CSLB Class B General Contractor's License Practice Exam

Which of the following actions might NOT reduce the pressure in a plumbing system?

1. Installing a pressure reducing valve

2. Opening more faucets concurrently

3. Using a hose to direct pressure outward

4. Closing all valves in the system

The correct answer is: Closing all valves in the system

Closing all valves in the plumbing system will prevent water from flowing through any of the pipes, which can lead to a buildup of pressure, especially if water is still being supplied to the system. This action essentially isolates the water supply and can create an increase in pressure in the closed system rather than reducing it. In contrast, installing a pressure reducing valve is specifically designed to lower water pressure to a safe and manageable level. Opening more faucets concurrently can help lower pressure because it allows water to flow out, effectively reducing the pressure within the system as more outlets are available for the water. Using a hose to direct pressure outward can similarly help dissipate pressure by providing an outlet for the water to escape. Thus, closing all valves does not create an outlet for pressure relief, making it the option that will not reduce the water pressure in the plumbing system.