be sealed with a sheet of tempered glass. However, tempered glass (unless you can find and recycle a sheet) is also very expensive. Therefore Plexiglas (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.
Required Improvements to this Design
“Snake” the cans together so the air travels farther and has more opportunity to take the heat from the aluminum cans.
Add a fan to both the intake and output sides of the unit, to move more air.
Insulate the box - bottom, sides and ends. One inch rigid foam is easy to work with.
Keep the input and output pipes short and super insulated.
skills and knowledge required
Solar data (maps)
angle and tilt of unit
technical specs (schematic)