Both detectors have advanced solid-state, low-voltage, surface-mount circuitry and are designed for 2-wire and 4-wire installation using the appropriate detector base. The detectors are designed for Open Area Protection (UL 521) and may be installed in systems intended for Releasing Device Service through use of a compatible fire alarm control panel.
The THD-7052 and THD-7053 are thermistor-based electronic heat detectors with a 135°F (57°C) fixed temperature set point. In addition, the THD-7052 model has a Rate-Of-Rise of temperature detection feature rated at 15°F (8.3°C) per minute. Two Red Light Emitting Diodes are located diametrically opposite each other to allow 360-degree viewing. Both LEDs continuously indicate the operating condition of the Detector. During standby, the LEDs flash once every six seconds. During alarm, both LEDs light steady at full brilliance. A double flash every six seconds indicates a detector with a thermistor trouble. An optional base is available to provide remote LED function. A unique gated output circuit design provides improved stability and transient suppression. Special signal processing techniques verify the presence of smoke before the detector will alarm.