Venting A Range Hood

DEAR MIKE: I have a range hood that is a piece of trash. When I turn it on, it sucks the air in and spits it right back in my face. The hood sits on an exterior wall, but I want to change it so that it exhausts outside instead of inside. How can I do this? -- Rob P.

DEAR ROB: Back in the day, range hoods were vented outside. Most new homes, however, are not.

I remember getting off the school bus and walking past Gorgeous's house. Somebody called her that not because of her looks, but because of her spaghetti sauce. Her range hood would blow the smell of that ambrosia all over the neighborhood.

Cheap hoods exhaust air back into the house. They use a charcoal filter that is supposed to trap odors and return the air inside.

Other range hoods are ducted at the top and let you choose whether to exhaust the air back inside the house or upward to duct work that will carry the air outside. If you don't have this type of hood, you will need to buy one (they start at around $60).

If you look in the cabinet directly above the hood, you will see an electrical outlet into which the hood will be plugged. You may have a hole already cut in the bottom of the cabinet which gives access to the opening in the top of the range hood. If you don't have a hole, you will need to cut one.

You must remove the hood (there are only four screws) to cut the hole. Remember to unplug the hood before moving it. Eyeball the duct port in the top of the hood and cut the hole. The position of the hole doesn't have to be perfect because the hood will cover it anyway. Drill a starter hole and use a jigsaw to finish.

The most challenging part of this job is cutting a hole in the wall of the house. You want to avoid damaging obstacles, such as wall studs, firestops, wiring, etc. The cabinet doors will hide any holes you make in the wall.

Use a studfinder to see where the framing is located. Use a drywall saw and cut shallowly. Start with a small hole and look to see if the hole would be a suitable location, that is, there are no wires or other obstructions.

Locate the hole first, then worry about getting the duct work to it. Ducting comes in all shapes so that part of the job is simply mapping it out.

Once you are satisfied with the location of the hole, cut it to a 4-inch diameter. Since this is an exterior wall, you will encounter insulation, sheathing, and then stucco.

Put a glove on and push the insulation to the perimeter of the hole. Use a drill and a masonry bit to burrow through to the outside. Drill a series of holes to outline where you will need to cut. You can use a reciprocating saw with a demolition blade in it to cut the hole in one swipe. If you don't have one, you can chisel out the stucco and then muscle out the sheathing by drilling holes around the perimeter or continuing with a drywall saw or jigsaw.

Now it's a matter of connecting the duct work. Buy a wall vent. This is what you will see from the outside. It is a short length of ducting with a hood over it to deflect rain. Make sure it has a screen over it or that it is louvered to keep out any critters.

Squirt construction adhe- sive behind the vent and push it through the hole. Hold it in place by screwing it into the wall. Caulk around the edges to keep out the outside air.

>From the inside of the cabinet, it's a matter of buying some different fittings and lengths of duct work. Also buy some self-tapping sheet metal screws and some foil tape.

You can cut the duct work with metal snips but be careful because the cut edges are razor sharp. Connect the duct work together by pushing the crimped end of one piece into another piece. Screw it all together and wrap the connections with the tape.

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