Plumbing Water Supply Systems 1 — Questions and Answers
Question 1: What is the minimum water pressure required at a residential fixture per the IPC?
- 15 psi
- 20 psi (Correct answer)
- 40 psi
- 60 psi
Correct answer: 20 psi
The IPC requires a minimum static water pressure of 20 psi at every plumbing fixture to ensure adequate flow for proper operation.
Question 2: What is the maximum water pressure allowed at a residential service entrance without a pressure reducing valve (PRV)?
- 60 psi
- 80 psi (Correct answer)
- 100 psi
- 125 psi
Correct answer: 80 psi
Water pressure exceeding 80 psi at the service entrance requires a pressure reducing valve (PRV) to protect the plumbing system and appliances.
Question 3: What device is required to prevent backflow where a hose bib connects to a garden hose?
- Pressure reducing valve
- Vacuum breaker (Correct answer)
- Check valve
- Gate valve
Correct answer: Vacuum breaker
A vacuum breaker (anti-siphon device) is required at hose bibbs to prevent contaminated water from being siphoned back into the potable water supply.
Question 4: What is the purpose of a pressure reducing valve (PRV) in a residential plumbing system?
- To boost low water pressure
- To reduce high incoming water pressure to a safe level (Correct answer)
- To prevent water hammer
- To filter sediment from water
Correct answer: To reduce high incoming water pressure to a safe level
A PRV reduces high municipal water pressure to a safe operating pressure (typically 50-60 psi) to protect fixtures, appliances, and pipes.
Question 5: Which type of water heater heats water only when it is needed, without a storage tank?
- Heat pump water heater
- Solar water heater
- Tankless (on-demand) water heater (Correct answer)
- Storage tank water heater
Correct answer: Tankless (on-demand) water heater
A tankless (on-demand) water heater heats water directly as it flows through the unit, eliminating standby heat loss associated with storage tanks.
Question 6: What is 'water hammer' and what device prevents it?
- Corrosion in pipes; prevented by a filter
- Pressure spike from sudden valve closure; prevented by a water hammer arrestor (Correct answer)
- Frozen pipe noise; prevented by insulation
- Air in supply lines; prevented by a pressure regulator
Correct answer: Pressure spike from sudden valve closure; prevented by a water hammer arrestor
Water hammer is a pressure surge or shock wave caused by sudden valve closure, and a water hammer arrestor absorbs the shockwave to protect pipes and fittings.
Plumbing Water Supply Systems 1
What is the minimum water pressure required at a residential fixture per the IPC?