Abstract: The invention relates generally to the field of airflow boosting devices. In particular, the invention relates to a booster fan for installation into a vent opening of a duct system in a forced air circulation and delivery system. In an embodiment, the booster fan includes a register plate for covering a vent opening. An opening or openings on the register plate provide an air outlet. A housing is secured to the register plate for enclosing a crossflow fan therein. The crossflow fan is disposed adjacent and spaced from the register plate and resiliently supported at both ends. A motor is resiliently connected to the crossflow fan. The housing also has an aperture for providing an air inlet communicating with the duct system. Preferably, two arcuate air deflection panels are provided in the housing for connecting the air inlet and air outlet to form a guided air passageway.