gigelus2k13 is 100% correct. You need an 'overhang' (wrong word?) component, or some kind of fins or a sheet of glass or metal that will trap in and guide the fumes to the blower. Think CFM, (940 is probably enough) Island installation? Do not forget the secondary, but still very important job of a hood: Lighting! Really, really important second job of a hood.

@gigelus2k13: thank you for the advice. so you think i should really get that overhang thing? my husband always bangs his head on our existent one so he is INSISTING that we come up with a solution that's either really high (he is 6'5") or doesn't have that ledge overhang... and both seem fairly inefficient in terms of trapping the mist.

@AreBe: thanks! i think we are okay with the lighting and since it's an open plan kitchen that you see immediately as you walk into the apartment, the aesthetics are quite important in addition to function...

Help! Calling Dr. Kaseki on line 3...

On a serious note, you are in a tough spot. The height requirements impact the hood effectiveness and/or make the solution expensive. To have the tall cook completely avoid hitting his head against the hood, the hood bottom will sit at about 40~41" above the cooking surface, which is impractical.

Most canopy-styled hoods with good extraction properties are 24 or 27" deep, so they will be a little recessed w.r.t. the cooktop. The cook will have to bend forward to hit the hood if it's been installed low enough to be effective (32" max).

There have been a number of discussions in this forum regarding just this issue. Here is one.

Or can you make the cooking surface higher, which allows you to make the hood higher?

Just saw a 'flat' to the ceiling hood in a Houzz article you might want to look into.
https://www.houzz.com/magazine/kitchen-of-the-week-tile-sets-the-tone-in-a-modern-farmhouse-kitchen-stsetivw-vs~49071482

Best website:
http://www.bestrangehoods.com/store/products/productdetail.aspx?id=b7b66c7a-8d84-42b8-99f3-1630e77c7102

@gigelus2k13: thanks for the link and for the information! i think the hood has to completely clear my husband's head for him to be happy. he's managed to bump his head so many times on all sorts of light fixtures, range hoods, doors, cabinets, etc...

per @kristensgc's advice, we have thought about making the counter taller if it doesn't become too expensive with our (ikea) cabinets.

@Maine Susan: this i an awesome idea! does that actually work? i am mostly concerned about bacon grease and smell. i can clean off the grease but i would hate to have the place smell like bacon (or fish) hours after we cook...

Commercial hoods are typically set at seven feet above the floor (48 inches above the cooktop)! They also overlap the cooking zone by a sufficient amount to still perform needed capture. Flow rate (CFM) is also higher so that the needed velocity at the baffles is sufficient for containment.

For a case like this, I would recommend a hood that overlaps the pans by enough that at the hood height, the extreme angle from the pan edge to the hood aperture (capture area) edge is at least 10 degrees. To put it another way, no ray up to ten degrees from vertical from any pan to be used on any burner misses the hood aperture. (When against a wall, this mainly applies to the sides and front.) Meeting this criterion above 36-inches may require a non-standard hood size. Several manufacturers including Modern-Aire can supply residential acceptable hoods in non-standard sizes. (Also please see my favorite link for custom hoods below.)

Once the hood size is determined, to achieve the desired 90 cfm/square foot of flow rate calculate the aperture area in square feet and multiply by 90 cfm. This is the desired actual flow at full power. Rated blower flow rate will have to be higher because any real system will have some restrictions. (Review the myriad threads here addressing this topic.) A value of 1.5x the flow rate calculated should cover many sins. Note that at higher flow rates house leakage (unless your house is over 20k square feet) is unlikely to be sufficient. In some temperate locales, open windows will suffice; other locales require tempered air, or at least heated air. Make-up air is a large topic of its own that can also be searched here.

kas

http://www.handcraftedmetal.com/

As you have a gas cooktop, an often ineffectual downdraft system is out, (an interesting, if not necessarily a good idea.) Hmm... get a narrower hood with more CFM? Bad idea but might be an answer... so, stupidly, maybe illegally, get 1,000 CFM in a 30" hood? May not solve the problem and might be a really stupid idea. Hmm, maybe think of a hood based on a wall installation?? downdraft-- so crazy it just might work Faber makes one SCIR3008SSRB

Then you just stick an ordinary kitchen ceiling exhaust fan as back -up and to cover up the hole.

@kaseki - wow, that's a ton of information for me to research! thanks so much!

@AreBe the hood is over an island so I can't really attach it to a wall :( good idea though!

I think I am strongly leaning towards a ceiling-mounted Best brand range hood. I believe we have an outside vent so hopefully that would work. The ceiling is already a bit dropped in that area to accommodate a nearby A/C vent so I think we might be able to do this.

Any issues I should be aware of with a ceiling-mount vent? Our ceiling heights are 117" and we'll mount the stove top a bit higher than usual. I am working on the exact drawings.

As discussed many times already in this forum, the island placement has the additional disadvantages of being prone to cross-drafts and of not benefiting from the plume channeling created by the back wall and side cabinets.

The three elements that matter most are hood aperture (the total area that collects the exhaust), CFMs and distance between the cooktop and hood. Whatever you're choosing, it must drop down from the ceiling, as the distance aspect cannot be ignored. If the cooktop surface is higher than the typical 35-37", then this will help with the tall cook issue. Overall, the bottom of the hood will be no higher than 6'5" from the floor (77"), which means that the hood body and duct must be 40" lower than your 117" high ceiling. Plan for that.

