--- title: "Ducted or Recirculating Hood: What Leaves the House and What Stays" description: "Where the air goes after the grease filter, what charcoal can and cannot remove, what converting a hood involves and the places a duct must never end." url: "https://rangehooderepair.center/guides/ducted-or-recirculating-hood/" date_modified: "2026-09-26" --- Choosing and comparing # Ducted or Recirculating Hood: What Leaves the House and What Stays A ducted or recirculating range hood differs in where the air ends up. Ducted, the blower sends heat, moisture, smoke and gases outside through metal duct; recirculating, it passes them through a charcoal filter that removes odors and returns the rest to the room. The Home Ventilating Institute says recirculating hoods provide no actual ventilation. By [RangeHoodeRepair.center technical team](https://rangehooderepair.center/authors/technical-team/) Published September 26, 2026 ## At a glance. One hood pushes the cooking air through a metal pipe to the outdoors; the other scrubs the smell out and hands the same air back to the kitchen. Which of the two you live with decides how the room feels on a night of searing, and how much upkeep the hood asks for afterward. Read the whole guide ### What recirculating removes Odors, through activated charcoal Heat and humidity come back into the kitchen. ### HVI's view Recirculating is not ventilation The institute recommends hoods that vent directly outside. ### Duct material Metal only Hood manuals rule out venting into walls, attics, crawl spaces or garages. ### Convertible hoods Need a separate kit Many hoods ship ready for a duct and take a charcoal filter bought on its own. In this guide 1. Where the air goes in each setup 2. What ventilation and air-quality authorities say 3. Convertible hoods and what switching involves 4. When a duct route is not possible 5. Differences a household notices within a month 6. Questions ## Where the air goes in each setup Both kinds begin the same way: the blower draws the rising plume through a grease filter on the underside of the canopy. From there the paths split. A ducted hood drives that air up or back into a sealed metal pipe that ends at a cap on the roof or an outside wall, and the kitchen loses the heat, the steam, the smoke and whatever the burners gave off. A recirculating hood, sometimes sold as ductless or duct-free, sends the air through a pad or cartridge of activated charcoal and out of slots near the top of the hood, back into the room. The charcoal holds on to smells. It does nothing about the moisture that fogs a window or the warmth that builds up above a busy cooking surface. ### Where the charcoal sits On most hoods the charcoal filter is clipped behind the metal grease filter or set into a housing just above it, so the grease filter protects it from fat. On a chimney hood it may sit higher, at the outlet of the blower, and on some island models it lives inside the decorative flue. The owner's manual shows the position, and the position matters: a charcoal filter left in a hood that is actually ducted only chokes the airflow. ## What ventilation and air-quality authorities say The Home Ventilating Institute puts it bluntly: nonducted, recirculating kitchen hoods provide no actual ventilation, and for the best kitchen air it recommends hoods, fans or downdraft exhausters that vent directly outside. The EPA's guidance on combustion pollutants says a hood with a fan vented to the outdoors greatly reduces exposure during cooking. ENERGY STAR builds the same preference into its certified new homes and apartments, which include a range hood or kitchen exhaust fan vented straight to the outdoors. Its reasoning names what cooking releases: particulates and humidity from every kind of cooking, plus carbon monoxide and nitrogen dioxide when the appliance burns gas. ### Gas burners tip the balance Charcoal is sold to absorb odors, yet the three bodies above still point to a duct to the outdoors when the question is combustion products. Over gas burners, the argument for a duct is therefore stronger than it is over an induction or electric surface, where the main complaints are smell, grease and steam. If a duct is at all possible above a gas cooking surface, it is the setup we would choose for our own kitchens. Source: [Home Ventilating Institute — How Much Ventilation Do I Need?](https://www.hvi.org/resources/publications/home-ventilation-guide-articles/how-much-ventilation-do-i-need/) — Nonducted, recirculating kitchen