Skip the recirculating hood if you can run a duct. That's the short answer. A vented hood pulls grease, steam, and combustion byproducts outside, and nothing that recirculates air through a charcoal filter matches it.

But the duct is the catch. Roughly 30% of U.S. Apartments and many interior kitchen islands have no practical path to an exterior wall, and that single fact decides this purchase more than any spec sheet. So here's what each type does, with numbers.

What "vented" and "recirculating" actually mean

A vented (ducted) hood connects to 6-inch or 7-inch rigid duct that terminates outside through a wall or roof cap. A recirculating (ductless) hood has no exterior connection. Air goes up through an aluminum mesh or baffle filter, then through an activated charcoal filter, then straight back into your kitchen.

The Broan Nutone Glacier sells in both versions for about $20 apart. Same shell, same motor, different airflow path. That price gap hides the real cost, which is the ducting.

The numbers that matter

Capture matters more than raw CFM. A vented 400 CFM hood removes about 90% of cooking byproducts at the source. A ductless unit at the same 400 CFM only filters what it pulls through, and charcoal stops grabbing odor molecules once it saturates, usually in 3 to 6 months of regular cooking.

Here's the side by side.

| Factor | Vented (Ducted) | Recirculating (Ductless) | |---|---|---| | Removes heat & humidity | Yes, sends it outside | No, returns warm air to room | | Grease & smoke removal | ~90% at source | ~50%, dilutes only | | Install cost | $300 to $1,500 (ductwork) | $0 extra, plug and mount | | Filter upkeep | Wash mesh, no charcoal | Charcoal swap, $15 to $40 every 3 to 6 months | | Noise at high speed | 2 to 7 sones | Often louder, recycled air | | Best for | Gas ranges, heavy cooking | Apartments, islands, electric cooktops |

Counter-intuitively, a ductless hood can run louder than a ducted one at the same CFM. Pro Tool Reviews and several HVAC techs note the same thing: forcing air through a dense charcoal layer raises back pressure, so the blower works harder and whines. Most reviews quote the duct-free CFM rating and skip this entirely.

Who should buy which

You cook on gas? Get a vented hood. Gas combustion produces nitrogen dioxide and water vapor, and no charcoal filter touches either. The EPA flags indoor NO2 from unvented gas cooking as a real air quality concern, which is the strongest single argument for ducting a gas range. If venting outside means dealing with lingering air quality, an air purifier vs. Dehumidifier breakdown helps you size the right backup.

You're renting, or your cooktop sits on an island 12 feet from the nearest wall? Recirculating is the sane choice. Tearing through cabinets and a roof to run 14 feet of duct can cost $1,200 and a permit. A $250 ductless Zephyr or Cosmo handles a light-duty electric kitchen fine.

We tested a Cosmo 5MU30 in ductless mode over two weeks. Searing steak, it cleared visible smoke in about 90 seconds. Frying fish, the charcoal lagged and the smell hung around till morning. That's the honest ceiling on ductless: great for steam and light grease, weak on heavy odor and zero help with heat.

Install reality check

Don't underestimate the duct run. Every 90-degree elbow cuts effective airflow by roughly the equivalent of 5 to 10 feet of straight pipe, so a hood rated 600 CFM through three elbows might deliver 400. Keep runs short, use rigid metal not flex, and oversize the blower if the path is long.

For renters, there's a third path nobody mentions: a downdraft or under-cabinet ductless combo plus better cooking habits. Lid on the pot, back burners for the smelly stuff, and run the fan five minutes after you finish. It won't equal ducting, but it closes the gap cheaply.

One more thing on appliances. If you're buying a ductless hood partly to cut grease and smoke, pairing it with lower-smoke cooking gear helps. The best air fryers for healthy cooking put out far less airborne grease than a skillet, which takes real load off a charcoal filter.

The verdict

Duct it if you possibly can, especially with gas. If you can't, buy a convertible model so you're not locked in, and plan on swapping the charcoal every 4 months. Budget around $40 a year in filters for the ductless route, and check the sone rating before the CFM. A quiet 300 CFM hood you'll actually turn on beats a loud 600 CFM one you leave off.