Your wife is right, whatever you trying to come up there with is ugly.

The hood vent clearance should be anywhere 24-30".... 40" is way too high.

you can get a 34" range hood insert and have a custom Range Hood Cover built for it.

@GN Builders do you have any suggestion of range hood cover design that would look nice in this kitchen, while letting me to maintain the capture area I need for the cooking I do? (ie. it will have to stick out 30" form the wall while the upper cabinet is only 12" from the wall.)

You are overthinking it. Hoods don't collect air passively, they suck the air up. If you feel you do an excessive amount of frying get a more powerful hood (and don't forget makeup air) A good 30" hood mounted 30" above the cooktop will work great and not cause you to get divorced. You could get a decorative 'chimney' style model or get an insert and build it into a custom cab.

Many people on this forum have Bluestar ranges. I’ve never once seen a setup like yours, where the vent hood sticks out so far beyond the range, and is Installed as high as your proposed unit. They have powerful hoods, 6” wider than the range, with high CFMs, which perform efficiently.

Look at Vent A Hood. Their hoods are custom made, powerful, easy to clean, and even on high, are quiet enough to hold a conversation. You won’t find them at big box stores. Nor will they be inexpensive. Look for an independent appliance dealer, where the staff is well trained, and can answer all questions knowledgeably.

Heres ours, not above a Bluestar...though, it could be. Click to enlarge.

We have a 1200cfm 27" deep Wolf Pro hood with warming lights over a 48" open burner Capital range top that is pulled a couple of inches away from the wall. My husband is 6.5" so the hood is mounted 40" above the countertop. He has never bumped his head and at 5'3" I can easily reach the controls on the front edge. We use the warming lights every day for one thing or another. The Wolf badge was packaged separately so we didn't put it on. It works well for us.

https://www.subzero-wolf.com/wolf/range-hood/30-inch-pro-wall-hood-27-inch-depth

@darbuka thank you for your suggestion. This is the exact reason I am at a loss now because I cannot find any other set up online that gives the same coverage.

The reason I need it stick out that much is because I cook with a 14 or 16 inch wok frequently on my stove. Even with a 36 inch wide 24 inch deep hood (which is what I have in my current house) can barely capture 50% of the flue gas when I sear meat on the pre-heated wok, as you can see the dimension in the picture below taken with just the 14" wok.

That's why in the new kitchen I want to make sure the Hood aperture be able to at least cover the entire area of the wok plus a bit.

p.s. On the side node, what griddle plate do you have on your rangetop? I don't think I have seen that design before and it looks like something I would want!

These stick out and look good

I think the height is what is throwing off your design.

That griddle has been in my husband‘s family for over 50 years. Believe it or not, it was made by GE, back when they were known for quality.

Up the CFM to up the capture I very often design 30” gas ranges with a 30” hood but with more CFM and also hung at the proper height. IMO some things are just better already made. BTW I use vent-a-hood very often and I do not like hoods covered in the wood it gets gross and after some time it discolors and you really notice it in a white cabinet kitchen. BTW you can buy a griddle that spans 2 burners for $35 I have had mine for 40 yrs well seasoned and works perfectly.

@wilson853 Thank you for sharing your experience. Do you have a picture of the installation in your kitchen so we can have a look on how hood this size and design and installed at the height we want would look in real life?

@Katie B. Thanks for the recommendations. Unfortunately the bottom of the hood needs to clear my head while the retractable hood has no containment area for smoke. Our cooking involves a lot of high heat searing and stir fry so a flat bottom hood will not work for us.

@darbuka I will now start looking at vintage griddles on craigslist/kijiji! Cause I look at all double burner griddle available on the market and none has the design I want (thick carbon steel bottom, with raised side wall and grease trap)

@Patricia Colwell Consulting Thank you for your suggestion. I live in Canada so I want to minimize the CFM as much as I can by adapting other design changes cause in winter setting up and running a high flow heated MUA is beyond our current plan at the moment. The remote blower I am selecting right now runs at max 800 CFM, with just a 1 foot long 8" duct directly at the back of the hood, which is sufficient if I have the capture I want.

