A boiler with over 500 ft² of heating surface requires two what?

• A. PSVs
• B. Feedwater Pumps
• C. Draft Regulators
• D. Combustion Analyzers

Answer: (A)

On a boiler of this size, safety against overpressure is addressed with redundancy in the relief system. When the heating surface exceeds 500 ft², the standard practice is to install two pressure relief valves. This ensures that if one valve fails to open, leaks, or becomes obstructed, the other valve can still relieve pressure and prevent a dangerous buildup. The two valves are sized so their combined relief capacity meets the boiler’s maximum possible relief needs, and they’re typically set to the same pressure to ensure consistent protection.

The other items serve different functions and aren’t tied to this specific sizing rule: feedwater pumps supply water to the boiler, but aren’t about relieving excess pressure; draft regulators control burner air supply during operation; combustion analyzers monitor combustion efficiency and emissions rather than safety relief capacity.