In your cottage’s plumbing system, the vents maintain a pressure balance that lets liquids flow down the drain, while the traps block sewer gas from coming back up into the air you breathe.
Every time you use a sink, the liquid in the trap below is replaced with new water. If the drain isn’t adequately vented, this rush of water can suck the trap dry—and sewer gas can then escape.
In many renovations—such as adding a laundry room or a kitchen island with a sink—connecting new plumbing fixtures to a vent that exits through the roof is difficult. That’s where a modern cheater vent—properly called an air admittance valve (AAV)—comes in handy as an alternative method of getting air safely into the drain.
When water flows through the drain, it creates negative pressure, which opens a diaphragm in the AAV to admit room air into the drain. Once the water stops flowing, the negative pressure ends, and the AAV instantly closes so sewer gases can’t escape.
A properly installed AAV meets Canada’s National Plumbing Code, and it’s reliable and maintenance-free. There is, however, an older type of cheater vent with a spring-loaded gasket mechanism that can fail. They’re generally not permitted any more.
Cheater vents should be installed where they are accessible so they can be replaced. If a drain is gurgling and slow, or it smells like a sewer, there could be an automatic air vent that needs attention.
This article was originally published in the August 2024 issue of Cottage Life.
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