A ventilating device for ventilating a housing, includes first and second blowers, a flow chamber with an inlet opening, an outlet opening, and an equalization opening connecting the flow chamber between the inlet opening and the outlet opening with the environment, a freely movable cover element for partially covering the equalization opening in such a manner that passage of the flow is blocked in one direction but cleared in the other direction, and an ascending pipe. The elements in the ventilating device are arranged in the sequence first blower, inlet opening, flow chamber, outlet opening, second blower, and ascending pipe. The equalization opening is at least partially open at all times, so that the equalization opening displays a greater flow resistance than the inlet opening of the flow chamber.