Though smoke detectors and heat detectors perform different functions, both can save lives during a fire. Smoke detectors are a more common fixture in homes, but heat detectors have several advantages. Used together, both types of detectors provide extra warning for inhabitants of burning buildings.
Smoke detectors incorporate two types of technology -- ionization and photoelectric -- both of which often are combined for optimum protection. In ionization smoke detectors, a chamber contains two plates that generate an electric current. If smoke interrupts that current, an alarm sounds. Photoelectric smoke detectors incorporate a light beam that shines into a receptor inside the devices. If smoke interrupts the beam in any way, the alarm sounds.
Ionizations detectors tend to respond more rapidly in cases of high flames, while photoelectric detectors react best to long, smoldering fires. Because of these strengths and weaknesses, some smoke alarms contain both photoelectric and ionization technology. While research shows either type of smoke alarm provides potentially life-saving warnings, the National Fire Protection Association recommends combining both types of detectors in the home.
Because many fires begin with billowing smoke before intense heat builds up, smoke detectors can sound the alarm before heat detectors activate.
Heat detectors use two main types of technology: thermocouple and electro-pneumatic. Both detect changes in temperature in the area surrounding the alarms. Like smoke detectors, heat detectors include battery-operated and hard-wired electrical varieties or combine both technologies. One type relies on a mechanical triggering apparatus without requiring batteries or electricity.
Heat detectors function best in fires that involve high flames, intense heat and little initial smoke. Heat detectors also provide a more reliable fire detection device in dusty or dirty environments in which false alarms can be triggered on smoke detectors.
Heat detectors, however, fall short in fires involving heavy smoke but little initial heat.
Install heat detectors in areas posing a higher likelihood of high flames and intense heat, such as in chemical or fuel storage rooms. Heat detectors also should be installed in high-ceiling areas where smoke may not trigger smoke alarms.
Smoke detectors work best in areas in which smokey fires would occur, such as near wood and paper storage.
FireSafety.gov recommends placing smoke detectors on every level of a dwelling or building, in hallways and corridors outside of all sleeping areas and in all bedrooms. Install the devices in the center of ceilings or on walls 6 to 12 inches below the ceiling for best results.