Most people know about hot and cold water supply piping as well as the drain pipework that takes away the waste. But for the drainage system to work properly, there is another network of piping that allows free flow of waste, known as the plumbing vent system.
What Plumbing Vents Do
Unlike supply piping, drain systems have air in them. To keep the sewage pipes at atmospheric pressure so the waste can flow, they must be open to air. In your house, this is achieved using a system of pipes called the venting system.
How it Should be Done (Some Rules)
All fixture drains need to be vented. That means each sink, tub, toilet, and lavatory. Sometimes they can be combined but plumbing codes have rules about which fixtures can be combined and the size of pipe needed for each group.
Pipe size must be correct. This is also dictated by the plumbing code and depends on the plumbing drain size.
The vent stack must be terminated vertically through the roof. It cannot go through a side wall or the scent from the sewage system will enter open windows.
Vent piping must slope upward without dips to allow the sewage gas to escape.
The base of the stack must have a cleanout so any obstructions can be removed if needed.
There’s a maximum distance from the drain point to the vent stack connection point. This distance depends on the drain pipe size and slope. Additionally, fixtures must be connected above the height of the fixtures, or the vent pipe can become filled with water, rendering it ineffective.
Effects of Poor Venting
Poorly vented fixtures will make gurgling noises as the waste attempts to pass through the pipe and air in the pipe has nowhere to go. Bubbles of sewer air will come through the water in the p-traps and you’ll notice the smell.
Water can be siphoned out of the trap, leaving it open for sewer gases to enter your home. This is a health risk and needs to be addressed immediately.
Your waste will drain slowly. This often happens with the gurgling noise as the waste attempts to move along the pipe while pushing air ahead of it (air that’s supposed to exit through the venting system).
It’s Best to Have a Professional
Take Care of it
If you’re having problems with your drainage system and you suspect poor venting, give us a call. If you’re planning to install new fixtures, we can help you ensure that they are properly vented to code so you prevent any of these issues from occurring.