Vent on the wrong side of the trap

Plumbing · Venting Systems · printed page 292 (PDF page 293)

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Book index entries

Venting – Plumbing – on Wrong Side of Trap Plumbing

Text in the illustration

vent
slope
sewer gas
basin
slope 1/4" per ft.
stack

Generated explanation

The illustration shows a basin drain connected through a trap to a horizontal branch leading to a vertical stack. A vent rises from the fixture side of the trap and runs back to the stack above the drain connection. A red prohibition symbol marks this vent arrangement as incorrect because the vent connects on the wrong side of the trap. Black arrows show sewer gas traveling up through the basin, bypassing the trap seal via the improperly connected vent. Slope arrows indicate the vent pitching toward the fixture connection and the drain pitching toward the stack, with the drain labeled 1/4 inch per foot.

Components

basin faucet basin tailpiece drain trap horizontal branch drain vent pipe vertical stack pipe elbows tee fittings

Defects shown

Vent connected on the fixture side of the trap Vent connection bypassing the trap seal Sewer gas entering through the basin drain