Plumbing vents are an essential component of any plumbing system, but many homeowners may not fully understand their purpose and importance. If you’ve ever wondered about the different types of plumbing vents and what they actually look like, you’ve come to the right place.
In this article, we’ll explore the various types of plumbing vents and provide a visual guide to help you identify them. From understanding the benefits of using a plumbing vent to choosing the right type for your home, we’ll cover it all.
21 most common types of plumbing vents
1. Soil stack vent
This is a vertical pipe that extends through the roof of a building. It is typically made of cast iron or PVC and is larger in diameter than other vents. The soil stack vent is connected to the main sewer line and allows air to enter the drainage system.
2. Vent stack
Similar to the soil stack vent, a vent stack is a vertical pipe that protrudes through the roof. It is usually smaller in diameter than the soil stack vent and serves to vent multiple fixtures in a building, such as sinks, toilets, and showers.
3. Air admittance valve (AAV)
An AAV is a mechanical device that serves as a vent for individual fixtures. It is often used as an alternative to traditional venting methods when a vertical vent stack is not feasible. AAVs are typically small, round devices that can be installed under sinks or inside walls.
4. Horizontal vent
A horizontal vent is a pipe that runs horizontally and connects to the drainpipe. It is used when a fixture is located too far from a vertical vent stack. Horizontal vents are usually smaller in diameter than vertical vents and are installed with a slight slope to allow proper airflow.
5. Island vent
Island vents are used in kitchen islands or other fixtures that are not against a wall. They are similar to air admittance valves and are installed beneath the fixture. Island vents typically have a sleek and compact design.
6. Relief vent
A relief vent is a short vertical pipe that connects to a horizontal drainage pipe. It is used to prevent siphoning and to equalize air pressure in the drainage system. Relief vents are usually small in size and may be located near fixtures such as bathtubs or washing machines.
7. Combination vent
As the name suggests, a combination vent combines the functions of a vent stack and a drainpipe. It is a dual-purpose pipe that carries both waste and vent gases. Combination vents are often used in small-scale plumbing systems where space is limited.
8. Circuit vent
A circuit vent is a vent pipe that serves multiple fixtures connected in a loop or circuit. It is typically installed near the last fixture in the circuit and connects to the main vent stack or stack vent. Circuit vents help to prevent trap siphonage and maintain proper air circulation.
9. Stack vent/stack extension
A stack vent or stack extension is an additional vertical pipe that is added to an existing vent stack. It is used when the original vent stack is not tall enough to provide adequate venting. Stack extensions are installed above the roofline and help improve the overall venting capacity of the plumbing system.
10. Crown vent
A crown vent is a type of vent that is integrated into the building’s roofline. It consists of a short pipe with a vent cap that extends horizontally from the roof, allowing air to enter the plumbing system. Crown vents are commonly used in situations where traditional roof penetrations are not desired or possible.
11. Relief vent extension
A relief vent extension is a vertical pipe that is connected to a relief vent. It is used to extend the height of the relief vent to meet local code requirements. The extension pipe is typically smaller in diameter than the relief vent and is installed above the roofline.
12. Combination waste and vent system
In some plumbing systems, a combination waste and vent system is used. This system combines the waste and vent functions into a single pipe. The pipe serves as both a drain for wastewater and a vent to allow air to enter the system. Combination waste and vent systems are often used in smaller buildings or where space is limited.
13. Wet vent
A wet vent is a vent pipe that also serves as a drain for one or more fixtures. It allows wastewater to flow through the vent pipe while providing the necessary ventilation. Wet vents are commonly used in bathroom groups where multiple fixtures (such as a toilet, sink, and bathtub) are connected to a single vent.
14. Dilution vent
A dilution vent is used in commercial or industrial settings where harmful or noxious gases need to be diluted before being released into the atmosphere. It is typically a large-diameter vent pipe that helps to disperse and dilute the gases with a greater volume of fresh air.
15. Forced vent
A forced vent is a mechanical device that uses a fan or blower to assist in venting the plumbing system. It is often employed in situations where natural venting is insufficient due to long horizontal runs or complex plumbing layouts. Forced vents help to ensure proper air circulation and prevent the buildup of sewer gases.
16. Combination drain and vent system
In some plumbing configurations, a combination drain and vent system is used. This system combines the drain and vent functions into a single pipe. The pipe allows for the discharge of wastewater while also providing venting to maintain air pressure balance within the system.
17. Individual fixture vent
An individual fixture vent is a dedicated vent pipe that serves a single fixture. It provides direct venting for that particular fixture, allowing proper air circulation and preventing negative pressure within the plumbing system. Individual fixture vents are commonly used for fixtures such as sinks, showers, and toilets.
18. Yoke vent
A yoke vent, also known as a common vent, is a single vent pipe that serves two adjacent fixtures. It is a shared vent that connects to both fixtures, providing venting for both drains. Yoke vents are often used in bathroom setups where fixtures like a sink and a bathtub or a sink and a shower are located side by side.
19. Cheater vent
A cheater vent, also called an inline vent or an air admittance valve, is a small mechanical valve installed on a drainpipe below a fixture. It serves as a venting solution when a traditional venting method is not feasible. Cheater vents open and allow air to enter the system when there is a negative pressure, but remain closed otherwise to prevent the escape of sewer gases.
20. Roof vent
A roof vent is a vent pipe that extends through the roof to allow for proper venting and the release of sewer gases. It is commonly used in residential and commercial buildings to vent fixtures located below the roofline. Roof vents can be connected to various parts of the plumbing system, such as drainpipes or vent stacks.
