 Image Number 3 for United States Patent #4429680.
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.
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