What is the minimum allowable horizontal distance for smoke detectors placed near HVAC vents?

The minimum allowable horizontal distance for smoke detectors placed near HVAC vents is three feet. This requirement is in place to prevent the airflow from the vents from adversely affecting the detector's ability to sense smoke. When smoke detectors are located too close to HVAC vents, the airflow can either push smoke away from the detector, delaying its activation, or may cause false alarms. This distance helps ensure that the smoke detector operates effectively, allowing it to detect smoke particles efficiently without interference from the heating, ventilation, or air conditioning system. Proper placement is critical to maintaining safety and enhancing the reliability of fire alarm systems.