Plumbing Water Supply Systems 2 — Questions and Answers
Question 1: What is the purpose of a tempering valve (mixing valve) on a water heater?
- To increase water pressure
- To blend hot and cold water to deliver water at a safe temperature (Correct answer)
- To prevent sediment buildup
- To measure water flow rate
Correct answer: To blend hot and cold water to deliver water at a safe temperature
A tempering valve blends hot and cold water to deliver water at a pre-set safe temperature (typically 120°F) to prevent scalding.
Question 2: What is cross-connection in a plumbing system?
- Two pipes crossing each other in a wall
- A physical link between potable water and a non-potable source (Correct answer)
- The connection point of supply and drain lines
- A fitting joining two different pipe sizes
Correct answer: A physical link between potable water and a non-potable source
A cross-connection is any physical connection between potable (drinking) water and a non-potable source that could allow contamination of the drinking water supply.
Question 3: What is the recommended setting for a residential water heater thermostat to balance energy efficiency and safety?
- 100°F
- 120°F (Correct answer)
- 140°F
- 160°F
Correct answer: 120°F
120°F (49°C) is the EPA-recommended setting that balances energy efficiency, Legionella prevention, and scald protection for most households.
Question 4: What is the function of the anode rod in a tank-type water heater?
- To heat the water
- To sacrifice itself to corrosion, protecting the tank lining (Correct answer)
- To filter sediment
- To regulate water pressure
Correct answer: To sacrifice itself to corrosion, protecting the tank lining
The anode rod (sacrificial anode) is made of magnesium or aluminum and corrodes preferentially to protect the steel tank lining from rust.
Question 5: What does a pressure and temperature (P&T) relief valve on a water heater do?
- Regulates incoming water pressure
- Automatically releases water if pressure or temperature exceeds safe limits (Correct answer)
- Controls the thermostat setting
- Prevents cold water from entering the tank
Correct answer: Automatically releases water if pressure or temperature exceeds safe limits
The P&T relief valve is a critical safety device that automatically opens to release water and pressure if the tank exceeds safe temperature (210°F) or pressure (150 psi) limits.
Question 6: What is the purpose of a check valve in a water supply system?
- To reduce water pressure
- To allow water flow in only one direction (Correct answer)
- To filter debris from water
- To measure water consumption
Correct answer: To allow water flow in only one direction
A check valve allows water to flow in only one direction, preventing backflow that could contaminate the supply system or damage equipment.
Plumbing Water Supply Systems 2
What is the purpose of a tempering valve (mixing valve) on a water heater?