Abstract: A valve assembly is disclosed having utility in building air distribution systems, particularly those of the variable air volume type. The assembly includes a plenum chamber having a generally cylindrical sleeve disposed therein, connected to a supply of conditioned air at one end thereof, the other end being blocked by a closure member. A generally cylindrical, balanced valve member cooperates with radially extending apertures in the sleeve to control flow into the plenum chamber. The valve member is mounted for axial movement on tubular means having a bore which extend axially into the sleeve from the closure member.In order to apply an actuating force to the valve member, connecting means extend therefrom to a position upstream from the end of the tubular means and terminate in a force receiving portion. Means are provided to apply an axial force to said portion by way of the bore in the tubular means and may comprise:1.