Home Inspector Test Home Inspector Plumbing DWV Systems 3

Question 1

Which type of vent connects a fixture drain to the main vent stack without requiring its own separate vent pipe penetrating the roof?

Accepted Answer

Wet vent

Answer

A wet vent serves as both a drain and a vent for one fixture while providing venting for another, reducing the number of roof penetrations needed.

Question 2

During inspection, a home inspector notes that a vent pipe terminates 6 inches above the roof surface. What is the concern?

Accepted Answer

The pipe may be covered by snow or debris, blocking the vent

Answer

Most codes require vent pipes to extend at least 6 inches above the roof, but in snow country a minimum of 12 inches is often required to prevent blockage.

Question 3

A home inspector finds that a kitchen sink drain connects to the dishwasher drain without a high loop or air gap. What is the deficiency?

Accepted Answer

Wastewater can back-siphon into the dishwasher

Answer

Without a high loop or air gap, contaminated drain water can back-flow into the dishwasher, creating a cross-connection health hazard.

Question 4

What is the maximum distance allowed between a fixture trap and its vent connection for a 1.5-inch drain pipe?

Accepted Answer

3.5 feet

Answer

For a 1.5-inch pipe, the trap-to-vent distance (trap arm length) is limited to 3.5 feet to prevent siphoning of the trap seal.

Question 5

Which of the following best describes an 'air admittance valve' (AAV) in a DWV system?

Accepted Answer

A one-way valve that allows air in but not sewer gas out

Answer

An AAV is a spring-loaded, one-way mechanical vent that opens to admit air when negative pressure develops in the drain, eliminating the need for a traditional vent pipe.

Home Inspector Test Practice Test

Home Inspector Test Practice Test

Home Inspector Test Home Inspector Plumbing DWV Systems 3