Journeyman Plumber ExamDrainage, Waste, and Venting (DWV) SystemsEasy
A plumber is designing a DWV system for a multi-story building. Which type of vent pipe extends vertically through the roof and serves as the primary vent for the entire drainage system?
- ARelief vent.
- BLoop vent.
- CStack vent.
- DCircuit vent.
Show answer & explanationAnswer & explanation
Correct answer: C. Stack vent.
The stack vent is the extension of the highest drainage stack above the highest branch interval. It extends through the roof and serves as the main vent for the entire stack and often the primary vent for the building's drainage system.
Why the other options are wrong
- A. A relief vent provides additional air circulation for specific drainage branches or stacks.
- B. A loop vent is a type of circuit vent that loops back to a stack or vent pipe.
- D. A circuit vent serves a battery of fixtures, typically on the same floor.
Stack Vent
The portion of a soil or waste stack that extends above the highest horizontal drainage branch connected to the stack and continues vertically through the roof.
- Primary vent for its drainage stack.
- Terminates above the roof.
- Equal in size to the drainage stack.
- Ensures atmospheric pressure in the drainage system.
Memory trick: Vents have roles, big and small, Stack Vent's the king of them all!