Anti-vacuum valve for commercial and domestic espresso machines.

Anti-vacuum valves prevent the buildup of a vacuum withing espresso machine boilers as they cool. As the boiler cools steam condense back to water and the steam/water volume reduces creating a vacuum, the anti-vacuum valve opens to allow the intake of air to prevent a vacuum being created. When a cold espresso machine begins to heat and steam is produced, the pressure closes the anti-vacuum valve, creating a sealed boiler. A worn anti-vacuum vale will allow steam to escape the boiler and should be replaced immediately.