Abstract: A solar collector apparatus and method for a collector adapted to be mounted on a structure and connected to supply and discharge of fluid to be heated by the collector is disclosed, comprising a layer of insulation laid upon the structure; fluid carrying means for the heat transfer fluid, mounted atop the insulation and exposed to solar radiation; at least one layer of transparent material positioned above an air space over the fluid carrying means for insulating the fluid carrying means from ambient temperatures; a plurality of outer frame members having a cross-section defining an interconnection opening, a stepped portion to support the transparent material and means for attachment to the structure; and, at least one interconnection member dimensioned to fit tightly but slideably within the interconnection opening of the outer frame members and extend therefrom, whereby two or more outer frame members may be aligned by placing them over the interconnection member.

Abstract: A solid-fuel-burning heating unit comprises a heat transfer fluid circulating through a first heat exchanger in a hollow metal jacket of the heating unit, and through a second heat exchanger in the path of the exhaust gases. The heat exchanger unit in the exhaust path is adapted for ease of cleaning and is further adapted to be reversed in position. The system may be used in a new installation or as a retrofit.