Similarly, make sure the hood will hang 24 to 30 inches above the stove, and will cover the entire cooking space. Ideally, there should be a three inch overhang between the edge of the hood and the edge of the cooking space. [2] X Research source
Have someone hold the hood up while you unscrew it so it doesn’t fall down. [4] X Research source This is a good opportunity to use a voltage adapter to make certain the power to this area of your home is off before you proceed any further. [5] X Research source
If the fan and filters are attached, remove them to expose the wiring. [6] X Research source There may also be a panel over the electrical wiring that needs to be removed.
Work carefully so as not to damage the metal of the hood as you remove the knockouts. The wiring knockout should create a small, round hole in the hood.
One way to do this is to lift the hood up to where you will install it and have someone else create an outline by tracing inside the holes with a pencil. [8] X Research source Alternatively, you can measure the holes, then measure the space, find the center point of the wall, and align your holes accordingly. [9] X Research source This method works well if you don’t have a helper to trace the holes for you. The instructions that came with your hood should provide further guidelines on creating outlines for the holes via this method. [10] X Research source Make certain to plan for both duct and wiring holes. If the duct and wiring holes in your new hood match up exactly with the old one, you may not need to mark or cut your wall. In this case, you can skip parts 2 and 3 altogether and work with the existing holes and ducting.
These holes in the outside wall should line up exactly with the ones inside, allowing you to install a duct cap outside that will line up perfectly with your interior ductwork. If your stove is positioned against an interior wall, you will need to install additional ducting to create a vent to the outside. The duct can go up through the cabinets and between ceiling joists, and then out through the nearest exterior wall. [12] X Research source However you position your duct, make certain it ultimately leads outdoors. Never create a ventilation duct that ends in your attic or anywhere else inside your home. This can create serious mold problems. [13] X Research source
Drilling a hole in the outline for the electrical wiring will make it easier to cut out.
Use a reciprocating saw, saber saw, or keyhole saw to cut all the way through, from the exterior to the interior. Remove any loose insulation or other debris that might get in the way of your duct. [16] X Research source
If it is not long enough, you’ll need to purchase a duct extension, which can be attached to the cap with sheet metal screws and duct tape. [17] X Research source By the same token, if the duct is too long, trim the excess ductwork using metal shears.
Push the hood upward to allow it to connect with the ductwork.
Cover the exposed ends with a wire nut. If there is not enough exposed wire, strip the sheathing off the ends with a pair of wire strippers.
Damp or greasy air that is not pulled through the duct may cause damage to your walls.