As the OP has noted, large wok cooking on front burners will lead to an expanding plume that can miss the hood entry aperture area. The only hope for a less deep hood is to make the entire area from cooktop to hood an effective entry area. This is only reasonable with a wall hood, and requires cabinets and/or side skirts and additional CFM, although perhaps not much more than the 30-inch depth hood would require.

Large 30-inch hood requirement: [(30 x 34)/144] x 90 = 640 CFM actual; ~ 1000 CFM rated blower, assuming reasonable MUA performance and typical blower fan curves and baffle pressure losses.

With this airflow moving across the room and into the hood, side and back restrictions will tend to increase the velocity of the approaching air between the front edge of the cooktop and the front edge of the hood. This may be enough to deflect the wok plume somewhat into the hood entry aperture because the transverse velocity will be rising as the wok plume is expanding. There are too many variables to evaluate this without a computational fluid dynamics simulation, but the experience of others with similar configurations may be sufficient.

I won't delve into spousal aesthetics.

@Katie B. Thanks for the pictures! I think I found the biggest problem with doing a deep hood in my kitchen... the ceiling is not high enough to make it look nice when squared off.....

@wilson853 That looks beautiful! I think that extra foot of ceiling with the crown moulding definitely reduce the contrast of hood sticking out more than usual. Let me see what I can do with crown moulding with just 8.5' ceiling.....

@kaseki Thanks for chiming in! your extensive thread discussion on hood calculation and design was definitely the inspiration for me on how to take on this challenge. I like your idea on airflow moving across room to help draw the plume into the hood. I will definitely have to think about if I can design that flow for the kitchen. Regarding loss, at 640 CFM actual, there is a loss of 0.007 inH2O from the duct, 0.05 negative pressure in house and 0.23 inH2O from the filter (sources references below). Correcting the fan curve from Broan 332 blower for 800 CFM rated, I can get 750 CFM actual at this calculated loss, so I still have some margin to for the flow rate using the blower I plan on using.

Calculation References:

Pipe head loss https://www.engineeringtoolbox.com/duct-friction-pressure-loss-d_444.html

Baffle filter loss https://www.safid.com/pdf/Kitchen%20Hoods.pdf

Broan fan curve http://www.broan.ca/common/productDigitalAssethandler.ashx?id=06ce438e-6732-4a1c-9c68-b3eb1902e9c7

So taking these information, I kind of tweaked the design to something like this. As this is more complicated, I cannot really overlay it on the current kitchen using paint. This is drawn using CATIA (accurate model but crap texture and shading)

With the internal cross-section looking like this

What are your thoughts? :)

Do you have any combustion appliances using gas that have relatively cool stack temperatures?

Do you want to run a fireplace when using this hood?

In any case, your pressure loss calculation doesn't yet include the make-up air pressure loss. Assume first a passive MUA. That is, assume an MUA system in which there is no blower. Then the pressure loss will comprise, mainly, duct losses (small), air filter losses (significant unless you like birds and bugs), and outlet diffuser pressure losses (modest, probably). If a water to air heat exchanger is used instead of a set of hanging electrical coils, some added pressure loss will be needed.

So, for initial analysis, estimate a duct run and find its pressure loss, find an example diffuser from Hart & Cooley and look at its pressure loss data, assume a filter caddy for some size folded air filter (e.g., 24 x 24 inch) such as a 3M Filtrite (1, 2, 3, or 4 inch pleat) and data for it, and that the flow rate is the same as the hood. There may also be pressure loss in the device connecting the MUA duct to the outside. For this case we want to assume that the house is otherwise perfectly tight except for the MUA. When the resulting pressure loss is added to those you have calculated, you may find that the total pressure loss moves you much closer to the needed CFM on the fan curve.

It will also add to the negative house pressure, which matters depending on any combustion appliances and their type.

Catia still exists! I thought by now Parametric Technology and Autodesk would have eaten their lunch. Anyway, can you do a solids view from underneath?

