Turn off the power to the Broan fan in your circuit breaker panel.
Remove the ceiling grille for your old Broan bath fan. Pull straight down on it and squeeze together the retaining spring to remove.
Climb into the attic. Unscrew the ducting from the fan and pull off. Open the electrical box and disconnect the wiring by unscrewing the wire nuts and pulling the wires apart. Pull the wiring out of the electrical box.
Unscrew the Broan fan from the ceiling joists and pull it out of the ceiling opening.
Position the new Broan fan into the ceiling opening. Screw the housing to the ceiling joists.
Slide the electrical wiring into the electrical box. Connect the black wires together with a wire nut, the white wires together with a wire nut and the green wires together with a wire nut. Screw the cover on to the electrical box.
Snap the duct connector on to the housing. The top of the duct connector needs to be flush with the top of the housing.
Slide the ductwork on to the duct connector. Tape the ductwork on to the duct connector with foil tape. Inserting a screw in the wrong location will cause the damper to fail to open.
Connect the new grille from below. Squeeze the springs together and insert them into the slots on the housing. Push up on the grille to snap it into place.
Restore the power to the circuit and test out the new exhaust fan.