The Purpose Of The Plumbing Vent Pipe And Why You Should Keep It Clean

One of the most important plumbing pipes in the home doesn’t carry water it carries air. I am talking about the plumbing vent line. The piping that goes out from the house to the sewer line is called the drain, waste vent system, or DWV. This pipe provides for the outflow route of water from sink drains, plus waste from toilet. The vent line is responsible for maintaining stable air pressure in the outflow pipe, which has important implications.

When drains are not in use, they are full of air. At the far end of the drains, in the sewer, there is likewise lots of air. But this air, in the sewers, is foul and must be prevented, at all costs, from refluxing into the house. The plumbing fixture that prevents this from happening is the “plumbing trap.” Plumbing traps are “P” or “S” shaped curved sections of the outflow drain that contain water in the curved bottom of the segment. They can be seen below the sink. The water, which collects in the curved segment of the pipe prevents reflux of sewer gases. A crucial function! When the sink drains, the newly draining water pushes the old water out of the trap and down the pipe and some of the newly draining water takes its place and will now fill the curved part of the plumbing trap and protect the house from the entrance of sewer gas.

But there is another danger we need to consider when thinking about air fluxes in the drain system. As the bolus of water flushes down the drain from the toilet, sink tub or shower, it pushes the air in the drain system before it and out the pipe. This subsequently creates a reduced air pressure in the pipe slightly beyond the water trap. If nothing is done about this reduced pressure, it will serve to pull water out of the trap through a siphoning effect, and allow sewer gas to pass into the house.

This dangerous event is prevented from occurring by the plumbing vent pipe. The vent pipe leaves the drain in a perpendicular direction, and through a series of parallel connections, rises to the roof and exits form the roof through the tiny vent tube that I described above. When air pressure in the drain system lowers, than air is sucked into the house through this vent pipe, and that equalizes the air pressure in the drains, and prevents backflow of sewer gases.

The air vent system works marvelously to prevent dangerous pressure changes in the pipe system, except when the roof vent pipe gets clogged by dead animals, ice, snow, or leaves. Sometimes air vents get clogged. They may be clogged by ice, snow, dead animals, or leaves. When this happens, the air fails to equalize in the system and the householder will begin to hear a strange gurgling sound in this drains, which actually corresponds to the siphoning taking place as water is pulled out of the traps. When a home owner hears this sound, he must call a plumber to clean out the vent, as the entrance of sewer gas can be dangerous.

Thanks to A-1 Plumbing of Baltimore a Baltimore plumbing company, for sponsoring this article on plumbing air vents.

Shortcut to helpful things to know about suspended ceiling – study the web site. The times have come when proper info is really only one click away, use this chance.