@kaseki No to both.

I haven't thought too much about the loss due to make up air. The house is 5 decades old so it is definitely not as tight as new build. As of the calculation right now, I have room to loss another 0.2 inH2O for the blower to meet the actual CFM requirement. And since I think the interior volume of the house is also quite large (3000 sqft two storey home), I think the pressure drop inside the house when the hood turns on should not be too crazy.

Actually CATIA is still widely used in the Aerospace industry I am in. I believe it is still used a bit in Automotive as well. It is just not very suitable for hobbyist and or small-medium business that doesnt require super complex geometry and assembly, as the license for CATIA is one of the highest out there. Right now my solid is literally a .... Solid chunk, as I want to get the exterior shape approved by DW before I spend time to model the interior detail for creating the manufacturing drawing. That second sketch is just a sketch for me to know how I will place the internals.

Pressure drop when the hood turns on is a mere transient, although dynamically relevant. Larger hood motors take several seconds to spin up, so any dynamic effects tend to be spread out, pulse wise. The steady-state condition is of more interest. Without appliances needing inside to outside pressure within 0.03 inches, w.c., then the safety issue is taken care of. However, one really doesn't want to depend on house wall/seam/door frame/etc. leakage as a way of supplying the hood. House leakage can put humidity into walls and pull fiberglass dust out of walls.

A passive MUA might be only 0.2 inches in pressure loss, in which case the house will be at -0.2 inches. It was unclear from your analysis above where the 0.05 inches for house pressure loss came from, but I am reasonably confident that an open window with a standard mesh screen would have a higher pressure loss at 640 CFM. A large leaky house might only lose 0.05 inches, but again this may have a significant through-the-wall-seams flow component.

Also, if heated MUA is needed, it is best to heat a specific duct flow with an auxiliary heater. House furnaces are not intended to heat high air flow rates at cold temperatures, but only small leakages and conductive/convective cooling through the walls, attic, and basement. One can live with a cold draft, of course, but in some municipalities, not only is MUA required, but also heated MUA.

@strikeraj I think your aesthetic issue is more that your DW is accustomed to seeing a traditional hood appearance. The design you have actually looks more like the cabinetry and less conspicuous than the original vent hood if I were someone from another planet arriving in your kitchen for the first time having no other reference as to hoods. At some point she has to be grateful to have a husband who cooks so much! This is said after spending a hot, messy afternoon grilling steaks outside which is one of my least favorite things to do. So, getting indoor cooking setup where you can conveniently sear meat and do heavy cooking is a magnificent thing. Whatever you do, consider putting the wok on a back burner for extra extraction. I disagree with an above poster who said hoods are not "passive." In the function of "capture," they definitely are. Effluent can outpace the blower, and adequate capture area is needed. @kaseki has a Wolf hood in his own home, and his many posts led me to a Wolf as well for a number reasons including proper shape. I bought mine as a used display model at a showroom and saved some money that way. You might also check out Monogram pro hoods. Between those two brands, you might find something already suited to your needs that looks more like a traditional hood that your DW is accustomed to seeing. It would be better for the hood to be lower, but your vision safety and overall head safety are utmost of importance, so do what you need to do to keep from hitting your head on anything.

As extensively as you plan to use the hood, I'd look into Make-Up Air systems unless you can open a window when you're using the blower on high. The rated cfm won't perform at that level without MUA or the equivalent fresh air from a window.

Hood height: In planning for a hood height that doesn't contact the head, one can draw a side view of the cooking area with a stick-figure cook. Allow the stick figure to bend at the waist (or however one prefers to bend). The bend radius at the head will lower the head when it passes under the hood, if the hood doesn't extend out to the cook's position. This can save a tad of hood height. Also the cook will quickly learn to duck after a few contacts from a too-low hood.

In my view, one definitely doesn't want a hood low enough to block site lines to the pots and pans on back burners, so there is a trade between hood front-to-back depth and height above the cooking surface, independent of the need for capture area overlap. This too can be evaluated with a side view drawing.

