Not all range hoods vent outside—some recirculate air back into your kitchen instead
Range hoods come in two types: ducted hoods that push cooking smoke and steam outside through ductwork, and ductless (or recirculating) hoods that filter the air and send it back into the room. Which one you have depends on how your kitchen was built and what your space allows. Ducted hoods remove moisture and odors completely; ductless hoods trap some particles but return warmer air to your kitchen, which can affect humidity and heating costs.
The choice between them matters for how well your hood works and how much maintenance it needs. Understanding which type you have—and whether you can switch—helps you keep your kitchen comfortable and your hood running properly.
Key Takeaways
- Ducted hoods vent outside through metal ductwork and remove cooking moisture, odors, and heat from your kitchen entirely.
- Ductless hoods filter air through charcoal or mesh filters and recirculate it back into the room, trapping some particles but not moisture.
- Ducted hoods require ductwork to an exterior wall or roof and work better in most kitchens, but ductless hoods are the only option in apartments or kitchens far from outside walls.
- Ductless hoods need more frequent filter changes—typically every one to three months—because they rely on filters to clean the air.
- Converting from ductless to ducted is possible but expensive and requires running new ductwork through walls or ceilings.
How ducted hoods work and where they vent
A ducted range hood pulls air from above your cooktop, passes it through a metal duct, and expels it outside through your roof or an exterior wall. The duct is usually 6 inches in diameter and runs behind your cabinets or through your attic or crawlspace. The hood itself contains a fan motor and a grease filter that catches larger particles before the air leaves the house.
Ducted hoods are the most effective type because they remove heat, moisture, and cooking odors completely. This keeps your kitchen drier, prevents mold growth on walls and ceilings, and stops grease from settling on surfaces throughout your home. The trade-off is that they also remove warm air in winter and cool air in summer, which can slightly increase heating and cooling costs.
The duct must slope slightly downward as it runs to the outside, and it should have a damper (a one-way flap) that closes when the hood is off to prevent outside air from flowing back in. If your ductwork is poorly installed or blocked, the hood will not pull air efficiently, and moisture will linger in your kitchen.
How ductless hoods work and their limitations
A ductless range hood pulls air from above your cooktop and passes it through filters—usually a mesh grease filter and a charcoal filter—before pushing it back into your kitchen. No ductwork is needed, which makes installation straightforward and possible in any kitchen layout. The hood sits on your wall or under your cabinet, and the filtered air exits through vents on the front or sides.
Ductless hoods trap grease and some odors, but they do not remove moisture. Steam from boiling water, simmering sauces, and cooking pasta stays in your kitchen, raising humidity levels. Over time, this extra moisture can damage drywall, encourage mold growth, and make your kitchen feel stuffy. Ductless hoods also return warm air to the room, which can make your air conditioning work harder in summer.
The charcoal filters in ductless hoods become saturated and stop working after a few months of regular cooking. If you do not replace them on schedule, the hood will pull air but not filter it effectively. Many people find that ductless hoods do not reduce cooking odors as well as they expect, especially after the charcoal filter has been in use for a while.
When you are stuck with a ductless hood
Apartments and condos almost always have ductless hoods because building codes often prohibit tenants from running new ductwork, and the building structure may not allow it. If you rent, check your lease and ask your landlord before making any changes. Even if you own a condo, your homeowners association may restrict modifications to exterior walls or roofs.
Some kitchens are straightforward too far from an outside wall to run ductwork without major renovation. If your cooktop is in an island in the center of the kitchen, or if running a duct would require cutting through multiple walls or the roof, the cost of a ducted hood can be prohibitive. In these cases, a ductless hood is the practical choice, even though it is less effective.
If you have a ductless hood and want to reduce moisture, run your bathroom exhaust fan while cooking (if it is nearby), open a window, or use a portable dehumidifier in the kitchen. These are not perfect solutions, but they help manage the humidity that a ductless hood cannot remove.
