Bosch D285DH Duct Smoke Detector Head

The D285DH duct detector head is suitable for two-wire or four-wire application, depending on base. The detector is part of a two component system: the duct detector housing and the duct detector head. The housing is permanently attached on the duct. The interchangeable duct detector head quickly detaches for replacement and cleaning without affecting circuit wiring. The D285DH duct detector head attaches to the following duct detector housings: • D340 Two-wire Duct Detector Housing (12 VDC or 24 VDC) • D341 Four-wire Duct Detector Housing (24 VDC or 120 VAC) • D342 Four-wire Duct Detector Housing (24 VDC or 220/240 VAC)