Plumber Red Seal · Question
According to the National Plumbing Code (NPC), when circuit venting a branch serving eight water closets, what is the minimum required size of the circuit vent?
For a circuit-vented branch with a hydraulic load from more than four water closets, the NPC requires the circuit vent to be not less than 3 inches in size. The
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Question: According to the National Plumbing Code (NPC), when circuit venting a branch serving eight water closets, what is the minimum required size of the circuit vent?
Answer options:
- 2 inches ✅ 3 inches
- 4 inches
- Equal to the size of the branch drain
Correct answer: 3 inches
Explanation: For a circuit-vented branch with a hydraulic load from more than four water closets, the NPC requires the circuit vent to be not less than 3 inches in size. The vent size is based on the number of fixtures, not the size of the drain itself.
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