Drainage, Waste & VentQuestion 21 of 120
An air admittance valve is used to vent an island sink. Which statement describes a correct installation?
a.It may be buried in insulation inside a sealed wall cavity
b.It relieves positive pressure in the drainage system
c.It must be accessible and located above the fixture trap weir
d.It replaces the need for any vent open to the atmosphere in the building
Explanation
An air admittance valve must remain accessible for service and be installed above the trap weir of the fixture it serves, in a space with air available to the valve. It admits air only and does not relieve positive pressure, it cannot be sealed off inside insulation, and the building still requires at least one vent open to the atmosphere.
Law Reference: IPC §917Practice all 120 questions free — no signup required.
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