A spiral configured heat exchanger model, was an experiment to assess feasibility of producing a home sized unit which could possibly be produced with negligible investment.

Below a physical prototype has been worked out for efficient metal bending. The chief feature in this process is the possibity of assembly with cement. Pictured below is a workable prototype made by rolling aluminum as in the diagram above and then sealing with (in this case) portland cement . This process may also apply to thermoplastic construction. Cooperation in developing this as a marketable product is offerred.