21. Grease waste vent
A grease waste vent is specifically designed for plumbing systems that handle grease waste from commercial kitchens or food processing areas. It is typically a large-diameter vent pipe that accommodates the high volume of grease-laden wastewater and helps prevent the accumulation of grease within the system.
What’s the purpose of using a plumbing vent?
The main purpose of using a plumbing vent is to maintain proper air pressure and ensure efficient drainage within the plumbing system.
Vents allow fresh air to enter the system, preventing the formation of vacuum or positive pressure conditions that can impede the flow of wastewater.
By equalizing air pressure, vents also help to prevent sewer gases from entering the building, ensuring a safe and odor-free environment.
How to choose the right type of plumbing vent for your home?
When choosing the right type of plumbing vent for your home, there are several factors to consider.
First, familiarize yourself with local building codes and regulations to understand any specific requirements or restrictions.
Assess your plumbing system layout, including the location and number of fixtures, distances between fixtures and the main drain line, and available space for vent installation.
Consider the type of fixtures you have, as certain fixtures may require dedicated vents.
Consult with a professional plumber who can evaluate your plumbing system, recommend suitable venting options based on code compliance and efficiency, and ensure proper installation to meet your specific needs.
Which type of plumbing vent is easiest to maintain?
Among the different types of plumbing vents, air admittance valves (AAVs) are generally considered the easiest to maintain.
AAVs are mechanical devices that eliminate the need for extensive vent pipe systems.
They are typically installed under sinks or within walls, making them easily accessible for maintenance or replacement.
AAVs have a simple design, require no external venting to the roof, and are equipped with self-sealing mechanisms that prevent the escape of sewer gases.
Their compact size and straightforward installation make AAVs a convenient option for homeowners seeking a low-maintenance plumbing vent solution.
Pros and cons of each of these plumbing vents
| Plumbing Vent Type | Pros | Cons |
|---|---|---|
| Soil Stack Vent | Effective venting for the entire plumbing system | Requires larger pipe size and vertical installation |
| Vent Stack | Provides venting for multiple fixtures | Requires vertical installation and roof penetration |
| Air Admittance Valve (AAV) | Easy to install, no need for roof vent | May require periodic maintenance or replacement |
| Horizontal Vent | Allows venting in situations with limited vertical space | Can be prone to clogging or inadequate venting |
| Island Vent | Suitable for fixtures not against a wall | Limited capacity and may require additional vents |
| Relief Vent | Prevents siphoning and equalizes air pressure | Requires proper placement and sizing for effectiveness |
| Combination Vent | Combines waste and vent functions in one pipe | Limited to smaller-scale plumbing systems |
| Circuit Vent | Cost-effective for venting multiple fixtures in a loop | Requires proper design and sizing for optimal performance |
| Stack Vent/Stack Extension | Enhances venting capacity in situations with insufficient height | Requires additional roof penetrations and may affect aesthetics |
| Crown Vent | No need for roof penetrations or additional vent pipes | Limited to specific architectural designs or building types |
| Relief Vent Extension | Helps meet local code requirements for relief vent height | Requires proper sizing and installation for effective venting |
| Combination Waste and Vent | Efficient use of space, suitable for smaller buildings | Requires careful planning to ensure proper drainage and venting |
| Forced Vent | Assists venting in complex plumbing layouts or long horizontal runs | Requires mechanical components and potential maintenance |
| Individual Fixture Vent | Dedicated venting for each fixture, effective in preventing trap siphonage | Requires additional vent pipes for each fixture |
| Yoke Vent | Shared venting for adjacent fixtures, cost-effective | Limited to specific fixture arrangements and distances |
| Cheater Vent | Convenient alternative to traditional venting methods | May require periodic maintenance and proper installation |
| Roof Vent | Common and traditional venting method for various fixtures | Requires roof penetrations and maintenance to prevent leaks |
| Grease Waste Vent | Specifically designed for efficient venting of grease waste | Limited to commercial kitchens or food processing facilities |
| Wet Vent | Efficient use of space, combines drain and vent functions | Requires proper sizing and adherence to plumbing code regulations |
| Dilution Vent | Dilutes harmful gases before release into the atmosphere | Limited to specific commercial or industrial settings |
| Mechanical Ventilation | Provides controlled ventilation for the entire plumbing system | Requires mechanical components and ongoing maintenance and monitoring |
| Studor Vent | Compact and easy to install, eliminates need for roof vent | Limited capacity and may require periodic maintenance or replacement |
| Loop Vent | Cost-effective solution for venting multiple fixtures | Requires careful planning and coordination to ensure proper venting |
| Branch Vent | Provides individual venting for branch lines | Requires proper sizing and design to prevent inadequate venting or drainage |
Which type of plumbing vent gets the fewest clogs?
Air admittance valves (AAVs) are generally less prone to clogging compared to other types of plumbing vents.
AAVs typically have a simple design with no moving parts, reducing the likelihood of debris accumulation or blockages.
AAVs are often installed in easily accessible locations, such as under sinks or within walls, allowing for periodic inspection and potential cleaning if necessary.
Proper installation, adherence to manufacturer guidelines, and regular maintenance are still crucial to ensuring the optimal performance and longevity of AAVs, as any vent can potentially experience clogging if not properly maintained.
Which plumbing vents go out through the roof vs. the walls?
Plumbing vents that go out through the roof are typically soil stack vents, vent stacks, stack extensions, crown vents, and relief vents.
These vents are designed to extend vertically above the roofline to provide proper venting and prevent the entry of sewer gases into the building.
On the other hand, plumbing vents that go out through walls include air admittance valves (AAVs) and cheater vents, which are often installed beneath sinks or within walls as an alternative to traditional roof venting methods.
These wall-mounted vents allow for proper air circulation and venting without the need for roof penetrations.
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