BTW, the Broan hood listed earlier in this thread is just as ornamental and ineffective as the Futuro ones; they didn't even bother to list in the specs what kind of filter it has. "Italian design" means nothing w.r.t. the performance as a hood and you want one that does its job, not eye-candy.

you ask... Does that flat mount exhaust vent work??? On the link posted, the homeowner says it does for her. Perhaps there are reviews for it on purchase site? Your situation seems unique... and cook height problem. Really had never seen or heard of that vent before, just passing along the idea... good luck!
It seems stove venting is not just a complication for me (and you) but for many!!! Efficiency, looks, space requirements even cook height... on n on... can we trust what the stove people say... the vent people, one would hope so... sighs

I have a 48 " best hood and a tall husband, he had no issues cooking and hitting his head

@peasblog is your hood flush with the ceiling or chimney-style?

@gigelus2k13 Futuro 14" hood that I linked to in my first post has 940 CFM. That seems like a sufficient amount if we only have one burner operating at a time? And I doubt that would list CFM if it didn't actually work? (but, it is my first major renovation...)

flush

A flush mount ceiling "hood" is only a room ventilator unless it is large enough to capture the rising and expanding effluent without the effluent hitting the ceiling and dispersing. While 90 cfm/sq.ft. might not be needed at the ceiling due to effluent rate of rise slowing down some as it cools, I wouldn't go lower than that for a zero static pressure blower requirement. I would also expand the angle from 10 degrees to maybe 15 degrees to deal with further spreading with the slow down and light cross drafts.

This size requirement might be met with two of the flush ceiling fixtures. Note that all of this is based on hot surface cooking -- frying and grilling. If you only make omelets or simmer pre-cooked sausage, the rising velocity is much lower and the ceiling scheme, while still needing significant size, may not need more volumetric flow rate than a smaller normally mounted hood intended for the same cooktop size.

A consideration that we have addressed here in the past is the ventilation need for wall ovens that are not located under the cooktop hood. When cooking meat and opened they will spill effluent into the kitchen where it will go everywhere, including rising to the ceiling. One need not be too prissy about the cooktop effluent spillage if such a source of greasy air is commonly being emitted outside the control of the hood. While I have a separate flush mount ventilation system above my oven stack, I would rate it as less than adequate in many conditions. Hence, a ceiling register type "hood" might be expected to be marginal for a cooktop, but would aid, albeit marginally, oven effluent capture.

Commercial kitchens for which the ceiling has to be the ventilation capture and containment point use perforated ceilings and intense UV above the ceilings to neutralize the grease in the volume that is connected to the exhaust duct. (Air velocity above the ceiling is not high enough to keep the grease suspended. On the kitchen side, routine ceiling cleaning is necessary.) Such a system is way out of the class of residential kitchen ventilation, unless one maintains full time kitchen drudges among his staff.

kas

You might want to download this Yale Ventilation Guide...
http://blog.yaleappliance.com/ventilation-buying-guide

@urchinlulu: IMO you have the wrong impression that the range hood is similar to a vacuum cleaner in the sense that it will suck the rising plume and change its natural trajectory before the effluent hits the hood (e.g. white cylinder) rim.

Unfortunately it doesn't work like this. To understand why, assume that the plume is generated from a single point on the cooking surface. When it goes up, it expands at an angle of 10 to 15*; let's assume 10*: at a distance of 40", the plume will have a diameter of 14", which is pretty much the size of the white cylinder. Even if you're using a small, 6" pan, some effluent will miss the cylinder, continue up and finally get deposited on the ceiling and hood's outer surface. Not good.

In the end it's just about physics:
a) you measure what will be the cooktop area emitting the smoke and grease fog
b) you decide how high the hood must be
c) from a and b you determine the hood size, assuming a 10* outward plume spill
d) from c and 90ft/min airflow requirement you determine the CFM needed
e) from d, you apply a correction factor of 130-150% and get the CFM your hood of choice must list.
There is no way around this. c) and e) give you the two parameters you have to look for when selecting your range hood. The only two factors that can affect the computations above are: low heat cooking needs less than 90ft/min but the plume expands outwards more than 10* and various hood designs (baffles vs. aluminum mesh, VAH, duct size and length etc) affect the 130-150% (i.e. the lower the pressure drop, the less oversizing is needed).

HTH

@gigelus2k13 - thank you for the thorough explanation! Your last comment made things so much simpler. Why don't range manufacturers explain it in those terms? Lol.

So if I am willing to deal with ceiling grease and smoke deposits, but my biggest concerns are aesthetics and the smell of cooked food... maybe a large flush-ceiling mount is not all that bad, and I could just keep it going for a bit longer.

Yes I am stubborn :) and I kind of hate those hoods that flare out at the bottom. I will continue investigating using @gigelus2k13 formula though!

A downdraft hood - which might be the worst idea ever and a nightmare to install, and negatively impact a gas burner, will, but for a tripping accident, make it impossible for your husband to bang his head.

Thanks everyone for the advice and suggestions!

Soo..... it looks like we might be changing to a smaller (30" induction) cooktop instead of the monster Wolf stove we have since each burner on the current stove is 26000 BTUs.

I am now exploring downdraft hoods and we are strongly leaning towards an induction stove/downdraft hood situation.

I will update here what we end up deciding :)