When a plumbing fixture is operated and water drains out of the system, negative pressure causes the valve to open, allowing air to enter as needed to equalize the pressure and protect trap seals from siphoning. When the flow stops, gravity closes the valve, preventing the escape of sewer gases through the valve.
How Studor® Air Admittance Valves Work
- Pressure differential sensitive valve
- Opens when negative pressure occurs in the drainage system
- Admits air into drain, waste & vent system
- Closes to prevent releasing foul air inside
- Will vent up to 20 DFUs
- Use as individual, branch, circuit or stack vent
- Reduces the number of fire-stopping applications
- Should not be exposed to outdoor elements
- No roof penetration if code permits
- Install in vertical upright position not to exceed 15 degress from plumb
- IPS sized
- IPC 2003, IRC 2003, BOCA 1993, code approved
- UPC 301.2, AM&M 2003, code approved
- Proudly made in the USA
Order 6 or more of the PVC or ABS AAV's for greater savings!
Pricing discounts will be shown in the shopping cart.
Sure-Vent® Air Admittance Valves by Oatey®
This air admittance valve features:
- Vacuum sensitive valve
- Opens upon fixture discharge
- Admits air into drain, waste and vent systems
- Closes when pressure differential returns to zeroand remains closed when positive pressure
is present inside the vent system
- No roof penetration where code allows
- Glues into both 1-1/2" and 2" ABS (and threads into 2") - IPS
- Handles up to 15 psi positive pressure
- Should not be exposed to outdoor elements
- Manufacturer recommends at least one vent stack to open air
- Capacity of up to 20 DFUs
- NSF Standard 14
- ANSI/ASSE 1050, 1051
- IAPMO classified mark
- ASTM D2665/D2661
Sure-Vent® air admittance valve = $30.29
Order 6 or more of the same item for greater savings!
Pricing discounts will be shown in the shopping cart.
1-1/2" IPS Auto Trap Vent
This auto trap vent features:
- Replaces any secondary plumbing vent protecting the traps of kitchen sinks, bathroom basins, tubs, showers, washing machines, etc.
- Breaks the siphoning action caused by draining water, preventing sewer gas from escaping the drain
- Used in places where venting through the roof is not possible
- Operates mechanically with a rubber diaphragm
- Install in vertical position
- Some call this mechanical vent a "check vent"
- View installation examples
1-1/2" Mipt Auto Trap Vent = $3.83
Please note: this auto vent trap is not code in many areas due to the potential deterioration and deformation of the rubber seal allowing sewer gases to enter the dwelling.
STUDOR® Maxi-Filtra™
The STUDOR™ Maxi-Filtra ™ operates as a two way vent, which filters air in both directions. Its active carbon filter is designed to eliminate bad odors produced by the plumbing drainage system.
The Maxi-Filtra ™ is for outdoor use only, particularly for use with septic systems, but can also be installed on existing open vent pipes and in systems in which air admittance valves (AAVs) are installed.
This vent pipe filter features:
- Outdoor use only
- Since the Maxi-Filtra™ filters incoming or outgoing air it can be installed vertically or horizontally
- Contains a carbon filter that can last up to two years
- Fits 3" or 4" pipe (IPS), 3" requires No-Hub coupling sold separately below
- Not sure what size pipe you have? View our pipe size info page
Pricing discounts will be shown in the shopping cart.
Ayrlett® Ayr-Filter™
The Ayr-Filter™ is an activated carbon filter that generally helps eliminate offensive odors from building vents and septic systems. The filter is easy to install and requires no special tools, permits, or certifications.
This vent pipe filter features:
- This vent pipe filter is perfect for septic systems and open vents (existing or new builds)
- UV resistant PVC housing
- No special tools required
- Install in vertical upright position only
- Designed for outdoor use
- Activated carbon filter cartridge lasts up to 2 years
- Connection size: 4" spigot (requires 4" coupling to attach to 4" pipe)
- View dimensions / specifications
- Not sure what size pipe you have? View our pipe size info page
Pricing discounts will be shown in the shopping cart.
We also offer a huge selection of PVC fittings and flexible connectors.
P.A.P.A™ - Positive Air Pressure Attenuator by Studor®
This Positive Air Pressure Attenuator (PAPA) features:
- Air pressure equalizer for high-rise drainage systems
- Protects against positive vent stack air pressure in mid to high rise building structures - four floors or higher
- When used in conjunction with the Maxi-Vent™ this combination provides complete protection from positive and negative pressures in a drainage system
- When installed as a complete engineered system no vent stacks are required to vent through the roof, no matter how tall the building, reducing roof leak potential
- Reduces conventional vent piping and saves installation and material costs
- By reducing the need for vent piping through floors the need and cost for fire stop devices is reduced as well as the risk of fire spreading between floors
- Easily retrofits into existing drainage systems to help solve positive pressure problems
- Rated for 5 psi
- P.A.P.A. air capacity per unit: 1 US gallon
- View installation configuration examples
Air flow is just as important in a drainage system as water flow. Longer vertical drainage stack lengths associated with high rise structures can cause a change in air flow to the drainage system. Air flow is essential to maintain proper trap seals which keep smell and sewer gases from entering into living or working spaces. Pressure transients are waves of pressure within a drainage system caused by positive or negative air flow. Negative air transients are capable of sucking water out of trap seals and positive air transients are capable of forcing air through the trap water seal. The Positive Air Pressure Attenuator (PAPA) acts as an air expansion tank to absorb positive air pressures to balance the drainage venting system.
