Abstract: An air vent (1) for heating systems is provided that includes a float valve inside a vent housing (6). The float valve is placed upstream of an air-outlet opening. The air vent includes a float (4) which is displaceably guided inside the vent housing (6) and which interacts with the float valve, and has a cap or bell-shaped design. Air is evacuated from the interior of the cap or bell-shaped float (4) via at least one vent opening (7). The vent housing (6) has an inlet opening (12) that leads into the float interior. The air vent is characterized by its comparatively compact design and trouble-free functioning of the float valve located inside the vent housing (6).