What are the restrictions on air admittance valves?

Author: Bo Hudson DDS  |  Last update: Friday, June 6, 2025

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.

Where are air admittance valves not allowed?

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.

What are the rules for installing an AAV?

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.

What are the rules for AAV?

AAVs shall be accessible, should replacement be required. Such valves shall be installed in a location that allows air to enter the valve. The AAV shall be installed not less than 6 inches (152 mm) above insulation materials that may block air inlets or otherwise impair the operation of the device.

What is the building code for air admittance valves?

Individual and branch-type air admittance valves shall be located a minimum of 4 inches (102 mm) above the horizontal branch drain or fixture drain being vented. Stack-type air admittance valves shall be located not less than 6 inches (152 mm) above the flood level rim of the highest fixture being vented.

Air admittance valves for plumbing venting explained, [just over 4 minutes]

What are the rules for air admittance valves?

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.

What is the downside of the air admittance valve?

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.

What are the limits of AAV?

AAV vector genomes are been limited to 4.7 kb in length in order to balance the need for larger genetic constructs and effective payload delivery. Larger constructs can be attempted to be packaged in AAV vectors, however they are unlikely to be transfected and packaged enough to deliver the intended result.

When can I use an air admittance valve?

AAVs are a great alternative if you can't connect to an existing venting system due to complex pipe routing issues or obstructions – an ideal venting solution for island sinks, remote bathroom groups, home remodels and additions that would otherwise have to be tied into a stack vent utilizing specialized venting ...

How many fixtures can an AAV vent?

AAVs can vent more than one fixture, but their capacity must be matched to the total DFUs on the branch line they vent. AAVs range in capacity from 6 to 500 DFUs. To vent a clothes washer with an AAV, I run a 1 1/2-inch pipe up from a tee located about 4 inches behind the 2-inch trap, terminating it in the washer box.

Where can you put an air admittance valve?

They are most commonly installed at the end of a soil pipe, but can also be installed inline, using a branch. Typically, air admittance valves are placed within lofts or cupboards to prevent them from becoming an eyesore. However, they do require a level of ventilation.

Are studor vents legal?

Some state and local building departments prohibit Studer vents. check with the local AHJ (Authority Having Jurisdiction) for more information. Studer vents are certified to reliably. However, anything mechanical can and will fail.

How far should AAV be above trap?

The AAV's vent-tee connection needs to be above the trap weir (high-water level) in order to work correctly. Usually, within 5 feet of the trap.

Can you use an AAV to vent a toilet?

Air admittance valves are a practical option for venting toilets, but it's crucial to follow local rules.

What is the life expectancy of an air admittance valve?

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.

What height should AAV be installed?

The stack-type AAV shall be located not less than 6 inches (152 mm) above the flood level rim of the highest fixture being vented. The AAV shall be located within the maximum developed length permitted for the vent.

Are air admittance valves to code?

Individual and branch-type air admittance valves shall conform to ASSE 1051. Stack-type air admittance valves shall conform to ASSE 1050. The valves shall be installed in accordance with the requirements of this section and the manufacturer's instructions.

What is the difference between an air admittance valve and a cheater vent?

Automatic air vents are spring type devices often referred to as in-line or cheater vents, while air admittance valves have no spring. Air admittance valves are more expensive and are approved in many jurisdictions where in-line and cheater vents are not because of their moving parts (springs).

Can you use an AAV to vent a washing machine?

The AAV is used if the roofline vent stack cannot connect easily to the washer drain. An AAV is a one-way vent that connects using an adaptor on the drainpipe.

What are the disadvantages of AAV?

Limitations include the occurrence of immune-mediated toxicities, the potential loss of correction in the long run, and the development of neutralizing antibodies against AAV vectors preventing re-administration.

How long does an AAV last?

How long does an AAV last? Adeno-associated viruses (AAVs) are stable for several months to years when stored properly at -80°C.

How long is AAV stable at 4 degrees?

0-iRFP), this study examined the transduction of primary cortical neurons af- ter storage at 4°C for up to 7 weeks. For undi- luted virus (2.1 -5.9 · 10 12 vg/mL), there was up to a 20% loss in transgene expression over 7 weeks at 4°C (Fig. 1a) with a trend of improved but more variable transduction over time.

In what states are air admittance valves legal?

They are not illegal in California as a state because California Plumbing Code allows "Engineered Vent Systems" see Section 911.0.

Where is the best place to put an air admittance valve?

The AAV should be located:
  • Within the maximum developed length permitted for the vent.
  • A minimum of 4 inches above the horizontal branch drain.
  • 6 inches above any insulation material.
  • Within 15 degrees of vertical.

What happens if a soil pipe is not vented?

Foul Odours and Health Concerns

If a soil vent pipe becomes blocked or damaged, foul odours from trapped gases can infiltrate living spaces.

Previous article
What is the efficiency of a standard gas furnace?
Next article
Who do you call to clean your dryer vents?