Thanks @Patricia Colwell Consulting. I appreciate the advice on VH. After some consideration, I've decided that VH is probably not the product for me as I can't increase the CFM without going even wider on the hood. It's too bad they don't use 400 CFM blowers instead of 300. Since I have the elbow, I'm definitely going with something more powerful.

Thanks @clinresga! I'll definitely look into those threads (and the scotch) :) A Modern Aire hood liner with a remote Fantech blower sounds like the perfect setup, but I don't think I'm going quite that fancy. Instead, I'm leaning towards Victory Range Hoods Twister Max (1150 CFM with 10" ducting, baffles). It's a good value and appears to be built well enough. Also, they have pretty solid reviews on Google! My wife and I also have decided to go with an induction stove, which should cut down on some of the combustion pollutants that come with gas ranges.

Thanks, @clinresga for popping up and piping up, but you failed to specify which scotch. ;)

On the subject of filters (exclusive of squirrel-cage extraction blowers used by VaH): At the flow velocities needed for good extraction with baffles, true baffles are needed. These are alternatively 'U' shaped and inverted 'U' shaped. When a mesh filter is involved, the centrifugal extraction process achieved by a true baffle is defeated, and one mainly has a partially blocked mesh filter. Mesh filters can be useful at achieving grease collection via impingement when flow velocities are low, but such velocities cannot achieve containment when subject to hot oil cooking such as searing meat or wok cooking. For these, air flow at the hood entry aperture should be of the order of 90 ft/min, leading to ~ 180 ft/min at the baffle slots entraining the cooking plume(s).. Induction hot oil cooking needs perhaps modestly lower flow rates due to lacking the hot combustion effluent from gas heating.

So, the range of achievable CFM needed is somewhere between the hood entry aperture area (sq. ft.) times 60 ft/min and times 90 ft/min. The blower that can achieve this when baffles or other filters are blocking the air flow, and MUA is imperfect is about 1.5X these values.

MUA is still needed. No air leaves the kitchen up the cooktop hood that doesn't enter the kitchen. And it has to enter with low pressure difference between outside and inside. How low depends on presence or not of combustion appliances and their requirements, and this is a topic addressed in other threads here.

Your information on filters is very helpful, @kaseki. I'm sure I want baffles and not mesh. Regarding MUA, my builder shared that the cost is $650. However, if I go over 900 CFMs, the cost goes up to $1850! My workaround: Victory is going to cap the CFMs for their 1150 CFM unit to 900 CFMs. This should allow me to get away with the more basic MUA system. I am not sure if the MUA will be integrated into my HVAC or if it will be ducting with a motorized damper. Does this make a big difference?

Also, not sure if I should start a new thread, but here it goes: Does anyone know if EMFs generated by an induction stove are dangerous (cancer-causing) to children or adults? This is a key concern of ours. I've read on fda.gov and cancer.org that microwave radiation (similar to induction stoves) does not cause cancer, unless there is a major radiation leak.

Microwave radiation is almost as far away as one can get from induction cooktop radiation. Microwave oven frequency is at 2,450,000,000 Hz, whereas induction cooktops operate near 40,000 Hz, much lower than the AM radio band. Due to their long wavelength (speed of light divided by frequency), induction frequencies do not propagate from the tiny fraction of a wavelength induction coils. Rather, somewhat like magnets, their fields extend to distances commensurate with their coil dimensions -- just above the cooktop in a half toroidal shape (think donut sliced horizontally). These fields only react with susceptible metals, and not with human tissue.

EMF, thus, is more of a risk to closely positioned electronic health aids, and not directly to human organs.

As I may have noted, and documented in other threads, the pressure loss allowed for a given house depends on presence or not of combustion appliances in proportion to their back-draft sensitivity and the presence or not of local combustion appliance MUA.

I can't comment on whether a particular HVAC system will be affected by being used for MUA. Please read MUA threads here to absorb perspective on how the MUA should be introduced to the kitchen, and when passive vs. active MUA are appropriate.

