BOC Plumbing and Water Systems Flashcards

What is the primary purpose of a backflow preventer in a building's plumbing system?

Answer: To prevent contaminated water from flowing back into the potable water supply

Backflow preventers stop contaminated or non-potable water from reversing flow and entering the clean drinking water supply due to back-pressure or back-siphonage.

Which type of water heater is typically most energy-efficient for commercial buildings with high and consistent hot water demand?

Answer: Condensing boiler-based indirect water heater

Condensing boiler-based indirect systems achieve very high efficiency by capturing flue gas heat and are well-suited for large, consistent commercial hot water loads.

What does a pressure-reducing valve (PRV) do in a building water system?

Answer: Steps down high street main pressure to a safe working pressure inside the building

A PRV reduces and stabilizes high incoming municipal water pressure to a safe level, typically 60–80 psi, to protect fixtures and piping from damage.

Which test is used to check a sanitary drain system for leaks before walls are closed during construction or renovation?

Answer: Hydrostatic pressure test

A hydrostatic (water) pressure test fills the drain system with water to check for leaks by monitoring water level loss over time.

In a building's domestic hot water system, what is the purpose of a recirculation loop?

Answer: To ensure hot water is quickly available at fixtures without long wait times

A recirculation loop continuously circulates hot water through the distribution piping so occupants get near-instant hot water at any fixture.

What type of valve should be installed as the main water shut-off for a building to allow full flow with minimal pressure loss?

Answer: Gate valve or full-port ball valve

Gate valves and full-port ball valves are designed for fully open or fully closed service with minimal pressure drop, making them ideal as main isolation valves.