Bosch Security D273TH


Four-Wire Smoke/Heat Sensor
Four-wire smoke detector with a 135°F (57°C) heat sensor.

Availability: Please Call for Availability

  • Factory New
  • Material Obsolete
Brand: Bosch Security Part #: 50230 Categories: , Manufacturer Part #: D273TH


The D273 Family includes the following detector models:

Model Description
D273 Four-wire
D273IS¹ Four-wire with an isolated 135°F (57°C) heat sensor and sounder
D273TH Four-wire with 135°F (57°C) heat sensor
D273THC Four-wire with 135°F (57°C) heat sensor and auxiliary relay
D273THCS¹ Four-wire with 135°F (57°C) heat sensor, auxiliary relay, and sounder
D273THE Four-wire with 135°F (57°C) heat sensor and EOL relay
D273THR² Four-wire with 135°F (57°C) heat sensor and trouble relay
D273THS¹ Four-wire with 135°F (57°C) heat sensor and sounder
D273THES¹ Four-wire with 135°F (57°C) heat sensor, sounder, and EOL relay

¹   Sounders produce 85 dB at 10 ft (3 m)
²   The trouble relay indicates both Dirty Smoke Chamber and/or Power Loss conditions

Each of the detector models is UL Listed and works with commercial fire protective signaling and household fire warning systems. Each model detects smoke particles produced during wood, paper, and fabric combustion.


Weight 0.2 lbs


Material Qualities

Fire Retardant, High Impact Resistance

Detection Method

Fixed Temperature, Photoelectric

Thermal Rating






Bosch Security

Production Status



  • 12 VDC or 24VDC input
  • Designed for commercial or residential use
  • Four-wire application
  • Light-emitting diodes (LEDs) indicate the status of the chamber, power, and alarm
  • Removable terminal block to simplify wiring connections


D273 Photoelectric Smoke and Heat Detectors
Bosch Security – Data Sheet – 2014
Photoelectric Smoke Detector; D263 / D273 Series
Bosch Security – Installation Instructions – 2006
Smoke Detectors
Bosch Security – Technical Service Note – 2000

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