Abstract: An expansion tank includes a tank body mounted inside a housing forming a sump, and defining an internal expansion volume. A fluid inlet opening in the tank body is in communication with the sump and the expansion volume. A combination valve may be disposed on a lower end of the tank to control fluid flow between the sump and the expansion volume. The valve may be a combination duckbill valve and umbrella valve. Fluid enters the expansion volume through the umbrella valve when sump pressure exceeds expansion volume pressure by a first predetermined amount, and fluid exits the expansion volume through the duckbill valve to the sump when expansion volume pressure exceeds sump pressure by a second predetermined amount. The tank body may include a cover on which an inlet tube is formed.

Abstract: An expansion tank includes a tank body mounted inside a housing forming a sump, where the tank body defines an internal expansion volume. A fluid inlet tube on the tank body has an upper end open to the sump and a lower end open to the internal expansion volume. A single 2-way check valve is located at the lower end of the tube, and fluid enters the expansion volume when the pressure in the sump exceeds the pressure in the expansion volume by a first predetermined amount, and fluid exits the expansion volume to the sump when the pressure in the expansion volume exceeds the pressure in the sump by a second predetermined amount. The check valve may be a combination duckbill valve and umbrella valve. The tank body may include a cover on which the inlet tube is formed.