In a return air duct supplying an air handler rated 2000 CFM or greater, which safety device is required?

In a return air duct supplying an air handler rated 2000 CFM or greater, which safety device is required?

• A. Smoke detector
• B. Fire damper
• C. CO detector
• D. Heat sensor

Answer: (A)

In large return air ducts feeding an air handler (2000 CFM or greater), a smoke detector is required to automatically shut down the air handler if smoke is detected. This helps prevent circulating smoke through the building and gives a rapid response to a potential fire, working with the building’s fire alarm system. Fire dampers are used where ducts pass through fire-rated barriers to slow fire spread, not for sensing smoke or controlling the air handler. CO detectors monitor carbon monoxide in spaces, not the duct-based smoke conditions that would necessitate shutting down the equipment. Heat sensors may detect high temperatures but aren’t the standard device mandated for early smoke detection in large return ducts.

In large return air ducts feeding an air handler (2000 CFM or greater), a smoke detector is required to automatically shut down the air handler if smoke is detected. This helps prevent circulating smoke through the building and gives a rapid response to a potential fire, working with the building’s fire alarm system.

Fire dampers are used where ducts pass through fire-rated barriers to slow fire spread, not for sensing smoke or controlling the air handler. CO detectors monitor carbon monoxide in spaces, not the duct-based smoke conditions that would necessitate shutting down the equipment. Heat sensors may detect high temperatures but aren’t the standard device mandated for early smoke detection in large return ducts.