That's great to hear about induction v microwaves! I will read over some MUA threads in time for my conversation with the HVAC engineer tomorrow. Regarding induction, I'm thinking I won't go with Frigidaire. They have horrible customer service! Unable to provide standard wattages of elements without power boost. Unable to provide maximum output of the induction stove (after waiting 30 minutes on hold, she hung up on me after this question). Edit: I called back and another person was more helpful. They gave me the tech support number so hopefully I can get some answers.

One note, my builder told me that the difference between a 40A and 50A stove for wiring purposes is that they each have the same wiring and outlet. Only the breaker changes. Is this correct?

Thanks very very much!

"you failed to specify which scotch. ;)"

I'll jump in on this one :-) Auchentoshan (any), Lagavulin 16, Oban (any), Balvanie Double Wood are my current favorites. All but Oban w/ a sprinkle of water. Quite frankly I think about 85% of Single Malts made in Scotland are good - not sure if that's because they're so good or I'm a bad judge of good Scotch.

"which should cut down on some of the combustion pollutants that come with gas ranges."

Yes, but a lot of VOCs, PM and Carcinogens from cooking itself.

Any exhaust of 600 CFM or over should always have Active MUA with a blower that matches the CFM of the exhaust. This is now code in many states. A newer and better sealed house then anything 400 CFM or over should have Active. Passive is OK for less than 400 CFM in a not so well sealed house (higher than maybe 2.0 ACH50).

Ask your local radiologist if they'd put an induction in their home. :-)

There are a lot of pros and cons to induction and gas. There are some cooking techniques that cannot be done on induction and some that are more difficult. OTOH, good induction with a probe is great for keeping something at a constant temp. The potential health risks aside the right answer will be different for everyone depending on what they want to be able to do with it. We have both (https://bamasotan.us/the-kitchen/)

Beautiful kitchen, @opaone. Can't say I know any of those scotches but I'd love to give them a try!

Regarding the hood, thanks for explaining the difference between passive and active MUA requirements. I'll be sure to bring up that I need active MUA w/ blower with my HVAC person.

Thank you!

If you're new to Sotch... Maybe start w/ a Balvenie Carribean Casket, then an Auchentoshan 12, then an Ardbeg 10. This will give you a bit of an intro tour. Scotch is always good w/ a splash of room temp water IMO. I'll frequently take a sip neat and then add the water for sipping. Never any ice.

@opaone: I have some of those; I'll have to look for the Auchentoshan.

Even ancient diathermy machines operated at nearly two orders of magnitude higher frequency. If you know of any documentation on interaction of weak low frequency radiation with tissue, I'd be interested. (A submarine communication antenna farm might be a different matter.) Of practical relevance, with the hob covered by an inductive pan base, there will be very little energy available for interaction with flesh, even when one puts some close to the hob edge. I once measured my previous Kenmore (also an Electrolux clone) with an oscilloscope and probe with a wire loop, and I had to get it very close to get above the baseline noise level.

@Joe: "One note, my builder told me that the difference between a 40A and 50A stove for wiring purposes is that they each have the same wiring and outlet. Only the breaker changes. Is this correct?" In my case, the induction cooktop (36-inch Frigidaire Gallery) is hard wired, so the term outlet as usually used doesn't apply. I used Greaves fittings in the junction box that the cooktop flex connects to. (https://www.greaves-usa.com/wp-content/uploads/2020/03/60.pdf) For actual plugs and receptacles, find an image of NEMA connectors to see which ones could be used. [Example: http://extranet.garland-group.com/document_catalog/Document%20Catalog%20Files/nema%20Plug%20Guide.pdf] Caution: Parts connecting to high temperature conductors such as are often used for kitchen cooking appliances must be rated to at least the same temperature.

For wiring, I used 6 AWG conductors in my wireways and conduits from breakers to the junction box. Note that while certain sizes of conductors are associated with particular maximum currents, the allowable performance is complicated by temperature and distance considerations. Your electrician can expound further.

For the cooktop, any combination of full power settings with no more than 3 power boosts at once (as defined by the generator schema of two pairs and one singleton hob) should be within the design capability. I've never had to do this in real cooking.

@kaseki, appreciate the info. I think I will have them upgrade the wiring to either 6 AWG aluminum or 8 AWG copper. So, in the event I get a higher kW stove in the future, I should be able to basically swap the breakers.

