Automatic air vent

Positioned at high points in the system where air will collect.

Automatic Air Vents release air as it collects at that point. Usually fitted with screw-down cap, which under normal operation must be left loose.


Some valves are fitted with a secondary, manual vent. This is operated by removing the (red) cap and depressing the valve found thereunder. This can also be used to allow air into the system when draining down, again by depressing the valve. The cap on this side should be screwed down when not in use.