Another factor with a hood that extends toward the cook but just misses the cook when leaning in is use of halogen lights forcing the cook to wear a hat. In such cases, replacement with LED based lamps is helpful, where possible.

@kaseki @Aglitter Thanks for the replies! I have done a little more research today so I am going to share what I found and my thought process. (that 0.05 number I just pulled out of no where so here I am digging deeper into this rabbit hole LOL).

First of all, the tightness of the house. I consulted my home inspector that inspected the house. He told me that house that age (3 decades old) would just be a moderately tight house, which means it would have a leakage rate at more than 1500 CFM50 up to 3000 CFM50, and 50 pascal equals to 0.2 inH2O. So lets assume my house is on the tight side of the spectrum, if my range hood is pulling 700CFM actual, it will conservatively generate a vacuum of 0.1 inH2O. Therefore, concern about pulling in moisture/fiber aside, the blower should be adequate to draw at least 640CFM even if all windows and doors are closed with NO MUA.

Now onto concern about MUA and condition.

IRC does not apply in my local area and my local code has no MUA requirement for residential. So legally, I am not hooked on anything.

I plan on running the hood at full power only when I am searing/stir frying/broiling, so probably I will be running at 20 min MAX each period. Other times if I am just simmering/boiling/baking, it will be run at less than 400 CFM so I guess the rule of thumb is that at 400CFM it should not cause too much trouble as most codes In terms of MUA, during warmer humid months (MAY-OCT) I plan on just cracking the kitchen windows/patio door in breakfast area when I am running full motor power.

During the cold/dry winter months is where it becomes tricky. I plan on relying on the leakage and the 100CFM that can be compensated by the HRV system. In this case, pulling in humidity is not a concern so I am not at high risk of having mold growing in structures. I am fully aware that this is not the ideal situation, as you won't know what the leaked in air brings in, but for the 20 minutes a day of full power use, I am ready to accept that. Currently we are living in a 60 year old house that is even worse.

As to loading of the furnace, this is not really a constant flow. At 700CFM running 20 min, I am bringing in extra 14000 Cu Ft of air at outdoor temp (assuming 0F). To heat that air to room temperature (assuming 70F), it takes 12,600 BTU, which is around 38,000 BTU/hr. The furnace is capable of 80,000 BTU/hr at 94% efficiency, so this accounts for less than 50% fluctuation which I believe it can handle for short duration.

With the HRV and filtration at the air handler, I think we will settle for the compromise for not spending extra $5-$10K on a properly sized, built and conditioned MUA system.

As of hood height, since I am planning to extend it to 30" deep, I just want to keep it safe and have enough margin (I am 6' and my father in law is 6'2"). So right now I am planning to have the front edge at 40" above stove top. And yes, I will be installing GU10 LED light in this hood :)

Here is my latest rendering using Microsoft Paint (took me almost 2 hours....)

14000 BTU. 14k BTU/20 min = 42k BTUh. Doable it would seem. Otherwise, nice analysis.

@kaseki ah crap... I need to retake elementary math lol... Missed everything by 10 times....

Thanks for picking up that mistake!

I have edited the post above to correct the calculation.

Sounds like you have more than adequately covered your bases. Is DW agreeable to the new look?

@Aglitter trying to convince her.... She is still having a hard time to accept the fact that the bulkhead needs to be removed at that section.... LOL

Out of curiosity, what would the lower edge of your planned hood be up from the finished floor if you mounted below the bulkhead? You only need 72 inches not to hit your head, and 74" for your father-in-law. You don't need all of that 40" mounting height to get that unless the ceiling height is quite low.

@strikeraj Adding to the above, I imagine we could find you a low-profile hood that would work well and still allow your DW to keep her soffit. If you want, post the ceiling height above finished floor, the soffit height, and the height of to the top of your range not including grates.

@Aglitter The ceiling height is about 94 inches, so with right now the front edge of the hood is sitting at 74 inches from the ground.