For anyone interested, I'm rethinking Frigidaire. I called customer service, they forwarded me to tech, and then tech told me that not only can I not have any information until AFTER I buy the product, but that the wattages of their elements are "proprietary information." They quickly shared that if it's not in the manual, then Frigidaire does not want customers to know about it. No thank you!

Regarding MUA, I will be getting a motorized MUA system that turns on/off with the range hood (but does not modulate, so it won't exactly match the fan speed). I'm okay with the inexpensive compromise. My HVAC person also is running the ventilation for the gas dryer and gas furnace to the roof (instead of the back patio area) at no charge. The plumber is charging $450 to run the water heater venting to the roof. All in all, not a bad price to improve outdoor air quality and get those fumes away from my windows and patio

Use 6 AWG copper and be done with it.

And finally I am reaching the very last of my selection decisions for the home! Unfortunately, I am stuck.

1) I can vent the range hood 22' (equivalency with 2 bends and a wall cap and dampers) out to an exterior kitchen wall.

2) I can vent the range hood 45' (equivalency with 3 bends, roof cap and dampers) out through the roof.

My concern is air quality. The exterior wall vent exhaust will be placed 2' above my kitchen window and 3' to the right of it (the exhaust is located between the first and second floor-- please see photo). And in regards to the second floor, there is a bedroom directly above the vent exhaust. The vent exhaust will be about 2 ft below the bedroom window and 4 feet to the right of the window. Should I be concerned about smoke leaking in through an open window and simply choose to vent through the roof (accepting the diminished efficiency of the hood)? How much CFM loss am I looking at? THANKS so very much.

@Joe I had this same concern when the HVAC guy for our new build vented the range hood out the porch roof a few feet from a bedroom window. (I could have shot him but that's another story). There are multiple issues with his installation but infiltration of kitchen fumes into the bedroom in not one of them, fortunately, though it is unsightly. We have large Andersen 400 series casement windows in that room and the walls inside are foamed with Hardie exterior siding. There have never been any discernible odors, fumes or noise from the vent. Because we rarely have spring/fall weather anymore in the mid-Atlantic, the windows are rarely open. YMMV.

"(but does not modulate, so it won't exactly match the fan speed). I'm okay with the inexpensive compromise."

This is a little confusing as there is typically little to no cost difference to have the MUA blower CFM match that of the exhaust hood. This is a motorized blower and not just a motorized damper correct?

Electro Industries for instance is a simple all-in-one MUA. Put a sensor coil on the hot lead for the range hood, commission it (e.g., measure CFM of range hood on Hi-Med-Lo settings and then set MUA to those same CFM's, and it's done). I believe all fantech blowers are now variable speed and you just use an outboard controller with them.

Depending on your hood, the CFM's and how properly sealed your house is you want the MUA to match the range hood.

"How much CFM loss am I looking at?"

Depends on the fan curve of your blower. With some it would be minimal with some it'd be very substantial.

"My concern is air quality."

Again, this depends on a number of factors. If you're a typical American and keep windows closed and ignorantly think that your inadequate HVAC ventilation is keeping the air in your house healthy then it's likely not much of a problem. :-)

Otherwise I'd find some place to exhaust to that will not keep you from opening a window. No matter how good of grease extraction your hood has there will be a lot of gook and odor in what's exhausted. If it's really poor then you could also end up with some grease buildup on the windows.

Roof is generally better, but YMMV. Seriously, while the effluent from a wall cap is typically directed downwards, wind conditions can certainly move odor and grease particulates toward open windows, if present. The best approach is a roof mounted blower, with a silencer in the attic (if present). Of course, this depends on architecture for the duct path, where on the roof it can be mounted, what location the MUA might be taken from, inconvenience of servicing (roof slope, etc.).

Whether roof or wall, the blower has to be sized to address the pressure loss of the equivalent feet of duct (varies with air flow and duct diameter), the baffles (varies with airflow) and make-up air system pressure loss (particularly if passive, but perfect balance if active is improbable).

By sized I mean that the goal is for the actual flow rate to be the desired flow rate at the pressure loss corresponding to that flow rate. Wolf engineering can provide such curves for their products. Broan provides fan curves for their blowers, but I don't know whether they will supply pressure loss curves for their hoods). I anticipate that except for the quasi-custom makers such as Abbaka and Modernaire, such data would be hard to obtain.

