Bosch D273THES 4-Wire Smoke/Heat Detector with EOL Relay and Sounder None

D273THES Four-Wire Smoke/Heat Detector with EOL Relay and Sounder. Four-wire smoke detector with a 135°F (57°C) heat sensor, a sounder, and an EOL relay. The detector model is UL listed and works with commercial fire protective signaling and household fire warning systems. The model detects smoke particles produced during wood, paper, and fabric combustion. This detector uses 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 condition clears, interrupt power at the