Understanding Plumbing Vents

When you think about plumbing, your mind’s eye probably pictures a bunch of pipes and perhaps some appliances, such as a toilet, sink, and bathtub. There are more aspects to plumbing than just pipes, however, and having proper venting is one of them.

What Are Plumbing Vents?

Plumbing vents, which are also referred to as the venting system, are special pipes that lead from the appliances in your home to an outdoor area. Usually, these vents lead up to the roof, but this is not always the case.

The vents serve a very important purpose for plumbing. Rather than carrying water through the pipes leading to the vents, these pipes carry sewer gases. This way, they are safely removed from your home rather than getting backed up and potentially making you sick.

Plumbing vents also help to bring oxygen into your plumbing system, which assists with the aerobic sewage digestion that is necessary for breaking the waste down. In addition, the vents help maintain the water seals in the plumbing traps, which prevents sewer gases from getting into your home.

Without the help of plumbing vents, water and waste would not move properly through the pipes in your home. This is because the venting helps to maintain neutral air pressure within the drains. As a result, gravity is able to successfully pull the water and waste through the pipes and drains. In addition to having proper venting in place, the pipes must also maintain the proper downward slope throughout the home in order to have the proper flow.

Why Does Neutral Air Pressure Need to Be Maintained?

When water is not flowing through a sewer pipe, the pipe is able to maintain neutral air pressure when compared to its surrounding atmosphere. When waste water moves through the pipe, however, it can act like a piston. The air downstream can become compressed. This creates positive pressure in the pipe. The air upstream can pull a vacuum, and this pulls back on the waste.

The positive pressure in the pipe needs to be released. Otherwise, it will push back against the waste stream. At the same time, there must be air flow behind the waste stream. If there is not, negative pressure will occur and this will result in suction. The volume of the waste that was discharged will determine how much pushing or suctioning takes place.

Since the toilet usually has the shortest trap seal, the suctioning effect that results from excessive negative air pressure can cause the toilet to become completely empty. If the trap is emptied in the toilet, sewer gases will enter into the home.

Do I Need to Have Plumbing Vents?

According to building codes, every appliance in a home must have a trap. In addition, with the exception of a few unique cases, every fixture must also have a vent.

When it comes to plumbing, many people underestimate the importance of having proper venting in place. Without proper venting, the health and comfort of you and your family can be at risk. Therefore, if you are uncertain how to properly install your venting, it is a good idea to hire a professional that can take care of it for you.

Where Do the Plumbing Vents Need to Be Located?

Most codes require a vent stack, which is a pipe that leads to the main roof vent of the system, to be placed somewhere within a five foot radius of the appliance. Therefore, you will need to have a vent within a five foot radius of items such as your sinks, your shower, your bath tub, and your toilet.

Can Plumbing Vents Get Clogged?

It is somewhat common for plumbing vents to become blocked. Ice build up in the winter can cause a clog, as can leaf build up or even the body of a dead animal. If the house is really old, there are often horizontal areas of a vent by a sink the fill with rust. You can tell that a vent has been clogged because you will experience slow drainage or you may see bubbles in your toilet when you flush it. You might hear a strong glugging sound as a fixture drains. Or, your traps may empty all the way and cause gas to escape into your home.

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