The reason I would not consider a low-profile hood is that none of those has the filter sitting at a proper angle (45 degree or more) in order for the grease to drain properly into the cup.

Commercial hoods require by code (NFPA 96 I think) 45 degrees or more slope, a cup, and also a sprinkler head. Residential hoods don't have these requirements. Residential pro type hoods usually have a more shallow angle and provide a very modest ability at the low end of the baffles to collect grease. Residential hoods also typically take weeks to accumulate as much grease as a commercial kitchen might accumulate in a day. So, a lesser slope than 45 degrees will usually be adequate; the grease that moves to the low end will likely end up in a shallow tray that the baffles sit in. If you really fill the trays faster than it takes for grease hardening, a drip will certainly provide warning of a need for cleaning.

On the other hand, hoods characterized as low profile usually have no baffle angle, requiring more frequent cleaning. (Any grease pooling will be into the under baffle of each pair.)

@kaseki Agreed. Another big problem with low profile hood is that it provides a very shallow containment volume for sudden burst of plumes due to searing/stir fry. As was discussed in the other thread, we are sizing the motor for an average flow. If the capture volume is not sufficiently large, the sudden burst will overfill the volume very quickly and start leaking out of the hood.

I guess I meant "lower" profile than a traditional pro hood but still with adequate containment area. However, your ceiling height is lower than even a typical 8 feet, so you don't have much room to work with there. If you have funds, you can remove the soffit entirely and double-stack cabinets above it. Many people choose to put glass-fronted cabinetry in the double stack area. Many times that soffit is just a way to save on cabinetry to ceiling and doesn't serve much purpose. Other times it could contain vent ducts or electrical wiring, so you have to be careful.

If you wanted to tweak the measurements to perfection, you could do a custom hood. I have ordered a sink from Havens Metal in Florida, and those people are true craftsmen. They do a lot of custom hood work, and you can get products in both copper and 316 stainless steel. They have a textured stainless finish called Prestige that is amazing. Here is a photo of a custom hood they have done and a link to more pictures:

https://www.havensmetal.com/pages/havens-metal-shop

@Aglitter Thanks for your reply.

I think there is some confusion of terms here so I will refer to the term used in this thread https://www.houzz.com/discussions/5161173/hood-faq . There are two main component of passive hood design: hood aperture and containment area. Hood aperture is how wide and deep the hood is, and if it is covering the area of the plume rise (general rule of thumb of pan area +10 deg). Containment area also needs to consider the height of the empty space in the hood before going through the baffle filter, which is meant to temporarily contain the burst of effluent (eg. adding meat to a hot pan for searing) before the fan catches up and pull the smoke out.

A low profile hood can be big enough to have a good hood aperture, but it will never have enough containment area due to the physical constraint. Containment area can ONLY be increased by increasing the empty volume in the hood before the filter.

It is a very good suggesting to convert the soffit to cabinet and I believe it would be gorgeous. It is just not top on the priority list so we don't want to increase the budget for it if we have another solution.

And yes, we are planning to do a custom fabrication as we have an unusual opening there to begin with (34" wide opening between top cabinets). I am just having trouble coming up with the design that can both satisfy the functional requirement of a hood while keeping it aesthetically pleasing to DW lol

@kaseki @wilson853 Since both of you have the Wolf hood, do you mind if I ask you a few questions?

1. Do you think it offers enough containment area to hold a burst of smoke from steak searing?

2. Would you mind to share a picture looking from below the hood on an angle from the side? I wan to see how much empty space the Wolf design has and how it relates to the containment performance you observed.

Thanks in advance!

First, let me note that I haven't yet gotten to my promised effort and built a self-consistent FAQ. The space below the baffles should be called capture volume, while the space above the baffles is the containment volume, because it is the one-way passage of fumes past the baffles that defines containment. Capture is done by the hood entry aperture, but can fail if plume components reflect back out. Components that do not reflect out are contained, but this is only a sure thing once they pass the baffles. [Heh: not to be a pedant or anything.]