P.A.P.A. Positive Air Pressure Attenuator = $429.49
Drainage Fixture Units
(common plumbing fixtures) |
| Plumbing Fixtures, Appliances |
Minimum Size
Trap/Trap Arm |
Private |
Public |
| Bar Sink |
1-1/2" |
1 |
2 |
| Bathtub or Combination Tub/Shower |
1-1/2" |
2 |
2 |
| Bidet |
1-1/4" |
1 |
-- |
| Bidet |
1-1/2" |
2 |
-- |
| Clothes washer - domestic, standpipe |
2" |
3 |
3 |
| Drinking Fountain or Water Cooler |
1-1/4" |
0.5 |
0.5 |
Kitchen Sink - domestic
(with or without disposer, dishwasher, or both) |
1-1/2" |
2 |
2 |
| Lavatory |
1-1/4" |
1 |
1 |
| Lavatory - in sets of 2 or 3 |
1-1/2" |
2 |
2 |
Laundry Tray
(with our without clothes washer discharge) |
1-1/2" |
2 |
2 |
| Shower, single head, single trap |
2" |
2 |
2 |
| Shower, multi-head, each additional |
2" |
1 |
1 |
| Urinal, integral trap, 1.0 gpf or greater |
2" |
2 |
2 |
| Urinal, exposed trap |
1-1/2" |
2 |
2 |
| Water Closet, 1.6 gpf - tank - gravity |
3" |
3 |
4 |
| Water Closet, 1.6 gpf - flushometer valve |
3" |
3 |
4 |
| Water Closet, greater than 1.6 gpf - tank - gravity |
3" |
4 |
6 |
| Water Closet, greater than 1.6 gpf - flushometer valve |
3" |
4 |
6 |
Please Note: This partial list was taken from the 2012 Uniform Plumbing Code. A complete listing of plumbing fixtures and appliances and their fixture unit values can be found in Chapter 7 of the Uniform Plumbing Code (UPC) book
We recommend plumbing your vents to the outside per your local codes. Using the above-mentioned vents may not be code approved in all areas. Before purchasing and installing any of these above auto-vent products please check with your local codes to determine if acceptable in your area. Please note that all brands of mechanical devices such as AAV's will ultimately fail.
Please note: While we strive to ensure every product we label as "Made in the USA" really is 100% made in the USA, it is also important to understand that sometimes manufacturers make changes to their products, or for various reasons may receive components or materials that they would normally purchase domestically from an overseas supplier - and they don't necessarily let distributors (like us!) know that they've changed something about the product or where it is manufactured.
If you receive a product that PlumbingSupply.com® says is "Made in the USA" and the product states it was manufactured elsewhere, please contact us. We will happily replace or refund your purchase to your satisfaction.
Frequently Asked Questions
Q. "I see that all of your AAV's (auto-vents or air admittance valves) shown on this page are mounted from the top going down (vertically mounted). Can I install any of these AAV's horizontally instead?"
A. To our knowledge, all of the auto-vents (AAV's) that we offer need to be installed vertically to operate correctly and safely.
Q. "What does DFU stand for?"
A. DFU stands for Drainage Fixture Unit. Each plumbing fixture or appliance is assigned a particular drainage fixture unit value as determined by the International Association of Plumbing and Mechanical Officials (IAPMO). For example a kitchen sink is assigned 2 fixture units, but a bathroom sink is assigned 1 fixture unit. Drainage fixture units are used by plumbers and engineers to determine the size of piping needed for proper drainage and vent systems. A listing of plumbing fixtures and appliances and their fixture unit values can be found in Chapter 7 of the Uniform Plumbing Code (UPC) book.
Q. "Can I use Air Admittance Valves (AAVs) only for my whole house?"
A. No, a minimum of one vent must be open to the atmosphere (outside the dwelling) to allow the release of positive pressure in the drain system to prevent possible trap blowout allowing sewer gas into the home/building. A wet vent may also be an option; however, as always, check with your local code enforcement agency to ensure that your project will comply with code in your area.
Q. "How does an Air Admittance Valve work?"
A. An Air Admittance valve is a one-way valve designed to allow air to enter the drainage system when the pressure in the plumbing system is less than the atmospheric pressure. They are designed to close when there is internal drain pressure to prevent any foul odor or gas from releasing out through the air admittance valve and entering your building.
The Air Admittance Valve must be installed a minimum of 4" higher than the trap as required by code. Installing the air admittance valve lower than 4" above the trap can cause drain waste to come in contact with the internal diaphragm. Drain waste contact with the diaphragm can cause debris to become lodged in the diaphragm preventing it from sealing properly and allowing sewer gas and foul odor into the building.
As water flow subsides in the drain the air entering the drain from the Air Admittance valve flows above the water towards the trap weir effectively stopping the water flow. This keeps the trap from being siphoned dry which would allow sewer gas and smell from entering the building. If the Air Admittance valve is installed below the trap, air would not be able to stop the siphoning action of the natural water flow and the trap would be siphoned dry.
See image below for sample diagram:
Q. "What does intumescent mean?"
A. Intumescent is a swelling process. The pad on the back of the fire rated box is made of a material that will swell up when heated helping to protect the box, and hopefully prevent a fire penetrating through the box into the other side of the wall during a fire.
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