What Is a Boiler Vent Valve? The boiler vent valve (also called an anti-vacuum valve or anti-siphon valve) is a small but critical safety and functional component on your Conti commercial espresso machine. With a 1/4" male (BSP) connection, it allows air to enter the boiler during cool-down, preventing a vacuum from forming that could collapse the boiler or cause water to siphon back into the mains supply. It also vents steam during initial heat-up. Compatible Conti Machines This valve is designed for Conti commercial espresso machines using a 1/4" BSP vent valve connection. Contact us with your machine model or serial number to confirm fitment before ordering. Specifications Type: Vent valve / anti-vacuum valve / anti-siphon valve Connection: 1/4" male (BSP) Brand: Conti Weight: 200g Symptoms of a Faulty Vent Valve Continuous dripping or steam venting from the valve during normal operation Machine taking longer than usual to reach operating temperature Gurgling sounds from the boiler during heat-up or cool-down Water siphoning back through the inlet line when the machine is switched off Valve stuck open or closed — visible mineral scale or corrosion on the valve body How to Replace a Boiler Vent Valve Isolate the machine from power and water supply; allow it to cool and fully depressurise Locate the vent valve on the boiler — typically on the top or side of the boiler body Unscrew the old valve using the 1/4" BSP thread; apply thread tape to the new valve Thread in the replacement valve and tighten firmly — do not overtighten Restore power and water; heat the machine and check for leaks and correct venting behaviour Tip: Vent valves are prone to scale buildup in hard water areas. Descaling regularly can extend valve life significantly. Why Buy From Bear Coffee Machine? Genuine Conti-compatible vent and anti-vacuum valves Fast shipping from Sydney, Australia Expert support — we can confirm the correct valve for your machine