24VDC Smoke/Heat Detector Head. The D283A detector detects the large smoke particles which typically result from wood, paper, and fabric combustion. The D283A is a smoke detector that also has a +135°F (+57°C) fixed temperature heat sensor. Use in areas where the ambient temperature does not exceed +100°F (+38°C). This detector is compatible with 24 VDC circuits. This detector has two components: the detector base and the detector head. The base is permanently attached and wired to a back box. The interchangeable heads quickly detach for replacement and cleaning without affecting circuit wiring.