hoods provide no actual ventilation; HVI recommends hoods that vent directly outside; [US EPA — Sources of Combustion Products](https://www.epa.gov/indoor-air-quality-iaq/sources-combustion-products) — A hood with a fan vented to the outdoors greatly reduces exposure to pollutants during cooking; [ENERGY STAR — Indoor Air Quality Features of certified homes](https://www.energystar.gov/newhomes/features-benefits/indoor-air-quality-features) — Certified homes include a range hood or kitchen exhaust fan vented directly outdoors; cooking emits particulates and humidity, and gas appliances carbon monoxide and nitrogen dioxide Close on a round charcoal filter clipped to the blower inlet of a recirculating range hood. ## Convertible hoods and what switching involves Plenty of hoods can run either way. Broan's BXT1 under-cabinet series, for example, is sold as a four-way convertible: vertical or horizontal duct, or non-ducted with a separate filter that is bought on its own. For the non-ducted setup its instructions have the installer remove the damper and duct connector, open a trap door and clip the charcoal filter to the back of the aluminum grease filter. Switching is therefore more than dropping a filter in. The damper that stops outside air from falling back into a ducted hood has to come out, or it will block a recirculating one, and the top of the housing has to be closed where a duct would have attached. ### Buying the right kit Charcoal filters are specific to the model and are listed by part number in the manual or on the parts page of the maker. A filter that fits loosely lets air slip around it, and one that is too thick can press against the blower inlet. Write the part number inside a cabinet door the day the hood is installed; it saves a search every few months. Source: [Broan-NuTone — BXT1 Series 4-Way Convertible Range Hood installation instructions](https://broan-nutone.com/getmedia/e05acdba-b6be-4e9e-8182-e44db1a97192/Installation-Guide-BXT1.pdf?ext=.pdf) — Ducted or non-ducted installation; the non-ducted filter is purchased separately; for non-ducted use the damper/duct connector is removed, a trap door opened and the filter clipped to the back of the aluminum filter ## When a duct route is not possible Recirculating exists because some kitchens simply cannot vent outside. The choice usually follows the building rather than the owner's taste, and a few situations push hard one way or the other. - An apartment or condominium where exterior walls and roofs belong to the association: recirculating, unless the board approves a penetration. - An interior island with a finished ceiling and floor joists running the wrong way: a duct may be possible through the joist bays, or may not be. - An under-cabinet hood on an outside wall: a short run straight through the wall is usually the easiest duct there is. - A remodel that already opened the ceiling: the cheapest moment there will ever be to add a real duct. - Heavy wok cooking, searing or frying most nights: worth a serious effort to get the air outside. ### Places a duct must never end Vent-A-Hood's owner guide, like most hood manuals, says ducted fans must always vent to the outdoors and never into spaces inside walls or ceilings, or into attics, crawl spaces or garages. The same guide asks for metal ductwork only, to reduce the risk of fire. A duct that stops in the attic is not a compromise between the two setups; it is grease and moisture delivered to the framing of the house. ## Differences a household notices within a month The comparison on a spec sheet is airflow and noise. The comparison in a lived-in kitchen is different, and most of it shows up quickly. - Warmth: a ducted hood carries the heat of a long simmer out of the room; a recirculating one leaves it hanging at head height. - Windows and cabinet faces: moisture from boiling pasta condenses in a recirculating kitchen, especially in winter. - Upkeep: both need clean grease filters, but only the recirculating hood adds charcoal that has to be bought and replaced. - Sound: air pushed back through a charcoal pad and out of a grille can be louder at the same fan speed. - Drafts: a ducted hood can let cold air in through a damper that does not close, which a recirculating hood never does. ## Where to stop Cutting a new opening through an exterior wall or roof, or moving a duct through joists, is contractor work with its own permits. Inside the hood, converting the blower's outlet or reaching the damper on a chimney or island model