A fryer system and a check valve useful in the fryer system or in other applications. The check valve does not require electricity or springs, but rather operates based on fluid flow and/or pressure. The check valve includes a sealing member that is disposed in a chamber. The chamber is in fluid communication with ambient air and a fluid container, such as a rear return manifold in the fryer system. As fluid, such as cooking oil, is supplied to the manifold, the cooking oil rises in the chamber of the floating check valve. The sealing member floats on the rising cooking oil until it seats in a seal so as to close the fluid communication with ambient. When the cooking oil is drained from the manifold, the sealing member disengages from the seal and floats in the chamber to a retainer that allows ambient air to pass through the fluid communications and chamber to counteract any vacuum in the ullage of the manifold.