Else, based on 90 CFM/sq. ft. of hood entry aperture to find the desired flow rate, multiply the desired flow rate by 1.5 as an estimate of the pressure loss effect and obtain a blower capable of that value in free air (where blower ratings are made).

@cheri127, Thanks for sharing your experience! Ideally, I'd like to keep windows open sometimes in spring and fall. That being said, I can just close them while I cook.

@kaseki, It's interesting that the effluent from the wall cap is typically directed downward. That sounds like it could flow right into my kitchen window! If I keep the exterior wall exhaust, I'll definitely use a box fan in the window if it's open and I have the range hood on. I probably cannot find it in my budget to go with a roof mount, silencer, etc.

Regarding the calculation, does this sound right: 24" depth x 36" width = 6 feet. Next, 6 feet is multiplied by 90 CFM/sq ft = 540 CFM. Last, 540 CFM x 1.5 = 810 CFM needed (in free air). Sounds like with a 900 CFM blower, I'll squeak by!

Does the 1.5 multiple cover pressure losses from 45' feet of ducting and elbows? I've read CFM losses are 3% for elbows and 3% for every 25' of straight ducting. If I have 3 elbows and a roof cap, that should equal 12% loss. Then an additional 3% loss due to the 25' additional feet of straight ducting. 900 CFM x .15 (efficiency loss) = 135 (765 CFMs left).

@opaone, you made some really good points, not all of which I have answers to. I'm not sure if the MUA system is a motorized damper or a motorized blower. I'm told the MUA costs $650, so I'm guessing it's a damper.. I will now have to clear this up with my builder and potentially agree to an upcharge for a motorized blower. Thank you very much for your attention to detail!

Also, I'm going to vent the range hood to the roof. Although it's more ducting and less efficiency than exterior wall venting, I believe 900 CFMs will still do the job. On the plus side, I'm guessing if I go with a motorized blower MUA kit then I'll be able to increase my CFMs to 1000 (I previously had to cap the 1000 CFM range hood at 900 due to the capacity of the MUA system).

Pressure losses increase with duct length, but also due to the pressure drop across the hood baffles [this may dominate], pressure losses dealing with transitions in the hood, whatever the roof cap is can be a factor, and the make-up air pressure loss adds to this. (Even screened windows have a pressure loss.) The overall pressure loss, which is a function of the actual flow achieved, can be modeled by a quasi parabolic curve on a pressure vs. flow chart. The blower fan curve can also be plotted, and the intersection tells one what CFM will actually occur. (See image.)

In the image, a system with the red pressure loss curve cuts the flow to about 50%. The lower green pressure loss curve cuts it to about 75%. I think a cut to 67% is a plausible condition for most, assuming a reasonable attempt at obtaining needed MUA.

The factor of 1.5 represents a 67% degradation of blower performance and in my view is no more of an approximation than asserting 90 ft/min is needed for a residential hood having roughly 50% baffle gap space dealing with 180 ft/min plumes. However, for most visiting here needing to know why their OTR microwave oven fan doesn't do much, making this 1.5X assumption in lieu of a full analysis will still yield a much superior ventilation result.

That makes a lot of sense regarding degradation and the fan curve. Now I see the importance of manufacturers publishing their fan curve!

Regarding MUA, I now understand the difference between a passive (damper) and active (blower) system. Considering the cost difference is around 2k, is it really WORTH going for the active make up air system (for a 900 CFM range hood)? This is a pretty big upgrade, which I'm happy to pay if there will otherwise be an air quality issue. However, my HVAC person shared that I will have no problems with backdrafting with a passive MUA system. I suppose I just don't want perfect to be the enemy of good. Thank you everyone. You have been incredibly helpful and thorough!

Back-drafting is the issue. If you have no combustion appliances, or combustion appliances with their own sealed MUA, and don't plan on operating a fireplace while running the hood, then some pressure drop will be tolerable. However, you must analyze the pressure loss of the passive MUA system and include that when evaluating the hood flow rate from the fan curve. For example, if the MUA is merely a large hole in a wall with a furnace filter, the filter pressure loss needs to be accounted for. (The data are out there.) A lot of pressure loss matched with a powerful hood blower will work, but then there will be air infiltration through the walls, and this has negatives for other reasons.