means removing covers above the canopy, which is our job rather than an owner's: nobody should climb inside a chimney cover or open the blower housing. A hood that trips a breaker, smells hot or sparks during a conversion needs the breaker off and a visit. Written by [RangeHoodeRepair.center technical team](https://rangehooderepair.center/authors/technical-team/). The crew that fixes kitchen range hoods here, writing from its own service visits and each maker's installation papers. Sources: [Home Ventilating Institute — How Much Ventilation Do I Need?](https://www.hvi.org/resources/publications/home-ventilation-guide-articles/how-much-ventilation-do-i-need/) · [US EPA — Sources of Combustion Products](https://www.epa.gov/indoor-air-quality-iaq/sources-combustion-products) · [ENERGY STAR — Indoor Air Quality Features of certified homes](https://www.energystar.gov/newhomes/features-benefits/indoor-air-quality-features) · [Broan-NuTone — BXT1 Series 4-Way Convertible Range Hood installation instructions](https://broan-nutone.com/getmedia/e05acdba-b6be-4e9e-8182-e44db1a97192/Installation-Guide-BXT1.pdf?ext=.pdf) · [Vent-A-Hood — Owner and Maintenance Guide for models with the Magic Lung blower](https://www.ventahood.com/manuals/Magic%20Lung%20OMG.pdf) For the heart of your home. ## Questions owners ask. ### Is a recirculating hood better than no hood at all? Yes. Its grease filter still catches fat before it settles on cabinets, and the charcoal takes out a good share of the smell. It simply does not remove heat, moisture or combustion gases. ### Can I run a ducted hood with a charcoal filter as well? Only if the manual allows it. On a ducted installation the charcoal adds resistance and cuts airflow without any benefit, so most manufacturers leave it out. ### How do I tell which setup my hood has? Look for slots or a grille near the top of the hood blowing air back into the room, and for a charcoal pad behind the grease filter. If neither is there and air is felt at an outside cap when the fan runs, it is ducted. ### Does a ducted or recirculating range hood need more service? The motor and controls wear at about the same pace. The recirculating hood adds charcoal changes; the ducted one adds a damper and an outside cap that can stick or clog. ## The problems behind it. Each has a page of its own: what it usually means and the causes in the order worth checking. [All 17 problems](https://rangehooderepair.center/problems/) Problem ### Range Hood Runs but Barely Pulls Smoke 7 causes, cheapest first Problem ### Cold Draft or a Flapping Damper Through the Range Hood 6 causes, cheapest first Problem ### Range Hood Too Loud: Roar, Whine or Grinding 6 causes, cheapest first ## When it needs a technician. The repairs on the right are where this guide ends when the checks do not settle it. ### Range hood damper and duct repair Getting the air out of the house: the backdraft damper, the duct and its joints, the wall or roof cap, and make-up air in a tight house. ### Range hood filter and baffle service Cleaning or replacing what catches grease and odor: mesh and baffle filters, charcoal pads on recirculating hoods, and the grease channel. ### Range hood diagnostic visit A visit that runs the hood through every speed and light, tests the draw at the filters and follows the air outside until one part is named. ## More in choosing and comparing. Wall-mount, under-cabinet, island or an insert in a custom hood, ducted or recirculating, and when an aging range hood deserves a repair and when it is time to buy another. [The whole section](https://rangehooderepair.center/guides/choosing-and-comparing/) Which hood, and fix or replace ### Wall, Island or Insert: Picking a Range Hood Shape That Catches the Plume Chimney, under-cabinet, island canopy, custom-hood liner and the downdraft vent compared on airflow per foot, mounting height and how each is reached for service. Which hood, and fix or replace ### Repair or Replace a Range Hood: The Shell, the Part and the Woodwork Around It Why a sound body usually means repair, which parts are routine and which bodies are not worth saving, and why an insert in a custom hood leans hardest toward fixing. Guides ### All 18 guides Six sections, by what you are trying to find out. --- **[Read on the site: Ducted or Recirculating Hood: What Leaves the House and What Stays](https://rangehooderepair.center/guides/ducted-or-recirculating-hood/)** **[Book a visit with RangeHoodeRepair.center](https://rangehooderepair.center/schedule/)**