Life Safety Essentials: Smoke Detector Near HVAC Diffuser

Learning Objective: To identify if a smoke detector is too close to an HVAC diffuser.

By Robert Trotter, CBO, CFM, MCP - Manager, Sr. Life Safety Specialist
  

Smoke detectors are an integral component of a fire alarm and detection system. Placement of detectors and other devices are essential to proper operation of the system. Smoke detectors installed too close to HVAC diffusers may cause nuisance alarms, and more importantly fail to function or cause a delay in alarm transmission and occupant notification. Most people believe detectors are required to be installed at least 3 ft from an HVAC diffuser. Smoke detectors are to be installed out of the air stream. To correct the deficiency detectors can be relocated or the diffuser can be changed to distribute a different air stream.

The occupancy chapters of NFPA 101®, Life Safety Code®, 2000 Edition, requires fire alarm systems to comply with the provisions of 9.6. A fire alarm system required for life safety must be installed, tested, and maintained in accordance with the applicable requirements of NFPA 70, National Electrical Code [1999 edition]. Section 2-3.5.1* states “In spaces served by air-handling systems, detectors shall not be located where airflow prevents operation of the detectors”. The Appendix states Detectors should not be located in a direct airflow nor closer than 3 ft (1 m) from an air supply diffuser or return air opening. Supply or return sources larger than those commonly found in residential and small commercial establishments can require greater clearance to smoke detectors. Similarly, smoke detectors should be located farther away from high velocity air supplies.

  

When using The Joint Commission’s 2011 Hospital Accreditation Standards to identify this type of deficiency apply LS.02.01.34 Element of Performance 4 since the hospital would not be meeting this provision of the Life Safety Code® for fire alarms.