Smoke detectors should not be located in direct airflow or closer than how many inches from an air supply diffuser or return air opening?

Smoke detectors should not be located in direct airflow or closer than how many inches from an air supply diffuser or return air opening?

• A. 60
• B. 24
• C. 48
• D. 36

Answer: (D)

Detectors must be kept out of direct air movement to avoid false alarms and unreliable detection. The standard minimum distance from any air supply diffuser or return opening is 36 inches (3 feet). Placing a detector closer than this can have air currents blow smoke away from the sensing chamber or create drafts that trigger alarms unnecessarily, while staying at or beyond this distance maintains reliable sensing. So the correct rule is not closer than 36 inches.

Detectors must be kept out of direct air movement to avoid false alarms and unreliable detection. The standard minimum distance from any air supply diffuser or return opening is 36 inches (3 feet). Placing a detector closer than this can have air currents blow smoke away from the sensing chamber or create drafts that trigger alarms unnecessarily, while staying at or beyond this distance maintains reliable sensing. So the correct rule is not closer than 36 inches.