A primer on selection, installation and testing. Which type of duct smoke detector is preferred for HVAC applications, photoelectric or ionization?
Photoelectric detection is preferred for several reasons, including: 1. Detection Capability — Photoelectric detection responds better to the larger smoke particles found in ductwork during a fire. 2. NFPA Recommends Photoelectric — The National Fire Alarm Code Standard 72, section A.5.14.4.2 explicitly states, “In almost every fire scenario in an air-handling system, the point of detection will be some distance from the fire source, therefore, the smoke will be cooler and more visible because of the growth of sub-micron particles into larger particles due to agglomeration and recombination. For these reasons, photoelectric detection technology has advantages over ionization detection technology in air duct system applications.” 3. Environmental Immunity — High humidity and condensation can cause false alarms with ionization detectors. Photoelectric detectors operate more efficiently, generating fewer false alarms. 4. Industry Preferred — Photoelectric detection is preferred by the fir
