NHIE Plumbing 3 — Questions and Answers
Question 1: What is the maximum temperature a residential water heater should be set to in order to prevent scalding?
- 100°F
- 110°F
- 120°F (Correct answer)
- 140°F
Correct answer: 120°F
The recommended maximum water heater temperature is 120°F to prevent scalding while still being hot enough to inhibit Legionella bacteria growth.
Question 2: A home inspector identifies copper supply pipes with a greenish-white crust on the outside of soldered joints. What does this indicate?
- Normal aging of copper pipe requiring no action
- Active or past pinhole leaks or weeping at the solder joint (Correct answer)
- The pipe has been exposed to excessive water pressure
- Evidence of electrolytic corrosion from dissimilar metals only
Correct answer: Active or past pinhole leaks or weeping at the solder joint
Greenish-white mineral deposits (verdigris) on copper pipe joints indicate moisture has escaped, signaling a pinhole leak or failing solder joint.
Question 3: Which material requires a dielectric union when connected directly to copper pipe?
- PEX tubing
- CPVC pipe
- Galvanized steel pipe (Correct answer)
- PVC pipe
Correct answer: Galvanized steel pipe
Galvanized steel connected directly to copper creates a galvanic cell that accelerates corrosion; a dielectric union electrically isolates the two metals.
Question 4: What is the function of a pressure-reducing valve (PRV) installed on the main water supply?
- It boosts pressure for homes on low-pressure municipal systems
- It reduces incoming municipal water pressure to a safe range for household plumbing (Correct answer)
- It filters sediment from the incoming water supply
- It prevents backflow into the municipal supply
Correct answer: It reduces incoming municipal water pressure to a safe range for household plumbing
A PRV reduces high incoming municipal water pressure (often 80-150 psi) to a safe household range of 40-80 psi to protect fixtures and pipes.
Question 5: An inspector notes that a floor drain in a basement utility room has no visible water in the trap. What is the recommended correction?
- Cap the drain permanently
- Pour water into the drain to replenish the trap seal and prevent sewer gas entry (Correct answer)
- Install a new P-trap
- Add a vent pipe to the drain
Correct answer: Pour water into the drain to replenish the trap seal and prevent sewer gas entry
Infrequently used floor drains can lose their trap water seal through evaporation; pouring water into the drain restores the seal that blocks sewer gases.
Question 6: What type of pipe fitting is used to change direction 90 degrees on a DWV drain line while minimizing flow restriction?
- Standard 90-degree elbow (ell)
- Long-sweep 90-degree elbow (Correct answer)
- Sanitary tee
- Street elbow
Correct answer: Long-sweep 90-degree elbow
A long-sweep 90-degree elbow has a gradual curve that minimizes turbulence and resistance in drain flow, making it the preferred fitting for horizontal DWV runs.
Question 7: Which condition indicates a sump pump system requires attention during a home inspection?
- The sump pump discharges to the yard at least 6 feet from the foundation
- The discharge pipe terminates near the window well of the basement (Correct answer)
- The sump pit has a sealed lid with a vent
- The pump activates when water is poured into the pit
Correct answer: The discharge pipe terminates near the window well of the basement
Discharging sump water near a window well or back toward the foundation defeats the purpose and can reintroduce water into the basement.
NHIE Plumbing 3
What is the maximum temperature a residential water heater should be set to in order to prevent scalding?