What is an Air Admittance Valve (AAV)? :
• An Air Admittance Valve is a device used to manage air flows in drop pipes. It helps to ventilate the network and prevents stale air reflux.
• An AAV prevents dumping problems in gravitational drainage systems by allowing air to enter when there is a depression in the water pipe. It can be used instead of external roof vents. In short, it suppresses gurgles and smells, prevents trap draining and improves flow.
It can be placed under the overflow level of a device and is capable of operating at temperatures between -20°C and +60°C.
How it works
The valve uses an innovative opening/closing technology to allow air to pass through. This concept is based on controlled deformation of the membrane.
With this new design, there is no need for constant up and down movements around an axis (central or otherwise), thereby eliminating the risk of friction. The controlled deformation technology therefore limits fouling up and premature ageing of the product.
With its unique design, Nicoll’s AAV can be installed in attics instead of a roof crossing solution (in accordance with Art 42). This has the following advantages:
Reduced installation time:
• No roof work required.
• Limited potential conflict between different professions.
No roof sealing problems:
• No risk of water infiltration through the roof where the roof crossing solution is installed.
No heat loss:
• With energy standards becoming ever stricter (low energy consumption houses, etc.), this solution eliminates the risk of heat loss through the roof.
High resistance to extreme temperatures:
• This solution can be installed in attics with no additional frost protection required (e.g. expanded polystyrene insulation).
The silicon membrane is naturally resistant to frost.
Silicone membrane Airtightness system
This membrane is the main component of this new, patented design.
• The inner face is subject to variable pressure from the air inside the drop pipe, while the outer face is subject to stable atmospheric pressure.
• The weight and sloping position of the membrane (40°) ensure that the AAV remains fully airtight.
• When a depression occurs inside the drop pipe, the membrane deform itself, allowing air to pass through until the internal and external pressure are equalized. When the internal pressure rises, the membrane forms an airtight seal inside the drop pipe to prevent reflux of stale air.
Silicone membrane characteristics
This airtight sealing system is allowed by a silicone membrane (exclusive to Nicoll), with unique properties. The membrane has four technical characteristics which, together, create a fully airtight seal (even at extreme temperatures):
• Flexible : the membrane moulds to the shape of its «seat», thereby preventing any potential leaks.
• Hard-wearing : the membrane is sufficiently rigid to be able to withstand high pressures.
• Anti-bacterial: the membrane prevents the formation of bacterial biofilms, which often cause fouling up in valves and can lead to a loss of airtightness.
• Resistant to frost: the Nicoll air admittance valve can be installed in attics with no additional protection required (e.g. expanded polystyrene insulation). The membrane remains fully operational, even at -20°C.
THE Nicoll advantage
Attractive, clever design
• With its slim-line design, this new range can be installed in a corner.
• With its white colour, it can be installed next to other sanitary appliances.
• Its attractive design means that, for the first time, a valve can be installed in a visible location.
