Duct or discharge air temperature sensor, operating range 40- 250F. C7150 solid-state, mixed-air sensor is used with Honeywell economizer logic modules and W973 and M7415 to proportion outdoor and return air dampers in economizer systems. Uses thermistor sensing element in ventilation duct systems. Negative temperature coefficient (NTC) causes resistance to decrease as sampled air temperature increases. Resistance change used as input to control W973 and M7415. Requires no settings or calibration. Mounts on duct surface with four screws (not supplied).