The F1000-450 Discovery Heat Detector is an anaolg addressable device that has a common profile with the F1000-550 Discovery Ionization and F1000-650 Discovery Photoelectric Smoke Detectors but has a low air flow resistance case made of self-extinguishing white polycarbonate. The Heat Detector uses a single thermistor to sense the air temperature at the detector position. The thermistor is connected in a resistor network which provides a voltage output proportional to the external air temperature.