Installing An Air Admittance Valve (Video)
Air admittance valves (AAVs), also known as Durgo valves, revolutionise the traditional approach to venting soil stacks by eliminating the need for the pipe to terminate above the roofline. They offer a modern, efficient, and cost-effective solution for balancing pressure in soil pipe systems.
Traditionally, soil stacks had to be vented to the atmosphere, requiring the pipe to:
- Terminate above the roofline, at least 900mm above the highest window and 3 meters away laterally from any window.
- Involve significant work, including scaffolding or roof penetration for internal stacks, followed by re-weathering the roof to ensure it was watertight.
This process was labor-intensive, costly, and required work at heights.
How Air Admittance Valves Work
Air admittance valves simplify venting by replacing the need for an open pipe. They:
- Allow air to enter the soil stack when there is negative pressure (e.g., during flushing), balancing the system.
- Prevent foul odours from escaping, as the valve is one-way and remains closed when not in use.
Advantages of Air Admittance Valves
- Eliminates Roof Work: No need to extend the soil pipe above the roofline, avoiding scaffolding and re-weathering.
- Compact Installation: Can be fitted just 200mm above the highest water point (wet entry point) on the soil pipe.
- Improved Aesthetics: Removes the need for visible pipes above the roofline, which can detract from the building’s appearance.
Types of Air Admittance Valves
First-Generation (Internal): Installed indoors, typically in loft spaces or hidden in walls or cupboards. Requires placement above the highest water point on the soil pipe.
Second-Generation (External): Can be installed outside the building, offering greater flexibility while performing the same function.
Installation Tips
- Always fit the valve 200mm above the highest water point to ensure proper functionality.
- Ensure the valve is accessible for maintenance.
- For external valves, verify it is designed for outdoor use and properly protected from the elements.
By using an air admittance valve, you can avoid the hassle of venting soil stacks above the roofline, saving time, money, and effort while maintaining an effective drainage system. Whether for a new installation or a retrofit, AAVs are a game-changer for modern plumbing.
The video below gives a brief explanation of how air admittance valves work, and where exactly on the soil stack they should be installed.
