AAVs are typically available with 1 ½”, 2”, 3” and 4” adapter connections. The adapter size is based on the diameter of the vent pipe it is being installed on. Generally, a vent should be sized to be half the pipe diameter of the drain it is serving (refer to local codes for specific vent size recommendations).
Some publications list a rule of thumb that suggests Air/Vacuum Valves be 1 in. (25 mm) per 1 ft. (0.3 M) of pipe diameter (4).
Individual and branch-type air admittance valves shall vent only fixtures that are on the same floor level and connect to a horizontal branch drain. Individual and branch air admittance valves shall be located not less than 4 inches (102 mm) above the horizontal branch drain or fixture drain being vented.
The other potential problem with using an AAV instead of a vent pipe is that if you ever get a blockage in the system that prevents the gasses from being pushed down into the sewer, those gases will have nowhere else to go.
AAV location
It must be located a minimum of 4” above the horizontal branch drain, 6” above any insulation material and within 15 degrees of vertical. AAVs cannot be permanently covered and should be installed in an area that allows air to enter the valve.
Valve Sizing
A general practice to determine the correct valve size is to use the equation Q = Cv√(ΔP/G), where Q is the capacity in gallons per minute, Cv is the valve flow coefficient, ΔP is the pressure differential in pound per square inch, and G is the specific gravity of the fluid.
4.4 The 82mm, 100mm and 110mm valves are desigined for use on discharge stacks up to 45 metres or 10 storeys high.
Five DFUs for the bathroom group, three for the washing machine and one for the laundry tub. This example needs an AAV of at least nine DFUs. It is acceptable to oversize an AAV; however, an undersized AAV will not allow the plumbing system to breathe properly.
Air admittance valves often feature rubber seals, to help create a complete seal, increasing the effectiveness of the valve and preventing any odours from escaping through small gaps.
Available in different sizes, AAVs can be used to vent an individual fixture, a complete branch, or an entire stack of vents.
Air admittance valves have a typical life expectancy of 20-30 years, so if you start to have issues with sewer gases or smells being released around your sink or in the attic-wherever installed- the air admittance valve could be faulty or failed and should be replaced as soon as possible.
Air admittance valves are typically placed between the P-trap of a fixture and the drain line. They're usually mounted on one leg of a sanitary tee, with the other leg going to the drain. The unit must be placed per local codes and the manufacturer's instructions.
How high should you install the air admittance valve? The short answer is a minimum of 200mm above any water entry point. So if you imagine your soil pipe run, then durgo valve / AAV must be fitted above the highest connection to the soil pipe from any sink, bath or toilet that is connected to it.
Sure-Vent® Air Admittance Valves comply to ASSE Standard 1050 and 1051 and IAPMO listed sizes. Oatey Sure-Vent® AAVs are available in four sizes ranging from 8 Stack/24 Branch DFU to 160 Stack/500 Branch DFU.
Air admittance valves are not permitted in spaces where pressure conditions adversely affect the valve's operation. They are also not allowed in concealed wall and ceiling spaces used as plenums as part of an air distribution system that is under negative or positive pressure.
This is the measure of flow capability—how many gallons per minute that can flow with a pressure loss of 1 psi. You will want to select a foot valve size that maximizes flow and minimizes pressure loss. Pressure rating is also a consideration.
The valve length that you should choose depends on the depth of your bike wheel rims. If your bike wheel has a shallow rim depth of around 30mm, then you should use a valve length of 32mm. If you have a deeper rim depth, choose a longer valve length.
The Studor vent lets that air to be sucked in the pipe during water flow but doesn't let sewer gas escape out. Code is the thing that determines pipe size and also water flow. Hence no studor vents are permitted to toilets because more air is required to keep water flow going with more waste added to the toilet.
The AAV is a one-way air valve which opens to allow air to flow into the system and balance the pressure. Once balanced, the valve will then close and create an airtight seal stopping any odours entering the building. By only opening one-way, the open valve draws in clean air, but stops any foul air escaping.
Sometimes you may find that even with an air admittance valve, there are still clogs and a sewer odor. While this is rare, it is possible. Remember that these valves should last anywhere from 20 to 30 years, so if they are only lasting for a couple of years, there may be some problems that need addressing.