In a high-rise cold water system, what is the purpose of installing pressure-reducing valves (PRVs) and boosters, and when might boosters be needed?

• A. PRVs regulate pressure to maintain suitable zone pressure; boosters may be necessary to raise pressure in distant or upper floors where pressure is low.
• B. PRVs increase pressure; boosters reduce pressure.
• C. PRVs and boosters are decorative.
• D. PRVs are only for hot water systems.

Answer: (A)

In a tall building, you need to both limit and lift pressure to keep the cold-water system reliable. A pressure-reducing valve lowers the incoming pressure to a safe, usable level for the distribution network, protecting pipes, fittings, and fixtures and reducing issues like water hammer. But on distant or upper floors, the water may lose too much pressure as it travels up the riser and through long runs. That’s where boosters come in: they add the needed pressure so fixtures on high floors or far zones still get adequate flow and speed.

So boosters are used when the pressure at the upper or distant parts of the building would otherwise be too low, while PRVs keep the overall system pressure within design limits to protect the install and ensure consistent performance.