Rhode Island Journeyman Plumber Practice Exam

What pressure does a domestic hot water heater operate at maximum?

1. 100 psi

2. 120 psi

3. 150 psi

4. 200 psi

The correct answer is: 150 psi

Domestic hot water heaters typically operate at a maximum pressure of 150 psi. This standard is crucial because it ensures safe operation and prevents potential damage to the system. Operating pressure above this level can lead to equipment failure or safety hazards, such as ruptures or leaks. The pressure rating is established based on the construction and materials used in water heaters. Manufacturers design their products to handle pressures of up to 150 psi, which is a widely accepted safety threshold in residential plumbing systems. The other pressure levels listed, while they may seem reasonable, exceed the commonly accepted design standards for domestic hot water heaters. Therefore, they are not used as maximum operating pressures in conventional residential setups. Understanding these pressure limits is essential for any plumbing professional to ensure the safety and efficiency of water heating systems.