Don't forget that the MUA has to get to the kitchen somehow. If this is by ducting and a ceiling diffuser, say, then there are some pressure losses there. If via a wide open household from hole in the wall to kitchen, then just the filter is relevant. No filter avoids pressure losses, but then the environment needs to be really clean and insect free, perhaps like the South Pole.

"Considering the cost difference is around 2k, is it really WORTH going for the active make up air system (for a 900 CFM range hood)?"

See: https://bamasotan.us/range-exhaust-hood-faq/

"Above 400-600 CFM requires a mechanical make up air system with a blower that matches the blower for the kitchen exhaust – Active MUA"

I see the issue here. I believe I have sealed combustion appliances, though, and so backdrafting won't be a concern. I have noted NOT to run the gas fireplace at the same time as the hood! The way I'm looking at this, if the passive MUA does not match the range hood blower at a higher CFM exhaust level (say 600-900), won't I simply be able to open my kitchen window to get more fresh air in?

I would love to get a commercial brand like Accurex but I don't think it's in the cards. If the window solution works fine alongside the passive MUA, I think that's probably what I'll do.

@Joe, to be quite direct. Passive MUA w/ a 900 CFM exhaust system is exceptionally foolish. Both on your part and on the part of any HVAC contractor who'd knowingly allow it.

I appreciate your concern. Conceptually, I cannot understand how a MUA blower that lets in air is any more efficient than a MUA damper with a window open (at higher CFMs). It is still just a function of letting in enough air. The HVAC contractor does in part work off calculations..

I take it from your comment that the passive MUA system + window air is not sufficient for 900 CFMs (on max). How close am I getting then? Enough air for 600 CFMs? I hope I've explained this well.

If you normally have a number of windows open and it's rare that you ever close them then you'd likely be OK, otherwise you're taking a bit of a risk. One instance of having your gas fireplace on and someone turns the hood on without realizing could be detrimental to life happiness.

Air will always find the easiest route in to your house. So even with a properly sized passive duct the easiest route might still be down your chimney (even without a fire going it could suck in a lot of carcinogens) or through leaks in walls (really really bad if it's humid outside).

If your passive duct happens to be on the leeward side of your house it could act to negatively pressure your house (one of several reasons the damper is so important) or simply have too much negative pressure for your range exhaust blower to overcome and so prevents it from working as MUA.

Passive is OK at lower CFM's where the potential problems are relatively minimal but above about 400 you're starting to take risks.

Go back to my fan curve illustration. If the MUA is constricted, then one moves to the left where the pressure loss line intersects the fan curve line.* This reduces hood blower performance over performance with less pressure loss. Obviously (I hope) one can make up for this by adopting a more powerful hood blower, if feasible. Or one can augment the MUA path with a blower.

The issue of negative house pressure, and there will be a little even if all the windows are open when they have screens, is, from the safety point of view that I consider primary, a possible cause of combustion appliance back-drafting. If that is not an issue, then there is the question of what is coming in that is unfiltered and what is being entrained when house leakage is being deliberately or inadvertently utilized.

Ignoring code requirements that are based on blower rating and not actual flow, and possible conditions where opening the windows is not going to be tolerated by the occupants, I have no problem with outdoor air (at least where I live -- NH). There are places where outdoor air would advisably be filtered, and in these cases active MUA is needed because the pressure loss of the filtering is significant.

The image below is from a message another forum member provided. Some of these pressures are very low and a single screened window might reach them for a hood blower of reasonable size. There is another important factor: Even if one has ducted appliance exhaust and separate ducted appliance MUA, there is a negative pressure that the appliance will backdraft at due to its own lack of perfect sealing.

____

*For our purposes of hood blower performance, the pressure loss is the pressure drop going from the cooktop to the outside and thence back to the cooktop via whatever MUA path is being used. For back-draft issues, the negative pressure is measured from the area near of the appliance to the outside.

In spring and fall, windows will stay open. In summer and winter, probably two windows will stay open when we cook (providing we use the hood blower close to max). Regarding wind direction, the make up air is on the south side of the home and wind typically blows from the west. So not quite leeward.

