Which statement best describes loop vent?

Which statement best describes loop vent?

• A. It vents only a single fixture
• B. It is used to relieve pressure on the main sewer line
• C. It is connected to the stack vent and is usually located on the top floor
• D. It is located inside a cabinet near fixtures

Answer: (C)

A loop vent provides a path from a fixture’s drain up to the building’s vent stack, allowing air to enter the drain as wastewater flows. This helps prevent the trap from being siphoned and keeps drainage flowing smoothly. Because it must connect to the vent stack, it’s typically installed on or near the top floor to ensure a proper vertical rise to the vent system. It isn’t meant to relieve pressure on the main sewer line, and it isn’t simply tucked inside a cabinet near fixtures—the important point is its connection to the stack vent and its top-floor placement.

A loop vent provides a path from a fixture’s drain up to the building’s vent stack, allowing air to enter the drain as wastewater flows. This helps prevent the trap from being siphoned and keeps drainage flowing smoothly. Because it must connect to the vent stack, it’s typically installed on or near the top floor to ensure a proper vertical rise to the vent system. It isn’t meant to relieve pressure on the main sewer line, and it isn’t simply tucked inside a cabinet near fixtures—the important point is its connection to the stack vent and its top-floor placement.