When you cook inside on a stove, the chemical reactions that are released into the air are actually unhealthy and should be filtered away. The best was to do this is to use a vented range hood over the stove which absorbs grease and vapor when cooking and whisks it out of the house through a vent stack.
There are several different types of range hoods, the key difference being how they are mounted. Some hoods mount below cabinets over the stove, while other are placed between two wall cabinets with decorated, long vent hoods, or stacks, to conceal the duct work leading to the attic above.
If you have a ventless model already in place, before removing and reinstalling a new vented version, check with the manufacturer and see if they have a conversion option to exterior venting for it.
If the range is located along an exterior wall, the process will be much easier. If not, you will need to run duct work between the hood and a vent in the attic or to another exterior wall. For single level homes, you can run it up to the attic roof vent. However, you may have a more complicated setup as is often the case with multi-level homes, you may have to run ducting horizontally through cabinets or soffit and upper floors and ceiling joists to reach the roofline.
Most ducting used for range hoods is either rectangular or round in 5” – 6” varieties. After you purchase a range hood, read the manufacturer’s instructions to determine the recommended duct size.
This type of project typically takes a day for someone experienced with working with tools and doing home renovation projects.
Before You Begin
The following are some of the tools and materials you will need before you begin this project.
- Tape measure and stud finder
- Philips and flat-head screwdriver
- Electric drill
- Keyhole saw
- Hammer and chisel
- Caulking gun with silicone caulk
- Roofing tar
- Safety goggles and gloves
- Duct tape
- Vented Range hood
- Exterior vent cap
Before you start, prepare the duct run by joining various parts of the ducts and elbows together. The fewer elbows, the better the vent will perform. Empty any cabinets (if any) above the stove and remove any doors and shelves. Move the range away from the wall to allow space to work.
Note: You will probably have to disconnect the gas line to the stove if you move it out more than a few feet. If possible, avoid this because it will extend the project timeline.
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Removing the Old Hood and Modifying Cabinets
For the purposes of this discussion, it is assumed that you are removing and existing ventless hood and installing the new one under a cabinet over the stove.
- The first step will be to disconnect the wiring of the old hood. Turn off the power to the kitchen area at the breaker panel.
- Remove any filters or bottom covers from the hood.
- Remove any electrical tape and twist any existing wire nuts from the wire connections.
- If possible, remove the blower within the hood as this will make the assembly easier to manage.
- Recruit an extra pair of hands if possible before you release the brackets and screws that hold the vent in place. As they support the hood, remove any screws or bolts holding it to the wall. Now the entire assembly should be free to remove and set aside.
- Each new range hood will have a plastic or metal “knock outs” that you will have to remove to run electrical wires and duct work through the top of it. If you are going to be using a horizontal venting out the back of the range, remove those duct knockouts instead.
- Again with a helper, hold the new range hood back up against the underside of the cabinet and trace the knockout opening with a pencil onto the bottom of the cabinet. This is where you will cut the new ducting holes in the wood.
- Using a jigsaw, to holes in the cabinet bottom for the damper assembly that connect the hood to the ducting.
- Center the damper assembly over the holes in the top side of the cabinet bottom and trace a cut line 1/16” to 1/8” outside the assembly for clearance.
- Use a keyhole saw to cut the rest of the opening starting with the holes you drilled with the jigsaw and following the trace of the assembly.
Attaching the Damper and Installing the Hood
A damper is what prevents backdrafts from outside the house from blowing inside. Each range
- Attach the damper to the top of the vented hood making sure that the doors pivot freely.
- With the aid of someone else, hold the hood in place and mark screw locations. Remove the hood and drill pilot holes for the screws.
- Have your assistant hold the hood in place while you drive screws through the pilot holes you just drilled.
- If the version of hood you purchased has a plastic cover, clip it on now to close off the front exhaust.
- The power to the kitchen should be off if you removed an existing hood. If not, turn it off now, then reconnect the wires following the manufacturer’s instructions.
- Now reinstall the blower unit and the bottom cover plate (if any).
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Venting the Hood
Now that the hood is securely in place, it is time to vent it out of the house. If there is an exterior wall directly behind the stove, go in that direction. However, most modern homes are not setup in this manner, so it will be necessary to vent around the room or up through the attic. For the purposes of this discussion, we will assume a one story house with ducting though the attic to the roofline.
- Use the appropriate ducting to join to the top assembly of the vented hood. You may need a rectangular adapter that transition into a smaller 5” to 6” round duct.
- Using the same method you used to cut into the bottom of the cabinet, cut through the top of it with the jigsaw, through the drywall into the attic.
- Since we are vented through the attic, use straight duct lines as much as possible, but it may be necessary to use an elbow adapter to go around a ceiling or roof joist.
- Slide the ducting through the holes in the cabinet all the way into the attic until it clear the bottom shelf on the cabinet, then bring it back down a little until it attaching to the range assembly.
Venting Through the Roof
The best exhaust fan venting is through smooth, rigid ducts with taped joints and insulated to
- Now you can go up in your attic to finish the project.
- Drive a nail through the roof at the location where the ducting will exit the roof. Locate it as high as possible on the roofline, but below the ridge vent.
- Drill a hole from the underside of the roof out.
- Cut a hole the exact size of your ducting using the first hole to start the cut.
- Go on the roof to finish the seal.
- Position the duct flashing over the hole and put roofing tar on the underside of the flange, then slip it under the shingles that are above the hole.
- Slip the last section of ducting through the flashing and attach it below.
- Seal around any joints of the flashing and ducting with roofing tar.
- Put a vent cap on the top of the duct.
Go back inside and flip the power back to the range hood. Turn on the stove and boil some water. Test the fan by turning it on and going outside to see if any steam is venting from the roof. You should be able to visible see air flowing from the vent stack.
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