Additionally, given that "air always finds the easiest route into the house", the open windows in the kitchen and dinette (these are the closest windows to the range hood) should suck air into the house before the roof vents do (for the water heater, furnace, radon, and gas dryer). Am I on the right track with this logic?

I'm definitely going to set up several carbon monoxide and smoke detectors to determine if there is any backdrafting. Hopefully this should do the trick! I will however discuss your points with my HVAC contractor. He will be annoyed as I already asked him about backdrafting and he laughed and stated it won't be an issue, but I want additional clarification.

"Obviously (I hope) one can make up for this by adopting a more powerful hood blower, if feasible. Or one can augment the MUA path with a blower."

In our case, the substantially cheaper route is to go with a stronger hood rather than augmenting the MUA path with a blower.

"There are places where outdoor air would advisably be filtered, and in these cases active MUA is needed because the pressure loss of the filtering is significant."

I'll be living in the country in Wisconsin, so outdoor air quality is good and doesn't really need to be filtered. I'll have a detailed conversation with my HVAC contractor in any case. Thank you!

I've done some more research as well as reading MUA threads, and also internalizing the advice on this thread. It seems to me I have two 'smart' options:

1) passive make up air system (and opening windows) used with a 500 CFM range hood or lower. Total cost: $800 (hood) + $650 (make up air) + $350 (ducting) = Roughly $2000

2) active make up air system used with a 900-1000 CFM hood

Total cost: $1300 (hood) + $2500 (fantech MUA with builder mark up) + $350 (ducting) + $1000 for an ERV or heater = Roughly $5500

Does anyone know if the heater or ERV is effectively required in an area with hot, humid summers and cold winters? My guess is that this is likely.

Given I'm going with an induction stove, but will have 45' of ducting through the roof, is this first option basically a waste of time (a poorly functioning range hood that does little to improve indoor air quality while cooking)? One other concern I have is maintenance costs: will the active make up air system last 10 years, 20 years with everyday use?

Thanks for all of the great advice--you've helped me tremendously in areas where my builder really should be doing better..

I can't imagine enduring a flow rate of, say, 600 CFM actual in Wisconsin winter without heating, unless one is a wolverine. Oil-fired hydronic heating feeding a heat exchanger might be the lowest cost per incremental BTU (if one has oil hydronic heat), but an electric coil system will have lower pressure loss and easier installation in many cases, and if cooking is not a lot of hours per day, perhaps not really significant in the overall electric bill. Both schemes should have long life, but predicting them in an absolute or relative manner would be difficult. ERVs would seem to be in-applicable to this issue because one cannot easily extract heat from the hood exhaust given the grease content.

Note: 1000 BTUh equals 0.29 KW, so for the higher flow rates and greater differential temperatures, with 240 Vac service significant current capability will be needed if MUA heating is electric.

A little confused: Isn't my actual CFM much lower than the rated CFM. For example, if I'm using the hood at 500 CFM max, isn't the actual CFM closer to 200 CFM? So, passive make up air with open windows during cooking in winter would only need to bring in 200 CFM. I probably would not need a heater in this case?

Regarding active MUA, your point is well taken. Heater necessary.

I would assume for the purpose of discussion that the actual air flow rate is 2/3 of the rated blower zero static pressure airflow rate. You can choose to install a hood system with performance anywhere you want in the range between mediocre air flow and attendant inadequate clearing of smoke and grease, and 90 CFM per entry aperture square foot actual airflow, which should be sufficient for most hot oil cooking, assuming that the hood entry aperture overlaps the plume diameters at the hood height.

I'm really leaning towards using a hood at no more than 500 CFMs (rated CFM). Cost is an issue. I don't do a ton of hot oil cooking, so perhaps I will still get by. Home Ventilating Institute recommends 300 CFM (actual) for a 36"hood against a wall. https://www.hvi.org/resources/publications/home-ventilation-guide-articles/how-much-ventilation-do-i-need/

I will talk with my HVAC contractor, but it sounds like I'll meet this HVI recommendation with 500 CFMs max (rated).

"assuming that the hood entry aperture overlaps the plume diameters at the hood height."