Here is a view of my hood. Note that this is the largest Wolf Pro Island hood, but was built by Independent back ca. 2008 and may differ in small details from the units now being sold by, and I understand built by, Wolf. It is sufficient for wok cooking on my Cooktek induction wok hob, but I wouldn't call the transient plumes large relative to those possible from a 100k BTUh asian kitchen wok burner. Steak searing is usually not so sudden in effect, so our cooking might not be a good comparison. However, due to its size and air flow (more than 90 ft/min on high) the entire length can act as capture volume, whereas a less wide unit with the same configuration will have less volume.

Click to enlarge.

Steaks are done outside, but we occasionally use a wok and do other high heat cooking. We took the baffles out on Saturday and they were greasy. The adjacent cabinets are 15" deep so are pulled one foot away from the hood. Amazingly they stay clean as does the glass.

@kaseki @wilson853 Thanks for the pictures! It seems the new Wolf design has quite a nice capture volume! I am now trying to play with a smaller filter design to see if I can somehow make a low profile hood out of it.... with still some capture volume and some containment volume, as I dont need to have the blower inside...

@strikeraj My Wolf hood isn't installed yet and is wrapped in bubble wrap, but I was able to reach in and measure the height at the peak underneath, and it is about 9" for the pyramid style that is 24" deep front-to-back. Mine only has baffles on the back of the peak. It was one of the deeper hoods that I was able to find just shopping around and viewing residential hoods locally in my Dallas, Texas, area. Many so-called "pro" hoods have shallower angles than the Wolf. Also, brands like BlueStar can vary in baffle angle from hood to hood within the same brand. We're installing the blower inside the hood, so yes, you might have some design options to make your baffles angle up higher since you'll have an exterior blower.

For your purposes, I'd really encourage you to check with CaptiveAire. It's a hood supplier that generally sells to restaurants, but it might meet your needs for heavy-duty extraction and deep baffle angles: https://www.captiveaire.com/catalog/showCatalogList.asp?cattypeid=64

Also, the heaviest cooking will allow some grease to coat your ventilation ducts regardless of how good your hood and baffles operate. You might give some thought to searing steaks outdoors as @wilson853 mentioned. I've recently run across a new concept in searing and slow cooking over charcoal from the Slow 'N Sear company (SNS). They combine the concept of a Kamado with multi-zone cooking for great effectiveness in both searing at high temperatures and slow cooking at low temperatures. Here's the link to the website, and you can find more reviews and demos on YouTube: https://snsgrills.com/collections/grills/products/deluxe-kamado

The containment volume, as I have defined it, serves two purposes. One is to provide a transition from the baffle area to the duct area. There are few hoods that make any real attempt to provide a smooth transition.

The second is to equalize the flow through the baffles. To do this with very narrow hood shapes, such as the OP photo, the baffles have to be very restrictive, or replaced by mesh filters.

Transient containment volume in this space is not really important. What is happening is that whatever gets past the baffles is initially speeding along near 180 ft/min (locally, 90 ft/min average), and has to quickly speed up to 1000 - 2000 ft/min approaching the duct. The baffles, in other words, are a choke point, and flow beyond them is not significantly affected by how much cooking plume is entrained in the air.

In principle, one could overwhelm a hood by having the volumetric flow rate of all plumes exceed the hood CFM. I suppose this is possible by wok cooking on six burners at once. In such cases the entire hood should be larger and so should the resulting volumetric flow rate.

@Aglitter

Thanks for the measurement and sharing your experience from comparing the different hoods. I have looked at Captiveaire but after comparing cost, my local builder for restaurant hoods have better pricing for the basic features I need. Captiveaire definitely has a lot of nice and useful features, if you are willing to pay for (eg. they have filter that can capture 70-80% oil, while regular baffle filter captures less than 50%. But the down side is the huge jump in resistance, so you need a much more powerful blower for it to work).

I have been tempting to actually build an outdoor kitchen for my cooking (commercial wok burner!!!!!) but it is just not very practical as Canada is winter half the year..... And what beats the convenience of searing, basting and finishing steak all at one spot while cooking other garnish LOL. I will still have an outdoor BBQ for the smoking and party grilling though.

