What is a common setting for a high-limit aquastat?

• A. 120 °F (49 °C).
• B. 180 °F (82 °C).
• C. 140 °F (60 °C).
• D. 200 °F (93 °C).

Answer: (B)

A high-limit aquastat acts as a safety control that shuts the burner off when boiler water reaches a preset high temperature, preventing overheating and potential damage to the boiler and piping. Around 180 °F (82 °C) is a common setting because it provides enough heat for typical heating needs while staying below temperatures that could cause excessive pressure or stress on the system. Lower options like 120 °F are generally for domestic hot water delivery rather than a safety limit for the boiler, while 140 °F is less common as the standard high limit, and 200 °F is typically too high for standard boiler designs.