Kitchen exhaust fans are installed directly over the hob, usually inside the stove's range hood. Exhaust fans pull indoor air out of the kitchen and draw in fresher outdoor air. They are used to decrease both strong cooking smells and the amount of moisture in the cooking area.
To begin installing a kitchen exhaust fan, turn off the power. Then, use a 3/8-spade bit to drill a hole through the ceiling into the attic in the location you would like to place the fan. In the attic, clear insulation from the area where you will create the vent hole, using the ceiling cutout you made earlier as a reference for the hole size.
Measure the vent fan's intake port (the part that will be installed into the ceiling), and make a reference hole this size. Use this reference drill hole to draw the exact size of hole you will need to cut into the ceiling. Use a drywall saw, jigsaw or reciprocating saw to cut out this portion of the ceiling.
In the attic, attach a duct elbow (usually a 90-degree, 4-inch elbow works fine) to the exhaust fan's outlet port, using duct tape to tape it securely in place. Be sure to use foil duct tape to protect against deterioration in the future.
Attach a cable connector to the fan's housing side, insert the metal brackets that came with the fan into the sides, and put the vent fan into the ceiling hole. Make sure the metal brackets extend to contact the closest joists, then screw them into place. Put the electrical cable through the cable connector. Using a wall cap kit, tape a flexible duct to the elbow that you previously attached to the vent fan.
You'll now need to make a duct hole for the exhaust fan to vent air outside of the house. Find a location on the attic wall that is close to the fan and between wall studs. On the outside of the house, identify where this location is, and cut a hole in the wall using a hole saw.
Back in the attic, use foil duct tape to connect a foot-long connector duct to the wall cap, then slide the cap into the hole in the wall. Secure with a rubber gasket and silicone adhesive, and screw it to the house's siding. Attach the duct end of the flexible exhaust duct to the connector duct of the wall cap with foil duct tape.
Inside the kitchen, make the appropriate wire connections and attach the fan's grille. Turn the power back on and test the fan.