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A thermally actuated damper for insertion in the flue pipe of furnaces consists of a cylindrical section of pipe having a diametrically extending bar fixed across its interior. The bar supports a pair of identical, semi-circular vanes formed of a bi-metallic laminate which project in a common direct

A thermally actuated damper for insertion in the flue pipe of furnaces consists of a cylindrical section of pipe having a diametrically extending bar fixed across its interior. The bar supports a pair of identical, semi-circular vanes formed of a bi-metallic laminate which project in a common direction from the bar. When the furnace is operating the hot flue gases cause the vanes to bend into abutment with one another so that they extend longitudinally along the flue pipe and allow substantially unrestricted flow of vent gases. When the furnace is off the cooling blades bend outwardly, toward the walls of the flue pipe, substantially blocking the flow of gases through the flue so that the warm air from the heated space is not drawn up the flue.

대표청구항 ▼

A damper for a furnace exhaust gas flue, comprising: a cylindrical sheet metal housing section adapted to be disposed within the flue so that vented combustion gases from the furnace pass through the housing; a pair of flat members each having an elongated portion and an ear portion disposed within

A damper for a furnace exhaust gas flue, comprising: a cylindrical sheet metal housing section adapted to be disposed within the flue so that vented combustion gases from the furnace pass through the housing; a pair of flat members each having an elongated portion and an ear portion disposed within the housing with the ear portions secured to diametrically opposed points on the interior of the housing so that the longitudinal axis of the flat members extend at right angles to the longitudinal axis of the housing, with the sides of the flat members being parallel to the longitudinal axis of the housing; and a pair of semi-circular vanes formed of two separate sheets each consisting of two laminated metal layers, one layer having a relatively high coefficient of thermal expansion and the other having a relatively low coefficient of thermal expansion, each vane having a generally flat upper end with flat opposing sides and curved lower edges, means to secure the upper ends of the two vanes to the elongated portion of the flat members, the elongated portions of the two members serving to sandwich the upper ends of the two vanes together in directly abutting relationship, so that the flat side edges of the vanes extend normally to the longitudinal axis of the housing, the two vanes projecting from the flat members in the direction of the furnace free from any structure between the vanes, and being designed so that they curved outwardly, in opposed directions, when disposed at a temperature below the temperature they experience when the furnace is operating to block a major portion of the cross-sectional area of the flue, and bend under the force of their differential expansion when the furnace is operating so that their planes lie substantially parallel to the longitudinal axis of the flue, with the vanes abutting each other substantially throughout their entire lengths thereby allowing substantially unrestricted gas flow through the flue.