Things You'll Need
Chair or ladder
Duct tape (optional)
Ceiling air diffusers are the vents that attach to the exterior of air ducts and have metal fins that point in multiple directions. As air exits the ducts, the fins diffuse it into different areas of the room. If you have a damaged or rusted diffuser, you can replace it with a new one using nothing more than a screwdriver. Although diffusers come in round, square and rectangle shapes, they all attach in the same method using screws.
Climb up onto a chair or a ladder so that you can easily access the ceiling air diffuser. For safety purposes, the ladder or chair must be tall enough so that both of your hands can lay flat on the ceiling.
Note the shape of the diffuser and then measure the length and the width using a tape measure. If the diffuser is round, simply measure the diameter, which is the distance from one side to the other through the center. Take the measurements with you to purchase a replacement diffuser at a hardware store.
Look at the center of the diffuser to see if there is a post that hangs down from the center. If so, grasp it with your hand and turn it counterclockwise until it detaches. Then pull it down from the ceiling. If no post exists, skip this step.
Look at the perimeter or center of the diffuser and locate the three to four screws that hold it to the ceiling. Remove each screw by turning them counterclockwise with a screwdriver.
Grasp the diffuser and pull it down from the ceiling gently. Set the old diffuser aside and pick up the replacement diffuser.
Push the top of the new diffuser into the ceiling until it is flush. Insert the new screws into the screw holes to secure it to the ceiling or the upper vent assembly, depending on the model.
Insert the center post, if applicable, by turning it clockwise until it is secure.
Some diffuser models attach directly to the flexible air duct in the ceiling. Connect these by pulling the duct over the round top opening on the diffuser and secure it with duct tape. Then push the diffuser up and secure it to the ceiling with screws.