Cooling system with water guided in the circuit as the heat transport medium, comprising an application device flowed through by the water and functioning to apply heat to the water, a heat exchanger flowed through by the water and functioning to discharge heat to the surrounding air, and a water container, which is arranged in the flow direction between the heat exchanger and the application device in a tube arrangement, which connects the heat exchanger , the application device, and the water container with one another and has at least one circulating pump, characterized by the following features: - the heat exchanger comprises an inlet connected to an inlet manifold and an outlet connected to an outlet manifold on its one, first end region and a deflection manifold on its other, opposite second end region ; - the inlet manifold and the outlet manifold are arranged in a V shape with respect to each other; - the deflection manifold comprises a first branch and a second branch , which are arranged in a V shape with respect to each other, and a connecting branch connecting the first branch and the second branch to each other at their respective upper ends; - a first tube arrangement which can be flowed through, extends between the inlet manifold and the first branch of the deflection manifold , and rises in the flow direction from the first end region in the direction of the second end region of the heat exchanger , and a second tube arrangement which can be flowed through, extends between the second branch of the deflection manifold and the outlet manifold , and descends in the flow direction from the second end region in the direction of the first end region of the heat exchanger , wherein the connecting branch of the deflection manifold can be flowed through by the entire amount of water flowing through the first tube arrangement ; - the water container is unpressurized; - an open ventilation line, which can be flowed through from the deflection manifold to the water container in a cooling operation, extends between the water container and the connecting branch of the deflection manifold . - the heat exchanger comprises an inlet connected to an inlet manifold and an outlet connected to an outlet manifold on its one, first end region and a deflection manifold on its other, opposite second end region ; - the inlet manifold and the outlet manifold are arranged in a V shape with respect to each other; - the deflection manifold comprises a first branch and a second branch , which are arranged in a V shape with respect to each other, and a connecting branch connecting the first branch and the second branch to each other at their respective upper ends; - a first tube arrangement which can be flowed through, extends between the inlet manifold and the first branch of the deflection manifold , and rises in the flow direction from the first end region in the direction of the second end region of the heat exchanger , and a second tube arrangement which can be flowed through, extends between the second branch of the deflection manifold and the outlet manifold , and descends in the flow direction from the second end region in the direction of the first end region of the heat exchanger , wherein the connecting branch of the deflection manifold can be flowed through by the entire amount of water flowing through the first tube arrangement ; - the water container is unpressurized; - an open ventilation line, which can be flowed through from the deflection manifold to the water container in a cooling operation, extends between the water container and the connecting branch of the deflection manifold . <EOS>