Converting from ductless to ducted: cost and complexity
Switching from a ductless hood to a ducted one is possible but requires running new ductwork from your cooktop to an exterior wall or roof. This means cutting into walls or ceilings, installing metal duct, and sealing the opening where the duct exits outside. If your kitchen is on an upper floor, the duct may need to run through your attic. If it is on a lower floor, it may need to run through a basement or crawlspace.
The cost varies widely depending on the distance to the outside, whether you need to cut through framing, and whether you hire a professional. A straightforward installation on a single-story home with the cooktop near an exterior wall might cost $500 to $1,500. A complex installation in a multi-story home or one that requires significant structural work can cost $2,000 to $5,000 or more. Many homeowners find that the cost is worth it for the improved air quality and moisture control, especially if they cook frequently.
Before starting, check your local building codes. Some jurisdictions require a licensed contractor to install range hood ductwork, and some have rules about where the duct can exit (roof versus wall, distance from windows, etc.). Your contractor or the hood manufacturer can tell you what is required in your area.
Checking what type of hood you have
Look behind your range hood or underneath it. If you see a metal duct running away from the hood toward a wall or ceiling, you have a ducted hood. The duct is usually 6 inches in diameter and may be wrapped in insulation. Follow it to see where it exits—it should go through an exterior wall or roof.
If you do not see any ductwork, or if the hood has vents on the front or sides that blow air back into the room, you have a ductless hood. Check inside the hood for filters. Ductless hoods always have at least two filters: a mesh or baffle filter that catches grease, and a charcoal filter that absorbs odors. If you see these filters, the hood is ductless.
If you are unsure, look at your range hood manual or the manufacturer's website. The model number is usually printed on a sticker inside the hood or on the back. The manual will tell you whether the hood is designed to be ducted or ductless, and it will show you where filters are located if it is ductless.
Maintaining ducted versus ductless hoods
Ducted hoods need less frequent maintenance than ductless ones. The mesh or baffle grease filter should be cleaned every one to three months, depending on how often you cook. Most filters can be washed in hot soapy water or placed in the dishwasher. You do not need to replace the grease filter—it is reusable.
Ductless hoods require more attention because the charcoal filter cannot be cleaned and must be replaced every one to three months. The mesh grease filter should also be cleaned regularly. If you do not replace the charcoal filter on schedule, odors will return and the hood will become less effective. Over time, a clogged charcoal filter also makes the fan work harder and can shorten its lifespan.
For ducted hoods, the ductwork itself should be inspected occasionally to make sure it is not blocked by lint, bird nests, or debris. If the hood suddenly becomes quieter or pulls less air, the duct may be clogged. A professional can clean the duct if needed, though this is not usually necessary unless you have not used the hood in a long time or you notice a problem.
Frequently Asked Questions
Can I install a ducted hood if I have a ductless one now?
Yes, but it requires running new ductwork from your hood to an exterior wall or roof. The cost depends on the distance and complexity of the installation. If your cooktop is near an outside wall, it may be affordable; if it is far from any exterior surface, the cost can be high. Check local building codes first—some areas require a licensed contractor.
What happens if a ducted hood duct gets blocked?
The hood will pull less air, and cooking smoke and steam will linger in your kitchen. Blockages are usually caused by lint buildup, bird nests, or debris in the duct. If you notice the hood is not working as well as it used to, have the ductwork inspected. A professional can clean it if needed.
Do ductless hoods work at all, or are they useless?
Ductless hoods do work—they trap grease and some odors. But they do not remove moisture, so they are less effective than ducted hoods in kitchens where you cook frequently or boil water often. They are a practical choice for apartments and kitchens where ducted installation is not possible.
How often should I replace the charcoal filter in a ductless hood?
Most manufacturers recommend replacing the charcoal filter every one to three months, depending on how often you cook. If you cook daily, replace it every month or two. If you cook occasionally, it may last three months. The filter cannot be cleaned—it must be replaced when it becomes saturated.
Does a ducted hood make my heating and cooling bills higher?
Yes, slightly. A ducted hood removes warm air in winter and cool air in summer, which means your furnace or air conditioner has to work a little harder to maintain the temperature. The effect is usually small, but it is noticeable in very cold or very hot climates. A ductless hood returns filtered air to the room, so it does not have this effect.