Illinois Plumbing Code Practice

At what maximum pressure should a pressure relief valve open in relation to the rating of a water heater?

1. 100 psi

2. 125 psi

3. 150 psi

4. 175 psi

The correct answer is: 150 psi

The correct choice is based on the standard requirements for pressure relief valves in water heaters. A pressure relief valve is a safety device designed to open and relieve pressure when it exceeds a certain threshold, thus preventing dangerous over-pressurization of the water heater. Typically, a pressure relief valve should open at a pressure not exceeding 150 psi. This rating aligns with common industry standards and sewer regulations, ensuring that water heaters can safely handle the pressure while providing adequate protection against potential hazards. Valves set to open at lower pressures, such as 100 or 125 psi, may lead to unnecessary activation and could create other issues like system inefficiency. Similarly, 175 psi exceeds the operational limits set for most residential water heaters, which could lead to dangerous conditions as it surpasses the manufacturer’s safety guidelines. Thus, a setting of 150 psi is ideal for balancing safety and functionality in plumbing systems.