Regarding this, with all other variables being equal (hoods are the same design, manufacturer, same 30" mount height), I can spend $400 more on a 24" depth hood, or save the money and get a 22" depth. Again, CFMs will be capped at 500 (rated). What to do?

Thank you Kas and @opaone, and thanks to everyone else as well! I can finally see the finish line and it isn't a moment too soon.

"What to do?"

Cook oily and greasy items on the back burners.

Kas, this is good advice, so thanks. I do wish other posters would offer their experiences, as I feel kind of bad asking basic advice from an expert..

From reading forums last night, it sounds like 22" is standard depth, 24" is above standard, and 27" is extra depth. It sounds to me that either 22" or 24" will work, but I may miss some HOGS on the front burner. I guess I'm wondering, will that extra 2" depth makes a big difference? I've read some previous posts of yours that seem to suggest extra depth is always good (even if I'm primarily cooking on back burners), but that extra depth without extra CFMs is a little bit of an issue. These hoods will both operate at 500 CFM max.

The priority seems to be big enough for overlap, then affordable CFM up to 90 CFM/sq. ft. Assuming 10-degree from vertical plume expansion from the edges of the pans, as well as a somewhat wider gas combustion plume, you may wish to sketch the plume shape and compare it to. hood size and hood height and see how much is collected by each hood size given your actual burner locations relative to the back wall and likely pan sizes.

@Joe - what did u finally end up with?

we are doing new construct as well - I have a wolf 24"gas plus 15" induction - vented straight up through roof ( there is an upper level as well)....

All you people out there with suggestions - PLEASE advise !! Brands, CFMS, MUA, external blower ........

"Ask your local radiologist if they'd put an induction in their home. :-)" - lmao. Indeed. I haven't actually seen anyone with the temerity to post that here but I've often thought it.

I see you've gotten all the big guns to respond to your inquiry: congrats! It was well over a decade ago now that kaseki and clinresga and I think someone called "Kaz" maybe? weighed in on all of this for me. It was a slightly troublesome problem but their knowledge really makes a difference in working through issues: THANK YOU FOLKS. I pulled my hair out a bit, made a decision, and it was wonderful. TBH I don't well remember what it was so I can't pass it on but if anyone cares I'm sure it's in the archives. I found a disco wolf hood, took its branding off it, got a inline jet-engine level fan and have never had a problem. What's collected in the baffles of the hood never, ever fails to give me serious pause, knowing that formerly all that gunk has to have gone into our lungs. I used to wonder what the grime on the cabinets was. Can you imagine? smh.... stupidity. And its flip-side, knowledge.... a good thing. Even with an extremely high-powered fan it's still a struggle to get everything up and away, but very worth the effort imho.

Collateral benefit from a great ventilation system: eliminate excess fruit flies by setting fruit on the stovetop, as high as possible, then turn on the ventilation slowly: whoosh they're gone. :)

@3birdy: This thread, among a now vast number available here via searching, should have strongly hinted at the many factors that influence hood and MUA system choices. Your message above is inadequate for performing an analysis. After reviewing threads containing development of performance requirements, you should start a new thread with a better description of your kitchen and cooktop configuration.

"we are doing new construct as well"

I hope you didn't start construction before you and your kitchen designer made all the necessary choices in layout. This should have included the ventilation elements needed. An afterthought hood system entails a lot of performance risk, and maybe aesthetics and cost risk. This won't stop us from commenting, but it may affect your construction.

@kaseki - I did read the whole discussion as well as other similar ones. I also read Your article ( very well written !!) which put a whole new spin on the importance of the venting decision .... So now I am more informed, more diligent but even more scared of making the wrong choice!!

Fortunately, (??) my construction is not yet begun - sorry if i wasn't more clear - but i dont think my builder or HVAC person is best person to address this ... Kaseki seems to be more knowledgeable than both combined hence i am here asking for advice.

Pls let me know what other info you need to make a better analysis... your expert input is very much appreciated!

How do people here feel about the Victory Hurricane?

Please start a new thread specifying actual length of the cooktop surface (I'm unclear whether you have two assemblies, as I do, or one combo assembly). Specify whether the cooktop area is on a wall counter or an island/peninsula. Specify gas or induction or coil electric. Specify what is above the kitchen ceiling. Specify whether a Home Owner Association has a say in what you do. Specify general weather conditions summer and winter. Specify whether you cook with hot oils (such as wok cooking and/or meat searing) or with fragrant spices, odors from which must be kept out of the house. Budget may be important, although at this point you may not know what you should allocate.

