Where are duct smoke detectors typically installed and what hazard do they protect?

• A. In HVAC ducts to detect smoke before it reaches occupied spaces.
• B. In living spaces to monitor smoke levels for comfort.
• C. On the roof to detect cloud formation.
• D. In the basement to detect moisture.

Answer: (A)

Duct smoke detectors are placed in the HVAC ductwork so smoke is detected as it travels through the system, before it reaches occupied spaces. This early detection is crucial because it allows the fire alarm system to respond and HVAC equipment to be controlled—such as shutting down supply fans or closing dampers—to prevent smoke from circulating through the building. By catching smoke in the ducts, these detectors help keep common areas safer, buy time for occupants to evacuate, and reduce the spread of smoke and toxic gases.

Other locations like living spaces, rooftops, or basements are not where duct detectors are typically installed, and detecting moisture isn’t the primary function of a duct smoke detector.