Flush valve assemblies are described herein which include a valve body; a flush valve cover detachably connected to a flush line; a pivot mechanism capable of opening and closing the flush valve cover upon actuation; wherein the flush line is connected at a first end to a flush actuating device and at a second end to the flush valve cover, the line being capable of raising and lowering the cover upon actuation; and a float situated above the cover and connected to the flush line at a point between the first and the second ends of the flush line or by a separate float line connected to the cover. The float is sufficiently buoyant and capable of resisting the force of flowing water and keeping the flush valve cover open to allow flush water to pass through the valve body before closing the cover when the valve body is installed on a toilet.