Post a layout of the unit. I’ve run ducts on top of cabinets, inside cabinets, and created soffits before. But your run sounds really convoluted. Let’s see the kitchen, and it’s position within the unit as a whole, and where “outside” actually is. Post all floors too. Up and out is always the best if it can be managed through a chase in a closet or something.

Does this photo help?

There is no way to go up and out due to second floor design. Trying to make a run to the left of the left of the stove to an exterior wall entails going through two rooms.

Plan would be to have ductwork going straight up from new range hood

and then take a 90 degree turn at ceiling. In the kitchen it would be concealed by cabinetry and in the adjoining den, it would be concealed by a newly built soffit before it vents out through the exterior wall. Or, should I just give up this thought and do a re-circulating?

Thank you.

Seeing the photo it is a lot more direct than your description. If a hood is that important to you I think go for it. Remodeling is always about trade offs, I would probably opt for a recirculating hood because I wouldn't want the soffit in the lr, unless I was building cabinets there too...

Are there no exterior walls in the kitchen . Post a few more pics of the space.

"in fact, the entire kitchen is interior with no exterior wall"

Geez, people, read the post. The OP's description was exactly as the photo shows, and it did not sound convoluted, nor was it hard to understand at all. Some posts are very difficult to understand, but this one was not.

As long as the soffit is in the corner and not through the middle of the den, I think it would look fine.

Your setup looks similar to ours, except we are the end unit, so I was able to easily vent to the outside.

Have you considered, or would it be possible, to re-orient your kitchen? Say, run your kitchen along the wall toward the back of your unit, with the sink in an island? I ask because newer versions of our townhouse have that setup: open plan with the kitchen along the side wall.

/\/\/\ You REALLY want to spend the OP's money! Sounds nice though!

You lose efficiency with length and with turns, but maybe you could do an arched bend and then straight on out -- is that what you had in mind, or another bend to get from back of cabinets to side wall of LR? Of course that can be soffited. I have something similar that I added for my dryer to vent. Sounds like you'll lose the top shelf of a whole set of cabinets, though -- maybe not a crisis if it's a shelf you don't even have currently.

Check out in-line blowers, too, if the hood fan needs a boost.

Without knowing what the exterior wall is, I see no impediment to this long run (measured in likely duct diameters). It has only two ells, if I read the description correctly.

To compensate for duct losses one can go up in duct size.

One can choose a blower that has a higher zero static pressure flow rate. If this is not available in the selected hood, then it will be available in an external blower. Note that an external blower is most conveniently wired to the hood, and thus has to be compatible with the hood fan control. Some hood sources (e.g., Wolf and Broan) have this capability.

Keep in mind that hood filtering is mainly effective against the larger end of the grease particle spectrum and normal kitchen ventilation is intended to blow the rest out of the residence. However, some will condense on the duct walls. In your case this will likely just harden up over time. It is possible, however, with long horizontal runs to get pooling that will eventually drip somewhere. Tape your duct interfaces and if possible, provide access outside or inside for cleaning. I don't think this is a serious worry, but some planning ahead is always good.

We cook but not lots of heavy-duty cooking with strong aromas, and we don't do much frying at all.

Have you priced out this option? Just reading it makes dollar signs roll in front of my eyes, lol.
Building a soffit in a room with an 8' ceiling seems, um, a bit awkward? I'm very familiar with these Florida kitchens and 8' ceilings and struggling right now myself with trying to "fix" one in a townhouse/villa we're considering (one can dream and buy many houses while stuck at home).

I currently have a recirculating hood and don't cook much (at all). Yesterday when the grandsons decided they had to have pizza they found in one of the freezers and son-in-law decided it had to be cooked on the oven racks, not on trays, the smoke smell built up. Popped out hood and it was presto gone fairly quickly.

I'm guessing you'll also have to get approval from the association to install an external vent. And think of your nearby neighbors who might not want to smell your strong cooking smells.

Yes, we will need association approval and that also throws a crimp in possibilities.

I just wanted to know if my idea is even doable physically (sounds like it is). Then, of course, cost comes into play. There are no good solutions in our scenario, and I am trying to find the balance between cost and utility and aesthetics and hassle. Thanks for all the comments.

I should say that we recently purchased and moved in. This is basically in as-purchased condition (except for the kitchen ceiling that had to be opened up for some upstairs plumbing work), and even the current non- decorating is only at the level of, "hmmm, there's already a nail on the wall in this place and I have a picture I need to get off the floor, so I guess I'll just hang it there for now."

I built a custom duct going through back wall and outside. Converted a 6” round to 4x10 to go around a discharge pipe and get around the framing without making the soffit come down too far.

Thank you for the photos!

It’s a 45 degree soffit coming from the kitchen and into this room then going outside. It was the best option with no optimal solutions.

"It was the best option with no optimal solutions."

Pretty much true of all renovations, at every scale, as well as every product or system of interconnected products that was ever successful. So no need to apologize.

jschlesi--

Do you happen to have any photos of the finished soffits in the room?

Here. Used the space for speakers