DIY Solar Air Heaters

Prepare the materials for the opening

• Cut a section of plywood to the width of the opening or window that is going to used for the solar heater. The plywood should be longer than it is wide, and can rest on the ground if used on the first floor. Secure four 2x4s with screws or nails to the top edge of the plywood, to form a shallow box. A small piece of plywood can be cut for the top angle of the opening, as an extension to match the top edge of the box (if it is at an angle). Other types of openings can be holes or small slits in the side of the building, but there must be two and one must be higher than the other.
  
  

Create an air path

• Solar air heater path
  
  Align 2x4s into the shallow box to make a path for air flow, and secure them with screws or nails. The lower hole is the intake and the upper hole is the exhaust. As air is heated in the box, it moves toward the upper hole, drawing colder air from the bottom hole (and the home's interior). This air remains in motion while the sun is shining on the box, moving cold air, heating it, then letting it escape into the home. The air will become hotter the longer it stays in the box, but a maze that is too tight can prevent the heater from working properly. Good air flow and acceptable heating can be accomplished with three or four turns in the air path.
  
  

Painting the maze

• Paint or cover the interior of the box, where the 2x4s make a maze, with a flat black color. This will capture maximum heat from the sun and the box will be more efficient. Allow the paint to dry completely.
  
  

Clear heat trap

• Cover the top of the box with a clear sheet of plexiglass by using an adhesive or drilling small holes into it for screws. The plexiglass covering is crucial, as it seals the box and traps the heated air, but allows sunlight to penetrate.
  
  

Hook up the solar heater

• Connect the box's intake and exhaust to the openings in the home with flexible ducting or a top section of plywood, depending on which type of heater is made. The lower hole or slit should be placed as low as possible in the interior of the home with flexible ducting, and the upper hole should be as far above the lower one as is feasible.