1 Answers
An automatic bleeding valve or air release valve is a plumbing valve used to automatically release trapped air from a heating system.
Air, or other gas, may collect within plumbing. For water delivery systems to taps and basins, particularly with good main supply pressure, this air is usually flushed through with the water flow and does not cause a problem, although in some hot-water systems air locks can be problematic.
In a closed heating system though, it has no other means of escape and builds up. An air bubble trapped within a radiator means that no hot water circulates in the upper part and so the heating power of the radiator is reduced. If air is trapped within the boiler this may cause pump cavitation or boiling and overheating within the heat exchanger.