The present invention relates to air conditioning and heating systems and more particularly to an air flow control mechanism which can be readily inserted into an air duct of an existing air flow system without substantial structural modification of the duct system and without shutting down the air flow system.
For examples of conventional air flow control mechanisms, attention is directed to the U.S. Foster Pat. No. 3,366,141, issued Jan. 30, 1968; the U.S. Foster Pat. No. 3,495,521, isued Feb. 17, 1970; the U.S. Foster Pat. No. 3,282,504; issued Nov. 1, 1966; the U.S. Bishop Pat. No. 3,123,098, issued Mar. 3, 1964; and the U.S. Leigh Pat. No. 2,397,672, issued Apr. 2, 1946.
USPTO Backgrounds
USPTO Backgrounds