Range hoods are necessity in any kitchen. a properly installed range hood will vent hot air and cooking odours outside as well as help keep the kitchen surfaces free of grease. The trickiest part of installing a range hood is determining how to run the ventilation ducts. You will need to decide if it is easier to vent through an outside wall versus up through the roof.
Locating the Position
Hold the hood up where it will be mounted and outline the location for the knockout and duct with a pencil. You should also make a corresponding outline in the top of the cabinet.
Drill the Holes
Drill holes in each corner of your outline and then use a reciprocating saw to cut from hole to hole. Repeat the procedure for the hole in the top of the cabinet and for any drywall above the cabinet. Next, cut the hole for the electrical cable by using a drill bit the same size as the knockout outline and pull your cable through it.
Positioning the Ducting
Once you have made a path to the attic you will need to make a hole in the roof. From inside the attic choose a location not far from the hood and drill a hole from the underside of the roof out. Next, cut a hole corresponding to the size of your ducting using the first hole to start the cut. If you have a tile, metal or flat roof this portion of your installation should be done by a professional roofer as special tools and techniques are needed to cut through and seal these roofs.
Installing the cable clamp
Back in the kitchen install a cable clamp in the knockout hole on the hood (red circle). Next, with a helper, hold the hood in its final position. Feed the electrical cable through the clamp and screw the hood in position below the cabinet.
Installing the duct
The next step is to install your ducting. Assemble the ducting in place, making sure to tape the joints with duct tape to prevent air leaks. Strap the duct at each join to something solid (A), such as a stud. Be careful that the damper in the hood move freely and is not obstructed by a poor fit with the ducting. Also, it is a good idea to use an adapter (B) at some point to switch from the square duct that comes out of most hoods to a round pipe that can be more easily routed through a roof.
Sealing the duct
- A. To seal around the ducting that goes through the roof, position the duct flashing over the hold
- B. Slip part of the flange under the shingles that are above the hole. Make sure to put roofing tar under the flange of the flashing before you install it.
- C. Next, slip the last section of ducting through the flashing and attach it below. Be sure to seal around the join between the flashing and the duct with roofing tar.
- D. Put a vent cap on the top of the duct.
Reinstall the fan unit, light cover, and filter. Connect the black wires together, the white wires together and the green or copper wires together or to a ground screw. Cover the wire connections with wire nuts and then cover all the wiring with the electrical housing cover. Finally, turn the power back on and see how it all works.