Abstract: A hot air generator is constituted by cast iron plates assembled together and sheets of steel cut out and bent in order to rest on elongated plane elements with which the plates are provided, perpendicularly to their surface, in such a manner as to form a closed shallow conduit.A first horizontal portion of the conduit, provided with a drawer which serves as an ash pan and as an adjustable member for leading in external air, forms the hearth and a chamber for preheating of the air. Two vertical portions serve as chambers for slowing down and for heating the air. The second vertical portion is constituted by the rear face of a throat of moulded cast iron which permits the conventional operation of the fireplace.

Abstract: A prefabricated metal throat, for a chimney, is assembled by simple interengagement of two identical elements of a first type with two identical elements of a second type to provide a principal body shaped as a truncated regular pyramid with a rectangular base. The elements of the first type have C-sections in planes parallel to the bases, and each forms a terminal face and two return angles of the throat. The elements of the second type join the return angles together for forming front and rear faces of the throat. The elements are cast in iron, and the second type are trapeziums in which the oblique sides are inclined to the base at an angle according to the size of the chimney, so that the horizontal parts of the C-sections do not exceed a length limit compatible with core-less moulding of the cast iron.