What type of cooking do you typically do, what are your local codes re venting cooktops and are you willing to post your existing and proposed plans?

Mostly sautéing, steaming, stir fry. I assume we’d be within code since my GC says it’s all feasible. I don’t have my existing floor plan, but I’m attaching 1) the first proposal which keeps the stove top where it was with a downdraft. And 2) second proposal where the stove top is moved to the wall shared with a hallway - this would require a ductless hood.

This is the first proposal

This is the second proposal:

Second plan is far better, but hard to say without a floor plan of the entire space/ knowing where the hallway wall terminates to an exterior ........and how far.

Depends the amount of stir frying : )

"With no easy access".................well. That's a LOT of refrigeration.$$$$$ The hard way may be the better way .

Stir fry qualifies as 'hot' cooking in the oil vaporization temperature scale. It requires a large enough capture area to encompass the expanding cooking plume (plus deviations due to drafts) and an adequate air velocity to ensure containment by the hood baffles (approximately 90 ft/min across the capture area). Hot cooking also puts the greatest load on any recirculating hood filters that must clean the air of grease and oil before inserting it back into the kitchen. On the other hand, recirculating avoids make-up air system issues.

The only recirculating hood we have received significant feedback on here is the VaH ARS. It is large and expensive. A link you may wish to peruse is: https://www.houzz.com/discussions/2347276/vent-a-hood-ductless-ars-range-hood-update#n=65

Alternatively, if there is room in the floor plan, you might consider thickening the wall behind the cooktop significantly, either along the entire wall or just behind the cooktop such that one has a vertical soffit (a chase) that leads to a possible underfloor path. I don't think less than 8-inch duct would be suitable for stir frying, although a noisy high pressure loss blower operating through 6 inch duct might be functional -- air flow wise. A soffit for a ceiling run is also worth considering and better than a 180-degree turn from hood to underfloor.

Rectangular duct may provide some pressure loss advantage for a given limiting dimension, but note that the round duct equivalence formula is: (equivalent round diameter) = 4 x (sectional area) / (perimeter). Symbolically, d = 4ab/(2a + 2b). where a and b are duct side dimensions. [IRC Table M1506.2]

IMo you always try to design to have a cooking appliance on an exterior wall and without any info as to where this space is in your home I have no clue as to what would be a great layout. I think downdrafts are pretty close to useless in most cases and for stir frying completely useless. Even with a 1200CFM hood vented straight up through my roof I still get grease on the wall behind my range and I can't imagine how yucky that would be with no proper venting. I have a 10" vent BTW. I have no info as to the size of your family so can't comment on frdge spac but I tun a catering biz from my home with a lot less fridge space. BTW induction is not great for stir frying in my experience and the fact that the wok needs to be flat bottomed and cast iron to really even begin to work is not ideal IMO since a light weight, round bottom wok is the perfect cooking tool I still prefer gas for my cooking. If you post a to scale plan here showing all windows doorways and how this space connects to the rest of the house you might get some really good help.

Reconsider the Hat to Cattle ratio.

There are many routes to ducting to the exterior. Place the kitchen within the context of the whole home. Post the whole home layout, with the kitchen indicated. Where is the exterior in relstionship to the kitchen?

Thank you for the feedback so far! I’ll see if I can come up with a drawing and post here. From the second proposal as reference, the wall behind the stove is a long hallway. On the other side of the hallway is the formal dining room, bedroom, and laundry room. So the exterior wall is on the other side of those rooms. From the second proposal, the wall of cabinets/refrigeration, is a large great room. The kitchen island will be facing our breakfast nook which has bay windows against our patio. Facing the bay windows, the left side of the kitchen is the family room.