Bosch D273THCS Smoke and Heat Detector - Relay&Sounder 137-degreeF

D273THCS Four-Wire Smoke/Heat Detector with Auxiliary Relay and Sounder. Four-wire smoke detector with a 135°F (57°C) heat sensor, an auxiliary relay, and a sounder. This detector model is UL Listed and works with commercial fire protective signaling and household fire warning systems. Detects smoke particles produced during wood, paper, and fabric combustion. Sounders produce 85 dB at 10 ft (3 m). This detector model use an infrared (IR) LED light source and a silicon photodiode to measure light in a chamber. A fine screen covers the chamber to deter insects and reduce dust accumulation and nuisance alarms. During a fire, smoke particles reflect light onto the photodiode. When the photodiode measurements exceed the alarm threshold, the detector signals an alarm condition. After the alarm