Especially with the studies indicating the air quality issues using a gas cooktop. An oval vent duct can run across the top of your wall cabinets.

Why are you losing cabinet space? I'm in a similar situation and the options presented to me were

#1 an elbow and run the 3"x10" duct ( equiv of 6" duct) for 4 feet along the top of the cabinets and out the side wall. Hide the vent behind 2 stage crown moulding.

#2- run the vent inside the cabinets along the top shelf. My upper cabinets are 42" tall and I don't use the top shelf.

I went with a ductless hood and it would have been better to not have any fan at all. WORTHLESS!!! Just blows around any smoke from cooking. Doesn't 'clean' the air.

There is only one answer vented when ever remotely possible . You need to post a pic of your space showing where the range is . IMO a gas range always needs a proper vented hood., Post the pics her ein a comment DO NOT start another post.

Thank you all for your feedback. i was concerned the elbow and length would make it ineffective, but this group seems to think that would be fine.

You must make sure the duct to the outside is sized properly. It needs to be 8" or 10" diameter. Do not let a builder or project manager tell you, e.g. "a 6" duct is fine". If the duct is too small, your hood exhaust's effectiveness will be curtailed, and it will be noisier, even if you bought the greatest hood in the universe.

Asking again, why would you lose cabinet space by exhausting the duct to the outside? Perhaps your kitchen design could be improved so that would not be the case.

Vented to the outside for sure.

In a conventional ducted to the outside hood, the function of the filter (e.g., baffles) is to collect grease from the larger end of the particle spectrum, and expel to the outside particulates from the smaller end of the particle spectrum, along with moisture and odors. A recirculating hood can partially capture odor and smaller particles with charcoal and other supplementary filtering materials; combustion products from gas cooking may not be adequately removed.

Duct size should support keeping the flow rate in the duct between 1000 and 2000 ft/min using circular duct equivalence size.

Non circular ducts have a circular duct equivalence given by four times the sectional area divided by the perimeter.

Hood baffles typically have higher pressure loss than reasonable lengths of ducting of the proper size. Pressure loss can almost always be made up by blower choice, so duct length should not get in the way of external venting.

To gain needed insight, please search out and review as many as you can stand of the myriad hood-related topics on this forum. There is a lot of potential complexity in choosing a hood and the make-up air (MUA) scheme needed to support the desired flow rate.

Personally, I could never use an unvented hood with gas. I suspect it is a code violation in some areas? Not sure. Gas releases a lot of contaminants into the air, not to mention the food odors and oils. Your distance and bends will not challenge a good quality hood properly installed. Good luck with your project.

You NEED a ducted hood if you're cooking on a gas stove. Not legally (I have no idea) but for your own health.....a window 4 yards away is meaningless in that respect. The carbon monoxide levels produced by a gas flame won't be enough to kill you, of course, but chronic exposure to the CO (as well as other pollutants) can exacerbate other health issues. My sister got a CO detector for her home (just an OTC microwave fan), and the numbers rise alarmingly after she's cooked dinner.

Both have their pros and cons. If you're using a gas cooktop, safety is crucial. Ensure that the ventilation method you choose is adequate for removing any combustion by-products, such as carbon monoxide, and follow all safety guidelines.

If you choose a vented hood, the window's proximity could affect the effectiveness of venting. Ensure that the window configuration allows for proper ventilation without causing issues like drafts.

It might be helpful to consult with a kitchen ventilation professional or an appliance specialist who can assess your specific kitchen layout and provide recommendations based on local building codes and safety considerations.

If you go with ductless at least condition the air.