@kaseki I totally missed thinking about the transition between slow flow to the high speed duct flow! I looked a bit and I think I will put something like this at the transition of duct to the containment volume

https://www.ecmdi.com/8-spiral-takeoff-with-gasket-82590

Now with all these consideration.... I am thinking may be I should just spend a bit of time and run some CFD models.... even though the thought of modelling the baffle filter is putting me off LOL

Also Re: WOK cooking, a single WOK cooking can overwhelm 800 CFM for sure when I am getting the vaporized oil to light for the "wok hei", on my modified bluestar burner LOL

Logarithmic conical would be best (tuba shaped). Tangent at both with constant radius might be good. But really, no one else in the residential hood game is bothering, so a fraction of an inch of pressure loss won't likely be missed. Baffles dominate most circumstances assuming adequate MUA.

The place most important to CFD analyze if you are going to have to use someone else's baffles is the air flow over the counter, into the hood aperture, and thence to the baffles, reflecting off surfaces as may occur, given hot sources and gas flames at the counter height. Treat the baffles as slots for this exercise. Cooking plumes should be at the temperature of the vaporization of hot oil (unless you want to do flaming oil) supplemented by the annular gas combustion products at their combustion temperature. Obviously, these are cooling as they rise. You should see 1 to 1.2 m/s velocity a meter above the cooktop. (A guess based on the Finnish measurements study.)

The question to be resolved is spillage vs. CFM.

@kaseki and @strikeraj Could go into the hood manufacturing business together and be a smashing success, I feel sure. :-)

Hi - I don’t have any suggestions for you, but wanted to let you know that I loved your use of the word “fugly” in your post. Happy to have a little chuckle to myself today.

Hi striker. Changing your backsplash isn’t a major remodel. Let us know if you’re interested in choosing a new one. Good luck with the vent hood - BlueStar makes them too. Choose one of theirs.

@kaseki to actually optimize transition you actually need a custom blend from the cylindrical tube to the rectangular area, but I am not ready to fork out money for that lol, as it is not a shape that normal metal fabricator can make to exact curvature. That's why I am just looking at an adapter that is commercially available that can get 70%-80% of the result of a fully optimized one.

Thanks for the idea of using slots as baffles to simplify the geometry. I think it actually may serve our purpose in finding spillage vs CFM for comparing different design! Will see if I can find time to set up this model. Haven't set up a CFD model since almost 10 years ago lol

@Aglitter no this is not a business I am getting into XD too much work for too small of a market, that actually cares about the performance of a range hood at home. I would rather share and develop this knowledge for this small community that wants to make a difference in our house

@Val B Glad that brings a smile to someone at times like this :) I feel proud!

@eam44 Thanks for the recommendation. To fit the commercially available hood that I want in this kitchen requires remodelling the whole top cabinet, as the current opening is a very odd 34 3/4".......

"To fit the commercially available hood that I want in this kitchen requires remodeling the whole top cabinet, as the current opening is a very odd 34 3/4"......."

A hood insert for a 36-inch cabinet might fit this space; you would just have to put a cabinet front on it.

@kaseki Thanks for the suggestion. I have actually considered that before but it also costs more than just getting a custom built hood, as most hood insert are pretty bad in performance and functional design.....

You're right that the market for exceptional hoods seems rather small. It's not uncommon for people to post on Houzz something to the effect of wanting a hood for under $1,000 USD that is "effective." When contributors explain what is effective in regard to shape and features and suggest raising the budget, then the original poster responds that they found a great deal for a few hundred dollars and that will have to suffice!

My comment above refers more to the precision with which the two of you have calculated the physics necessary to maximize ventilation, something that even the research and development teams at major hood manufacturers have apparently not done based on some of the designs available out there, at least for the residential market. I think educating the public might go a long way toward increasing the market for better hoods, like having reviews on popular cooking shows or talk shows about it.