North Carolina Home Inspector Practice Exam

At what pressure and temperature does a temperature and pressure relief valve on a hot water heater typically open?

1. 100 psi and 180 deg. Fahrenheit

2. 150 psi and 210 deg. Fahrenheit

3. 200 psi and 220 deg. Fahrenheit

4. 120 psi and 190 deg. Fahrenheit

The correct answer is: 150 psi and 210 deg. Fahrenheit

The typical pressure and temperature at which a temperature and pressure relief valve on a hot water heater opens is set to prevent potential excess pressure and overheating, which could lead to dangerous situations. The standard setting for most residential hot water heaters is, indeed, at 150 psi and 210 degrees Fahrenheit. These parameters are designed to ensure safety by allowing the valve to release water when the pressure or temperature exceeds these limits, thus avoiding potential damage to the tank or a hazardous failure. In residential applications, these values are compliant with safety standards and are guided by the manufacturer's specifications. The choice of 150 psi is a common threshold that can handle the pressures typically generated in a hot water system, while 210 degrees Fahrenheit is a critical temperature limit above which the risk of steam generation increases significantly. Understanding these settings is crucial for maintaining safety in plumbing systems and for the proper functioning of water heaters. Regular inspection and functioning checks of the T&P relief valve are essential to ensure that it operates under these specified conditions.