ACI Series Sensors are designed specifically for HVAC system temperature control. The averaging sensors come in thermistor and RTD sensor curves compatible with most BAS systems available today. Averaging sensors come with a foambacked handy box and in 12' (3.7m) or 24' (7.3) lengths. The ACI/*A Averaging Duct Sensor should be mounted across a duct in a serpentine fashion with bends in a smooth ark using an M-648 clip. The RTD probe is sensitive for the entire length, while the thermistor is sensitive at nine evenly spaced sensor locations. Use standard metal screws to secure to the duct.