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Auto Vents - Air Admittance Valves - Home Sewer Vents


PlumbingSupply.com® offers auto vents, vent filters, and air admittance valves in various styles and installation types. An air admittance valve may sometimes be used as an alternative to extending a vent through the roof or sidewall to the open atmosphere. Click here for more information.

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Air Admittance Valves by STUDOR®


Mini-Vent air admittance valves

Maxi-Vent air admittance valves
These air admittance valves feature:
  • Pressure sensitive valve: as fixture drains, negative pressure in the drainage system opens one-way valve, drawing air through the valve to cut off the water flow and prevent trap siphoning
  • Admits air into drain, waste and vent systems
  • Closes to prevent foul air or gasses inside
  • Can be used as individual, branch, circuit or stack vent
  • Architectural designs no longer hinder plumbing ideas
  • Reduces the number of fire-stopping applications since vent piping through walls and ceilings will not be needed
  • Exclusive vermin protection system
  • Limited lifetime warranty for replacement of defective valves
  • Limited outdoor use if protected from the elements
  • Considered "the standard" by some
  • Multiple roof vent penetration is reduced; only one vent needs to extend to the open atmosphere for each building drainage system
  • Sized for IPS pipe
  • Mini-vent can vent up to 24 drainage fixture units (DFU) on a 2" vertical stack - view sizing guide chart
  • Maxi-vent can vent up to 500 drainage fixture units (DFU) on a 4" vertical stack - view sizing guide chart
  • Mini-vents and Maxi-vents must be installed vertically - they require gravity to close when the atmosphere inside the pipe stabilizes after a drain discharge
  • NSF Standard 14
  • ASSE 1051, 1050 rated
  • IAMPO Classified Marking
  • Always check with local code officials for any possible restrictions
  • View drainage fixture unit (DFU) chart for common plumbing fixtures
Mini-Vent - view Mini-Vent dimensions Price & Quantity
Mini-Vent® for 1 1/2" or 2" pipe - each $29.21
Mini-Vent® for 1 1/2" and 2" pipe - with protective cover $31.19
 
Maxi-Vent - view Maxi-Vent dimensions Price & Quantity
Maxi-Vent® for 3" or 4" pipe (vent stack) - each
- includes insulating cover and 4" push-fit connector
$44.58
3" No-Hub Coupling needed for use on a 3" pipe $5.74

Order quantities of 6 or 36 of the same item for greater savings!
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Mini-Vent Sizing Guide
Horizontal Branch Size Maximum DFU's
1 1/2" 3
2" 6
3" 20
4" 160
Vertical Stack Size Maximum DFU's
1 1/2" 8
2" 24
Maxi-Vent Sizing Guide
Horizontal Branch Size Maximum DFU's
3" 20
4" 160
Vertical Stack Size Maximum DFU's
3" 72
4" 500




STUDOR® Maxi-CAP for Maxi-Vents shown above


STUDOR Maxi-Cap
The Aluminum STUDOR® MAXI-CAP is specifically designed to protect MAXI-VENTS® from damaging UV rays and temperature extremes when installed outdoors. This aluminum Maxi-CAP fits on top of the insulating cover included with the Maxi-Vent.

Prior to installing a Maxi-Vent, Maxi-Cap can be painted to match roof color for aesthetics.   View Maxi-CAP dimensions

Maxi-CAP UV protective cap for Maxi-Vents = $23.76

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Redi-Vent Air Admittance Valves by STUDOR®

Want to add a sink but running a vent through the roof is a problem?

These air admittance valves feature:
  • One-way valve keeps smell and mixtures of methane, carbon dioxide, nitrous oxides, and sulfur dioxide gases from entering into the home from the sewage system yet allows fresh air to enter into drain to stop p-trap siphoning
  • An alternative solution to extending a vent through the roof or sidewall; these air admittance valves simplify drainage and waste venting by eliminating expensive roof penetration and vent piping (when building authority allows)
  • Every building system must have at least one vent extend to the open atmosphere
  • Screening on the inside and outside of the valve helps protect the sealing assembly from insects and debris
  • The compact design is perfect for tight applications
  • Redi-Vent valve fits 1-1/2" and 2" pipes
  • Tubular Tee WITH Redi-Vent fits 1-1/2" OD tubular pipes
  • Can be used for residential or commercial installations
  • Allows sinks to be used in architecturally challenging room designs prohibiting normal venting through the roof (but must check local codes for actual approval)
  • Redi-Vent® must be installed vertically - gravity is used to close it when the atmosphere inside the pipe stabilizes after a drain discharge
  • Ideal for venting single fixtures, kitchen sinks, bathroom sinks or bathroom groups up to 20 drainage fixture units (DFU)
Redi-Vent Sizing Guide
Horizontal Branch Size 1 1/2"    2"      3"  
Maximum DFU 3 6 20

Description Price & Quantity
Redi-Vent Air Admittance Valve Only - PVC - view Redi-Vent dimensions $24.29
Redi-Vent Air Admittance Valve Only - ABS - view Redi-Vent dimensions $24.28
1-1/2" OD PVC Tubular Tee WITH Redi-Vent Air Admittance Valve
- view tubular tee with Redi-vent dimensions
$28.98

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View our drainage fixture unit (DFU) chart for some common plumbing fixtures


Fire Rated AAV Recessed Box by STUDOR®

Fire Rated Recessed Vent Box
This recessed box feature:
  • Ideal for in wall installations of the Mini-Vent and Redi-Vent
  • The small, low profile box is easy to install and contains a sleek grille for a clean finish
  • One piece box and mounting flange design needs no additional framing or support when installed to the stud bay
  • Useful alternative when the air admittance valve cannot be installed in an existing cabinet
  • Made from special flame resistant resin with an intumescent pad installed on the back of box
  • Connects to 1-1/2" or 2" ABS or PVC vent pipe
  • View dimensions

