What distance must a smoke detector be installed from an air supply or return vent?

When determining the appropriate installation distance for a smoke detector from an air supply or return vent, the requirement is typically set at a minimum of 3 feet. This guideline exists to prevent any interference that might be caused by the airflow from the vent, which could potentially affect the smoke detector's ability to accurately sense smoke or other particulates in the air.

If a smoke detector is installed too close to a vent, it might be exposed to excessive airflow, which can dilute smoke before it reaches the detector, resulting in a delayed or inadequate response to a fire. Maintaining a distance of at least 3 feet ensures that the smoke detector can operate effectively and provide timely alerts, thus enhancing safety measures in residential or commercial spaces.

The other distances provided in the options—1 foot, 2 feet, and 5 feet—do not meet the standard requirements for optimal installation relative to air vents, making them less favorable choices in terms of the smoke detector's performance and reliability.