What is an Air Admittance Valve?

What is an Air Admittance Valve?

Also known as AAV’s or Durgo Valves, air admittance valves make sure that the pressure within your soil pipes remains normal. Negative pressure builds up within your soil pipes when waste water flows through. For example, when your toilet is flushed negative pressure increases due to air being carried along the pipe with the water.

When are Air Admittance Valves used?

To restore the balance of pressure within the pipes, air is usually drawn into the pipes from plugholes. This can unfortunately cause bad odors, waste water rising into the sink from the trap, poor water drainage and loud gargling sounds.

Traditionally, an open pipe outlet is installed on the roof to allow air to be drawn in from the outdoors. This prevents air being drawn in from the plugholes. Therefore, preventing the unfortunate issues previously listed. Although, when an open pipe outlet is not possible, an air admittance valve is the perfect solution.

How do Air Admittance Valves work?

AAV’s are designed to recognize negative pressure. Once they detect negative pressure, the valve opens to allow air into the pipe. This air allowed in balances the pressure and the valve then shuts itself again. AAV’s often come with rubber seals to create a complete seal, increasing efficiency and preventing odors.

How are Air Admittance Valves fitted?

Usually AAV’s are fitted using a simple push-fit joint. Push-fit joints are super easy to fit together and require no tools. They also feature a rubber seal to provide an air and watertight fit. Although, they can also be purchased with solvent welt joints. Solvent welt joints require an application of solvent to bond via a chemical reaction.

Where should Air Admittance Valves be fitted?

AAV’s must be fitted onto a soil pipe at least 200mm above the highest water entry point on the system. Due to aesthetic purposes, they are usually installed in the loft or cupboard. Most AAV’s must be fitted indoors. Although if you purchase an external air admittance valve, which is both insect and frost resistant, this can be installed outdoors.

Ordering an Air Admittance Valve.

At Plumbco-online, we supply a variety of Polypipe Fittings. We highly recommend our popular Polypipe Soil 4” Air Admittance Valve – Grey. The Polypipe Soil 4” Air Admittance Valve includes solvent weld joints for quick, easy and reliable installation. It can also be used externally, not just indoors.