Skip the gas entirely. It only adds to the heat load. A single 30” induction cooktop will do everything you need, and not add pollution and a lot of bypass heat to your home. (8” is way out of proportion to any landmark building kitchen size.

Thanks for the advice. I still need the hood.

I think you might have a hard time finding a ductless hood rated for gas below, plus you'll need minimum 30" between the cooking grates and the hood to meet code for safety reasons. If you really want gas, check with the manufacturer of the cooktop or range to see what they recommend. Lighting is also important, most hoods come with bright LED lighting now, so that will help. Otherwise, add more lighting from the ceiling on both sides of the cook area.

The answer to your question depends on how seriously you take the negative health impacts of air pollution.

Since you want to put a gas cooktop in a kitchen with no extraction vent, I'm thinking you don't take it too seriously, so you may as well go ahead and put a recirculating vent hood underneath cabinetry. This is your cheapest and least effective option.

If you are concerned about protecting your health from the air pollution that the gas cooktop will definitely spew into your home (combustion byproducts are no joke), I'd recommend ditching the gas cooktop (going all induction, as live_wire_ oak recommended above) and installing a Vent-a-hood ARS hood. This option would best protect your air quality, and the health of those breathing it.

Thanks to you all. I had no idea that there was any problem with a gas cooktop. I live in NYC, and have always lived around gas ranges (totally unvented, not even by windows where I am putting mine). I would still like to have something approximating 6 burners...Is there an induction cooktop you would recommend?

Bosch flex induction gives you lots of flexibility in 30” range. I did get the Mansoon under]cabinet vent because food gets hot and I’ll be in a humid climate. Bail on gas given your situation and cook like the top Chicago Michelin Star chef Greg Aschultz using only induction.

Never had 6 burners, but I currently have a portable/plug-in burner that I use all the time, instead of the gas range I have! I will look at all of these. Thanks again!

There are lots of recirculating fan options that are available these days, so it’s really up to you what form you want it to come in. And there’s nothing wrong with installing a gas cooking surface under a recirculating fan, btw.

Sammy, I used to think the same as you, and cooked on a gas range under a recirculating microwave hood for 7 years -- until we had disastrous health impacts for our child. We learned the truth too late: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4050506/

Don't do it, if you care about the health of you and your family.

Windows that open are not going to work with a gas range for sure .

Thanks to all! Going with a Wolf 30" induction cooktop an a 15" two-burner gas unit combination. I plan on using the induction predominately (maybe completely), but am a little scared about not having the option for gas in a pinch. I appreciate your nudge to go this way!