AAV Fire Rated Recessed Outlet Box = $56.26

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Mini Recess Box by Studor® For Mini-Vent

Studor mini recess box and grille
This mini recess box features:
  • Allows recessing of the Mini-Vent in the wall in a finished box
  • Designed for indoor use only
  • Hidden, yet accessible if servicing is ever needed
  • View dimensional drawing

Studor® Mini Recess Box with grill and screws - for Mini-Vent = $14.92

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Tec-Vent Air Admittance Valves by Studor®

Tec-Vent by Studor
This Tec-Vent air admittance valve features:
  • Flame retardant polycarbonate resin constructed with silicone membrane
  • One-way valve keeps sewer gases and bad odors from entering into the building from the sewage system yet allows fresh air to enter into p-trap to prevent trap seal siphoning
  • For commercial or residential drainage venting systems
  • UV inhibited and rated for outdoor use
  • Vacuum sensitive valve; opens upon fixture discharge
  • Admits air into drain, waste and vent systems to stop trap siphoning
  • Must be installed vertically - gravity causes it to close when pressure differential returns to zero and remains closed when positive pressure is present inside the vent system
  • Less roof vent penetrations needed where code allows
  • 1-1/2" Mipt pipe connection
  • Manufacturer recommends at least one vent stack to open air
  • Capacity of up to 160 drainage fixture units (DFUs) on a 4" horizontal branch
    - view sizing guide charts
  • Tec-Vent may be installed on sewage ejection systems with prior local code approval and when installed according to engineer design specifications
  • Listed with: ANSI/ASSE 1050, 1051; NST 14; UL Standard 2043

Studor® Tec-Vent air admittance valve = $39.39

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Tec-Vent Drainage Fixture Unit (DFU) Sizing Guides

Horizontal Branch Size Maximum DFU's
1 1/4" 1
1 1/2" 3
2" 6
3" 20
4" 160
Vertical Stack Size Maximum DFU's
1-1/2" 8
2" 24

View our drainage fixture unit (DFU) chart for some common plumbing fixtures


Chem-Vent Air Admittance Valves by Studor®

Tec-Vent by Studor
This Chem-Vent air admittance valve features:
  • Designed specifically for chemical acid waste systems
  • Flame retardant polypropylene resin constructed to conform to ASTM D-4101
  • One-way ball valve type seal using EPDM o-ring allows fresh air to enter into fixture p-trap to prevent trap seal siphoning and keeps chemicals, sewer gases and bad odors from entering into the building from the waste system
  • 1-1/2" Schedule 40 male (spigot) pipe for direct connecting into any FR-PP (flame retardant polypropylene) fittings
  • Installs into mechanical joint fittings, electrofusion FR-PP (flame retardant polypropylene), and adaptable to CPVC, glass, PVDF or Duriron® piping.
  • Chemical waste systems must be designed by chemical drain professionals and Studor manufacturer must be consulted for proper installation guidelines for chemical compatibility
  • Manufacturer recommends at least one vent stack extends to open air
  • Chem-Vents should be installed in accessible locations
  • Must be installed vertically - closes by gravity when pressure differential inside the pipe returns to zero and remains closed when positive pressure is present inside the vent system
  • Capacity of up to 6 drainage fixture units (DFUs) on a 2" horizontal branch
  • Chem-Vent may be installed in non-neutralized chemical waste systems when the system is designed by a design professional
  • Valve is screened on inside and outside to protect seal assembly from possible debris or insect intrusion
  • View Chem-Vent dimensions
  • Meets performance standards for: ASSE 1051, 1049; NSF 14

Chem-Vent Drainage Fixture Unit (DFU) Sizing Guide

Horizontal Branch Size Maximum DFU's
1-1/2" 3
2" 6

Studor® CHEM-VENT air admittance valve = $109.97

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How Studor® Air Admittance Valves Work

Studor venting
Studor sealed
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

Auto Vent
  • 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 USA flag button

Description Price & Quantity
PVC - AAV - 2" or 1-1/2" solvent x 1-1/4" male threaded adapter $19.95
ABS - AAV - 2" or 1-1/2" solvent x 1-1/4" male threaded adapter $19.98

Order 6 or more of the PVC or ABS AAV's for greater savings!

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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 zero
    and 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

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1-1/2" IPS Auto Trap Vent

autovents for mobile homes
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.


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STUDOR® Maxi-Filtra

STUDOR Maxi-Filtra vent pipe filter
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
Description Price & Quantity
Maxi-Filtra air vent filter for 3" or 4" pipe
Order 6 or more of the same item of the same item for greater savings!
$46.69
Replacement cartridge for Maxi-Filtra Studor
Order 6 or more of the same item for greater savings!
$13.03
3" No-Hub Coupling needed for use on a 3"pipe $5.74

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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.
ayr-filter activated carbon filter
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
Description Price & Quantity
Ayr-Filter air vent filter
Order 6 or more of the same item for greater savings!
$29.97
Replacement cartridge for Ayr-Filter
Order 6 or more of the same item for greater savings!
$9.87
PVC coupling - 4" (SxS) $5.38
Flexible connector for 4" pipe $9.65

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We also offer a huge selection of PVC fittings and flexible connectors.

P.A.P.A - Positive Air Pressure Attenuator by Studor®

positive air pressure attenuator
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

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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:
Air admittance valve 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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