A Durgo valve, also known as an Air Admittance Valve (AAV), is a device used in soil and waste pipe systems to rebalance pressure and prevent issues caused by negative pressure within the pipe.
Why are Durgo Valves Needed?
When a toilet is flushed, water and air are carried through the waste pipe, creating negative pressure. This negative pressure pulls air into the system to restore balance. Without a properly functioning vent system, air may be drawn from plugholes or traps, which can lead to:
Gargling noises in sinks or baths.
Unpleasant odours released into the home due to dry traps.
Wastewater bubbling up into sinks or toilets.
How Does a Durgo Valve Fix These Issues?
Traditionally, an open vent pipe installed on the roof allows external air to equalize pressure in the waste system. However, this solution is not always practical due to:
A Durgo valve is a more flexible alternative that can be installed within the waste system itself, typically in:
Loft spaces for indoor use.
Outdoor locations, in rare cases, with proper frost and insect protection.
How Does a Durgo Valve Work?
Activation: When wastewater flows, it creates negative pressure in the pipe.
Air Intake: The Durgo valve opens, allowing air to flow in and balance the pressure.
Closure: Once pressure is equalized, the valve shuts, preventing odours from escaping.
What Causes a Durgo Valve to Smell?
If odours escape from a Durgo valve, it may indicate a failure or installation issue, such as:
Valve stuck open: May need lubrication or replacement.
Improper placement: If the valve is installed too low (below the highest water exit point).
Insufficient valves: A single valve may not be enough for larger systems.
Blocked wastewater pipe: A blockage can disrupt the system's pressure regulation.
Tips for Durgo Valve Installation
Positioning: Place it at least 200mm above the highest water exit point (e.g., from sinks, baths, or toilets).
Accessibility: Ensure the valve is easy to access for inspection and maintenance.
Compliance: Follow local building codes and manufacturer's instructions for proper installation.
A properly maintained Durgo valve ensures a balanced and odour-free drainage system.
