How to Make a Plumbing Loop Vent

A plumbing loop vent is a type of venting system that is used to allow air to enter and exit a plumbing system. The main purpose of a loop vent is to prevent Sewer Gas from entering the home through the drains. A loop vent consists of two pipes that are connected together at the top, forming a loop.

One pipe goes from the sewer line to the roof, while the other goes from the drain line back down to the sewer line.

  • Cut a hole in the main drain pipe near the fixture you want to vent
  • Attach a tee fitting to the drain pipe, and then attach a length of pipe to the tee fitting
  • Run the new length of pipe up to the attic or other high point in your home
  • Cut a hole in the roof near where the new pipe will come up through, and install a vent cap on the new pipe
How to Make a Plumbing Loop Vent


How High Does a Loop Vent Need to Be?

A loop vent is a type of mechanical ventilation that is used to help improve the indoor air quality of a home. The way it works is by pulling fresh air from outside and then circulating it throughout the house. One of the benefits of using a loop vent is that it can help to reduce the amount of energy needed to heat or cool the home.

The other main benefit of using a loop vent is that it can help to improve the indoor air quality by reducing the levels of pollutants, such as dust, pollen, and pet dander.

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One thing to keep in mind when installing a loop vent is that it needs to be installed at least four inches above the ground. This will ensure that there is enough clearance for the fresh air intake and exhaust vents.

How Does Loop Venting Work?

Loop Venting is a method of venting that uses a looped pipe to connect the drains of fixtures in order to allow air to enter the drain and prevent negative pressure from building up. This type of venting is often used in situations where it is not possible to run a traditional vent pipe to the outside, or when there are multiple fixtures being vented.

What is the Difference between a Circuit Vent And a Loop Vent?

There are a few key differences between circuit vents and loop vents that are important to understand. Circuit vents, also called individual vents, are installed on the drain line for each fixture in a home. Loop vents, on the other hand, are installed on the main sewer line and serve to vent all of the fixtures in a home.

One of the biggest advantages of circuit vents is that they protect against negative pressure in the drain lines. This can happen when there is a blockage in the main sewer line or when water is being drained from a fixture faster than it can enter the sewer line. The circuit vent prevents this negative pressure from affecting the fixtures by providing an alternate route for air to enter the system.

Loop vents, while they do provide ventilation for all of the fixtures in a home, are not as effective at preventing negative pressure build-up. This is because they are only vented at one point rather than at each fixture. Additionally, loop vents can actually create positive pressure in the system if there is too much airflow going through them.

This can cause problems with fixtures draining properly and may even lead to backups.

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How Far Can a Plumbing Vent Run Horizontal?

There is no definitive answer to this question as it depends on a number of factors, such as the type of plumbing system, the size of the pipes and the layout of the building. However, in general, a plumbing vent can run horizontal for up to 50 feet before it needs to be vented vertically.

Loop Vent Island Loop Vent

Are Loop Vents Legal

A loop vent is a type of mechanical vent that uses a series of small loops to create airflow. Loop vents are commonly used in HVAC systems and are legal in most jurisdictions. However, some code officials consider loop vents to be illegal because they can create backdrafting conditions.


A plumbing loop vent is a type of venting system that helps to prevent odors and sewer gases from entering your home through the drains. It works by creating a watertight seal between the drain and the vent stack, which allows air to flow freely through the system. There are two types of plumbing loop vents: active and passive.

Active vents require a power source, such as an electric fan, to keep the air moving through the system. Passive vents rely on gravity to keep the air moving.

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