Journeyman Plumber ExamDrainage, Waste, and Venting (DWV) SystemsHard
A plumber is installing a relief vent for a horizontal branch drain that serves multiple fixtures. From what point on the branch drain must the relief vent be connected?
- AThe upstream end of the branch
- BThe last two fixture connections
- CThe farthest downstream fixture connection
- DThe midpoint of the branch
Show answer & explanationAnswer & explanation
Correct answer: B. The last two fixture connections
A relief vent is typically required for long horizontal branch drains serving multiple fixtures. It must connect to the horizontal branch drain between the two most downstream fixture connections to effectively prevent trap siphonage and backpressure for those fixtures.
Why the other options are wrong
- A. Connecting at the upstream end would not provide adequate relief for fixtures further downstream.
- C. Connecting at only the farthest downstream fixture connection might not protect the second to last fixture.
- D. Connecting at the midpoint is arbitrary and does not target the critical area for relief venting.
Relief Vent Placement
A type of vent that provides additional air circulation for long horizontal branch drains, specifically positioned to protect the most vulnerable fixtures.
- Used for long, heavily loaded branch drains.
- Prevents siphoning and backpressure.
- Specific connection point relative to downstream fixtures.
Memory trick: Vents Vary, Vital for Flow.