Understanding Studor Air Admittance Valves (AAVs) –
your questions answered
Air Admittance Valve (AAV) technology has been around since 1975 and educating the end users about guidelines and how AAVs can solve bad smells in a drainage system is a continual process, which is of a high priority to Studor.
Here are common questions answered, with links to other helpful areas of this website and handy hints along the way. Please contact our distributor or subsidiary in your country for any further assistance.
Q1. Why is it important to allow air circulation in a building’s plumbing or drainage system?
Q2. What is “new” about the Studor AAV?
Q3. How new is this technology, is it effective, and who is it used by?
Q4. Do Studor AAVs fit all applications?
Q5. Are Studor AAVs durable?
Q6. Can Studor AAVs be used in extreme temperature conditions?
Q7. Where can the Studor AAVs be installed?
Q8. Is an open vent pipe still required?
Q9. Do the Studor AAVs need to be maintained or replaced after a certain time?
Q10. What is a positive pressure?
Air circulation in the drainage system allows trap seals to work properly. Without ventilation, negative pressure (vacuum) following any discharge would result in the siphonage of the water seal from the trap. The very well known “gurgling” noise is the most common evidence of siphonage. The trap seals form a water barrier that prevents sewer gases and foul odours from entering the living spaces of the building – gravity and air pressure differential create a simple solution that has been working well for decades!
In the past, open vent piping was the only answer to maintaining pressure control and trap seals – the pipes extended through the roof of the building to admit air.
Now Studor technology has changed considerably and you can have a better solution that saves you money on installation. More importantly, you will have a more effective drainage system. Basically, by using Studor AAV solutions, you will allow air to enter WHERE and WHEN required: practically an instantaneous pressure balance at the Point Of Need utilising the concept of Active Control.
The Studor range offers an alternative to installing an expensive piping system for plumbing ventilation by making it possible to utilise air within the building. Here are a few of the benefits of using an AAV .
Studor AAVs have been installed in millions of installations worldwide since the 1970s. The valves are tested to “AI” within European Standard EN12380:2002 – the highest rating for AAVs. Studor AAVs are used from low rise residential to high rise commercial installations; whether you are an architect, a plumber or a specifier, the range of products is universally beneficial.
Have a look at our Guide to AAVs .
The Studor Mini-Vent is designed to ventilate from single fixtures to all fixtures connected on the same branch, while the Studor Maxi-Vent provides ventilation for stacks.
The Studor range of products can also be fitted into existing installations (retrofit option or as a problem solver) or in new builds. Have a look at our range of case studies to find out more.
Yes! Studor AAVs comply with all major international standards, including the European ones and the American ones under ASSE 1050 and 1051; these are the performance requirements for stack AAVs for sanitary drainage systems. Studor products are durable because they have been tested to 500,000 cycles (250,000 at -20°C and 250,000 at +65°C at 6 monthly intervals by a third party testing body). A more extensive test was also conducted over ten years ago where the valves were subjected to the equivalent of 1.5 million cycles; this equates to 80 years of service without failure. In addition, each valve is individually tested to fully prove its sealing function to any pressure, as opposed to "batch testing", before it is packaged and shipped.
Studor products are also durable because of the type of plastic they use. An ABS plastic is a stable material under different temperatures, which means that it will not fatigue. Plus, as there is no moving part or mechanical device within the Studor AAVs, it means that there is no compromise on efficiency. This is why Studor products offer a lifetime warranty.
Studor AAVs are designed to comply with temperatures ranging from -20°C to +60°C. The Maxi-Vent has been tested beyond this and is guaranteed from -40°C, subject to following the installation guidelines. Additional protection for extreme temperature is provided via the packaging where necessary and a dedicated aluminium cover is available to further protect the Maxi-Vent from UV, inclement weather and animals/birds in cases of external installation. In addition to this, we also have specialist products which can be used in more diverse, technical applications, for example laboratories.
The Studor Mini-Vent can be installed above the fixture and up to 1000mm below the “flood level” of the fixture. It can be installed under the sink, in roof space between floors, in wall spaces, etc. – as long as the valve is installed 100mm above the horizontal waste to the fixture that it serves. There must be free movement of air to the valve. The Studor Maxi-Vent can be installed at the top of the stack in the loft, eliminating the need to penetrate the roof. The Studor Maxi-Vent must be installed 150mm above the highest branch connection.
It depends on the type of building and the local building regulations. The purpose of the open vent pipe is generally to relieve any positive pressure in a in medium rise building drainage system, or generated from the main city sewer system. As for low rise, there isn’t any positive pressure generated from the building drainage system, and for high rise buildings the positive pressure is addressed by the P.A.P.A. (Positive Air Pressure Attenuator).
In the presence of many stacks (either from one building or from a series of individual low rise villas), one open vent is recommended to relieve the constant positive pressure build-up that can occur if the main sewer is blocked for some time. In higher buildings it is recommended that the stack closest to the main sewer is the one having an open vent. In all applications, refer to your local building regulations for confirmation.
The Studor AAVs are maintenance-free.
As long as they have been installed in accordance with our installation instructions, are protected from building dust, and have free movement of air, no maintenance is required.
Positive pressure is generated in two forms within the drainage system: a) constant pressure – which is the slow build-up of pressure due to a long-term blockage within the system; and b) positive transients – which are produced at every discharge of the system, mainly at the base of the stack (as they are generated every time a partial blockage of the air flow is generated). The positive transient is the most harmful to the trap seal, as it travels through the system at the speed of sound, 320m/s, with an average volume of 2 litres of air for standard stack size (DN100).
Please refer to our products page which gives you further information about our range of products. Here you will see how we regulate pressure in the different drainage installations.
For further details please refer to the links on this page or contact the distributor in your country who will assist you with your questions or advise you how to place an order.