Abstract: An indoor cassette unit for a variable refrigerant flow system. The cassette unit has a cabinet structure with a main housing. A heat exchanger, such as a refrigerant coil, and a motorized fan are retained by the cabinet structure. A primary air inlet is disposed in fluidic communication with an inner volume of the main housing, and a tapered duct section is interposed between the heat exchanger and the fan to establish a sub-volume within the main housing and a physically spaced distance between the heat exchanger and the fan. An inlet volume sensor and a volume control device can cooperate to act as an air inlet valve. A secondary housing with an inner volume can be fixed to the main housing. A filter rack is retained in juxtaposition with the heat exchanger. A return air inlet can be disposed in fluidic communication with the inner volume.