Home Inspector Plumbing DWV Systems Flashcards
7 cards from real Home Inspector Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Home Inspector Plumbing DWV Systems flashcards as text
Which type of vent connects a fixture drain to the main vent stack without requiring its own separate vent pipe penetrating the roof?
Answer: Wet vent
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.
During inspection, a home inspector notes that a vent pipe terminates 6 inches above the roof surface. What is the concern?
Answer: The pipe may be covered by snow or debris, blocking the vent
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.
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?
Answer: Wastewater can back-siphon into the dishwasher
Without a high loop or air gap, contaminated drain water can back-flow into the dishwasher, creating a cross-connection health hazard.
What is the maximum distance allowed between a fixture trap and its vent connection for a 1.5-inch drain pipe?
Answer: 3.5 feet
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.
Which of the following best describes an 'air admittance valve' (AAV) in a DWV system?
Answer: A one-way valve that allows air in but not sewer gas out
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.
A home inspector observes a 4-inch cast iron soil stack that has significant horizontal crackling and scaling on its exterior. What is the recommended action?
Answer: Note it as a material deficiency and recommend evaluation by a licensed plumber
Exterior scaling and cracking of cast iron indicates corrosion and potential structural failure; a licensed plumber should evaluate for replacement.
Which fitting type is required when making a direction change from vertical to horizontal in a drain line?
Answer: Long-sweep 90-degree or two 45-degree fittings
Long-sweep 90s or two 45-degree fittings are required for vertical-to-horizontal transitions to maintain flow velocity and reduce clogging risk.