Convertible Range Hood: Switching From Ductless to Ducted Later

Yes, you can switch a convertible range hood from ductless to ducted later, and it is a common plan for renters, new homeowners and anyone waiting on a remodel. The hood side of the change is easy. The hard part is getting a duct from the hood to the outside, which is where the cost, the permits and the “is this even possible here” questions come in.

At a glance

What makes a range hood convertible

A convertible hood is built to work either way. It has:

• A duct collar or knockout on the top or back, usually 6” round, 7–8” round, or 3¼” × 10” rectangular on low-CFM under-cabinet hoods.
• A backdraft damper, or a place to fit one, at the collar. The damper is a flap that opens under airflow and closes to keep outside air and pests out.
• A recirculating kit for ductless use: charcoal (carbon) filters and, on many hoods, a diverter or deflector that sends air back into the room through vents in the front, top or chimney cover.

If your hood only has recirculating vents and no collar or knockout, it is ductless-only. It cannot be converted, and the path to ducted is a new hood.

Manufacturers use the word “convertible” loosely, so look in the manual for installation instructions for both modes. Some hoods ship in ducted mode and need a separately sold recirculating kit; others ship ductless with parts for ducting included.

What a conversion kit includes

When you start ductless, you install the recirculating kit. When you convert, you remove it. Depending on the hood, “converting” may involve:

• Removing charcoal filters.
• Removing or flipping a diverter plate so air goes up the collar instead of out the front.
• Opening a knockout on the top or back of the hood.
• Installing a damper or a collar-and-damper assembly, if it was not already in place.
• On chimney hoods, swapping the vented upper chimney section for a solid one, if the recirculation vents were in the chimney cover.

Keep all the parts and the manual from the original install. Parts are usually available from the manufacturer if you lost them.

What the conversion work involves

Turn off power at the breaker, not only at the hood’s switch, before you take the hood down or touch any wiring.

1. Plan the duct path

The duct should run as short and straight as possible from the hood collar to the outside. Keep these in mind:

• Direction. Through the exterior wall behind the range is usually the easiest and cheapest. Up through the roof works when the range is on an interior wall. Soffit exits work in some homes if the cap is designed for it; the duct must still discharge outdoors, not into the soffit cavity.
• Length and elbows. Each 90° elbow costs roughly as much airflow as 10–15 feet of straight duct. Aim for under 30 equivalent feet.
• Size. Match the hood’s collar and never reduce below it. A 6” round duct is typical up to about 400 CFM; 7–8” for 600 CFM.
• Obstacles. Joists, studs, plumbing, wiring, windows and upper cabinets all shape the route. Check what is inside the wall before cutting.

If your duct path is long or crooked, the hood’s real airflow drops. Our CFM calculator helps you check whether your hood has enough airflow for your cooktop and suggests a duct size.

2. Make the wall or roof penetration

• Wall: cut a hole through the drywall, sheathing and siding, sized for the duct, and install a wall cap with a damper. Flash and seal the cap to the siding so water cannot get behind it.
• Roof: cut through the ceiling, attic and roof deck, install a roof cap with proper flashing under the shingles, and seal it. Roof work means ladders and a fall risk, and a badly flashed roof cap is a common source of leaks, so many homeowners hire a roofer or contractor for this part.

3. Run and seal the duct

• Use smooth rigid metal duct: galvanized steel, stainless steel or copper, as required by IRC 2021 Section M1503.4. Do not use flexible foil duct.
• Seal joints with foil tape, not cloth duct tape.
• Do not let screws poke into the duct, since they catch grease.
• Slope horizontal runs slightly toward the outside where possible so condensation drains out rather than back to the hood.
• Insulate duct that runs through a cold attic to limit condensation.
• The duct must go all the way outside. Under IRC M1503.3, it cannot end in an attic, crawl space or inside the building.

4. Convert the hood

1. Remove the charcoal filters. They restrict airflow and are only needed for recirculation.
2. Remove or reposition the diverter, following the manual.
3. Open the knockout and install the damper and collar.
4. Remount the hood, connect the duct to the collar and seal the joint with foil tape.
5. Replace the washable grease filters. Those stay in either mode.
6. Test on every speed. Go outside and check that the exterior flap opens. If it does not, see range hood vent flap stuck.

5. Check makeup air

If the hood is able to exhaust more than 400 CFM, IRC Section M1503.6 requires makeup air. A ductless hood does not remove air from the house, so this can become an issue only when you convert. Check with your local building department.

Typical costs

These are typical US ranges. They vary by region, house construction and how much finishing is needed.

A DIY wall run with materials only often costs $100–$250 for duct, fittings, wall cap and tape. The skill and risk are in cutting the exterior wall correctly and sealing it against water.

When conversion is not feasible

Conversion is not realistic in some situations:

• Condos and apartments. Many associations and buildings prohibit new holes in exterior walls or roofs, or require board approval. Shared walls and fire-rated assemblies add rules. Check your governing documents and building management before you plan anything.
• Rentals. You will need the owner’s written permission.
• Interior ranges with no route out. An island or interior wall with occupied floors above can make a duct path impractical without opening ceilings.
• Structural or fire-rated walls. Cutting through structural members or fire-rated assemblies needs engineering and approval.
• Very long runs. If the only path has many elbows and 40–50+ equivalent feet, a standard hood may not move enough air. A remote or inline blower can help, but costs more.
• Historic districts. Exterior changes may need approval.

If ducting is not possible, keep the ductless hood working well: replace the charcoal filters every 3–6 months (see charcoal filter replacement), clean the grease filters monthly with heavy use, and open a window or run a bathroom fan while cooking to help with humidity.

Performance before and after

Going ducted is a real upgrade, especially over gas. A ductless hood returns heat, moisture and combustion byproducts to the kitchen. A ducted hood sends them outside. For a full comparison, see ducted vs ductless range hood.

Once ducted, plan occasional checks on the duct and cap. Grease can build up in the duct over years of heavy cooking; our guide to grease buildup in ductwork covers what to look for.

Which should you choose?

Buy a convertible hood and start ductless if:

• You cannot duct right now but might after a remodel, a move within the building rules or a landlord’s approval.
• You want to spread the cost over time.
• You are unsure where the duct will go yet.

Convert to ducted now if:

• You cook on gas.
• You fry, sear or cook often and notice lingering smells, heat or window condensation.
• There is a short, direct path to an exterior wall.
• You are already opening walls or ceilings for other work.

Stay ductless if:

• Building rules prohibit exterior penetrations.
• There is no reasonable duct route.
• You cook lightly on electric or induction and are happy with the results.

What to look for when buying a convertible hood

• Manual lists both ducted and recirculating installation
• Duct collar or knockout on the top or back, matching your likely duct route
• Collar size you can match without reducing (6” round is common up to about 400 CFM)
• Backdraft damper included or available
• Recirculating kit included or clearly listed, with a replaceable charcoal filter
• Charcoal filters easy to find and change, with the replacement interval stated
• Washable baffle or mesh grease filters
• Certified CFM (HVI) that suits your cooktop in ducted mode, checked with the CFM calculator
• Sone rating at low and high speed
• Hood can exhaust 400 CFM or less, unless you are ready to plan makeup air

The bottom line

A convertible hood is a smart choice when you cannot duct today but may be able to later. Converting the hood itself takes an hour or two. Planning and building a clean, short duct run to the outside is the real project, and it is worth doing right with permits and proper flashing. If your building rules or layout rule out a duct, a well-maintained ductless setup is the fallback.