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How to Install a Ducted Range Hood

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How to install a ducted range hood.

Required Materials

  • Flexible Accordion duct with insulation
  • Hooked blade
  • Roof-mounted exhaust vent
  • Jigsaw
  • Drill
  • Caulk gun
  • Pry bar
  • Asphalt roof cement
  • Roofing nails

Installing a horizontal range hood

For those who choose to install their wall hood in a horizontal position, there are two choices.

Option number one involves the duct going horizontally from the hood to the exterior of the home

Option number two involves the duct going vertically towards the ceiling, then taking a sharp 90-degree angle towards the wall where it is then exhausted outside.

How to Installing a Vertical Range Hood

The diagram below shows you another option for venting your wall hood through the ceiling.

You may consider a vertical configuration that vents the exhaust straight into the ceiling and out to the roof, or to the addict and continuing to the roof to exhaust the air outside. 

If you are installing an island hood, you can only use a vertical configuration. 

Only use aluminum or galvanized steel

Only use aluminum or galvanized steel HVAC ducting. Avoid flexible plastic conduit. A range hood should last 10+ years, but a flex duct will not. The rigid duct is more durable than flexible plastic ducting by far. It’s your best bet Rigid duct systems also transport air more easily than flexible duct systems, allowing all that greasy kitchen air to escape.

Choose the proper size duct

For your duct system to function well, make sure that you choose the proper size duct. Duct size is determined by range hood CFM. If you have a 900 CFM hood, for example, you should not reduce the diameter of your duct below 8”. After properly installing the duct, glue it to your hood with aluminum tape.

1. Do not exhaust into an attic or any other enclosed location

If you only follow one tip, make it this one. Ventilate your range hood outside through the ceiling or wall.

Smoke, cooking exhaust, humidity, and pollutants shouldn’t accumulate in your attic. Instead, extend the duct to the exterior. This will properly eliminate the smokey greasy excuse.

Hot air rises, thus venting vertically via the roof is ideal. But this is optional. If you can’t vent directly above your hood, use a sidewall.

2. Use no more than two elbows in your ductwork

Use no more than two elbows in your ductwork. Fewer elbows, the better. Each elbow increases resistance to your duct system, making it difficult for air to be properly ventilated. A few elbows are not a big deal and it’s very common to need a few to navigate your walls. But use them sparingly and keep the smoothness of the airflow in mind as you plan the ventilation path. 

When adding elbows to your duct, try to   Reduce the length of your duct by 5′ at each elbow. For example, a 30′ straight run is about the same as a 20′ elbow run.  Make sure to provide at least 18 inches of the straight run before adding an elbow when building your ductwork.

Make that there is a straight length of the duct that is at least 24 inches long between each elbow.

3. Route your ducting to the outside of your house as quickly as possible

Orient your ducting to use the shortest run with the fewest elbows. So the unclean air has the least resistance and may easily exit your home.  Regardless of aesthetics, the shortest and straightest ductwork run maximizes power, efficiency, and longevity.

Use no more than 30′ ductwork. The greater the length of your duct, the greater the amount of resistance it has. If your duct is longer than 30′, even a powerful range hood will struggle to get the air outside.

5. Finish the duct run with a wall or roof cap.

A cap keeps dirt out of your ductwork. It also inhibits back-drafting, presenting external air entering your ducts.

Don’t forget to apply calk around the cap to completely seal it off. This secures the cap and prevents greasy kitchen air from escaping your duct system.

How to Install a Range Hood Vent Through the Wall

How far should a range hood protrude from the wall?

A range hood should protrude at least half the length of your kitchen range, although it usually does not go all the way out.

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How much ductwork should I use?

Your range hood duct should not be longer than 30 feet for a straight run, 25 feet for a one-elbow run, and 20 feet for a two-elbow run. The conduit should be as short as possible. Your kitchen air may not reach the outside if your ducting is too long. This may result in backtracking.  Backdrafting occurs when air is trapped inside your duct and rushes back through your hood and into your kitchen.

Should I insulate my ducted range hood vents?

You can insulate your vent hood duct if you want to, but it’s not necessary. If your blower is in line with the ducting, insulating it will lessen the noise. Insulation may also help keep smoke and oily air out of your joists and attic.

Tips to consider

Tip 1: To avoid electrical hazards, turn off the electricity that is linked to the portion of the kitchen before starting anything in it. Handling electrical equipment with damp hands is likewise not a good idea.

Tip 2: Knowing what style of hood you already have or intend to buy can help you determine if you need a ducted vent or not.

Tip 3: To avoid electrical risks, check sure the socket into which your range hood vent is plugged is enough for its power requirements. Each outlet and cable’s power sufficient is generally labeled on them, so double-check.

Tip 4: Always verify your user manual or conduct research to ensure that installing the range hood vent yourself will not affect the manufacturer’s warranty.

Tip 5: Make sure the wires are separated and stripped.

Tip 6: Because you don’t want your roof to be filled with smoke, the ducts that pass through it must be air and watertight. (It will be expensive to hire an expert to repair this).

Tip 7: When it comes to ducting, we recommend using painted steel rather than plastic. This assures that there will be no leaks due to wear and tear.

Tip 8: When connecting wires, use wire nuts.

Tip 9: When venting your ducted vents, make sure you use plastic. This is due to the fact that plastics are typically lower grade. Use painted steel, galvanized steel, or metal ducting, if possible.

Tip ten: Avoid using plastic ducting or venting.

Tip 11: Use no more than 30 feet of ducting to ensure that the smoke leaves the duct readily and fast.

Tip 12: Insulate your ductwork to avoid problems with condensation or leaks.

Tip 13: It’s also a good idea to use HVAC tape to seal all of the seams.

Tip 14: To maximize airflow efficiency, don’t use too many elbows. In fact, it is recommended that you create at least 23 inches of straight vents before installing an elbow. In your ducting, no more than four 90-degree elbows should be used.

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Author avatar - Roger Harris
Written By Roger Harris
Hey there! My name is Roger, and I've been selling range hoods for over six years. I now run this blog all about range hoods and kitchen ventilation! If you're looking for a new range hood for your kitchen, this is the place for you.

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