The pressure relief valve on a water heater must open at or not exceed what pressure?

• A. 150 PSI
• B. 100 PSI
• C. 200 PSI
• D. 75 PSI

Answer: (A)

The device’s job is to keep the water heater from overpressurizing. It should begin to open when the pressure reaches about 150 psi, so it vents water and lowers the tank pressure before a dangerous level can develop. Normal home water pressures are well below this threshold, so the valve stays shut during regular operation and only relieves pressure when something pushes the system higher than safe.

Choosing 150 psi as the opening point balances safety and practicality. Opening too low, like 75 or 100 psi, would cause nuisance venting and leaks during normal pressure fluctuations. Opening too high, like 200 psi, could allow the tank to reach unsafe pressures before relief occurs.