For MUA purposes, specify whether you have an accessible attic, or clean basement, or mudroom. Specify whether you have any combustion appliances, such as a gas fired hot water heater. If so, specify whether the unit or units have their own ducted from the exterior make-up air or use air taken from the house where there is a connection to the kitchen.

After providing these details in a new thread, put a link to it into this thread so readers can find it. Assume nothing you wrote in this thread is to be assumed in the new thread; i.e., repeat it.

Please note that I only address requirements, and not particular hoods and components unless I own them. I will name sources that I know of for particular elements. Others can pipe up with their recommendations.

There is also a treatise by @opaone at https://bamasotan.us/range-exhaust-hood-faq/ that will provide perspective, as will the initial dozen or so pages of the Greenheck Guide, available at https://www.tagengineering.ca/wp-content/uploads/2015/02/KVSApplDesign_catalog.pdf.

"@Joe - what did u finally end up with?

we are doing new construct as well - I have a wolf 24"gas plus 15" induction - vented straight up through roof ( there is an upper level as well)...."

Hi @3birdy, I ended up going with the Victory Twister 22" depth model. I plan to build it out to bring it to 24" depth, fabricating a slanted metal piece to cover the 2" in the back. I went with this because I simply do not need the extra power of the Twister Max (also, I do not want to add an active MUA system as it adds about $3-4K in additional cost!), and the salespeople at Victory informed me that, especially with induction, I can safely hang the hood at 30" height above the range. Victory also shared that the Twister Max model is mainly for gas ranges, as the extra power is needed because the hood should be hung a little higher (32-34") so that the motor does not burn out from the gas heat. Problem is, as I mentioned, that with more power comes the need for an active MUA.

Regarding MUA, i will have a (mostly) passive MUA that is connected to my furnace blower, thus tempering the air before it is distributed into my home. I plan to use the hood at no higher than 500 CFMs (due to my passive MUA system), which is speed 2 of 4 (or speed 3 at 600CFMs for very limited time).

I received the Twister in the mail a few days ago, but won't be installing for another 4 months. However, I tested it and it is both quiet (although keep in mind, not attached to venting yet) and powerful, as well as extremely sturdy. I'm glad I went with it! Hope this helps!

@Joe - thanks a lot for the follow up!! I was seriously considering the Victory as well but the fact that it is not deep is leaving me in two minds... It is a strong contender though for now... I found a Broan model that is deep AND has a pretty decent CFM... now once I figure out the whole blower issue - in-line / external / internal... ??

Frankly I had not anticipated spending this amount of time and $$ on the hood decision.... I finished researching and picking the rest of the appliances and thought this would be easy but ....

help! @kaseki @opaone

ive read sooo many posts dating back to 2011 (i think) and you guys are so knowledgeable (definitely looking forward to trying some good scotch!). so today i went to a "high end" kitchen design place to ask about what to use for my 36 inch LP wolf range (which btw is totally pricing me out of the market for this neighborhood but cooking is my thing!) the high end place today said BEST is the best lol. when i mentioned to him what i had read (@opaone) that cfm isn't the main focus, he insisted how it's of major importance and the conversation pretty much ended there. the place i ordered the wolf is pushing ventahood bc it the quietest, easy to clean blah blah blah... and now i realize they have no clue. @kaseki your intricate knowledge is more than my brain can decipher, especially after all this top shelf scotch (in truth, we're talking rioja wines ha) so my point is this.......just tell me what to buy! i live in a tiny bungalo with a super low roof and would expect them to vent straight up through the roof. there's barely a space between the ceiling and the roof. help!

Broan/NuTone/Best make a large range of ventilation equipments and generally you get what you pay for as far as I can tell. However, why a "high end" appliance dealer wouldn't include some other brands is unclear. At a minimum, I would expect a Wolf dealer to have examples of Wolf hoods. (My hood is a Wolf, made by Independent before Wolf moved production in-house.)

Decide how high you want the hood for good site lines and reaching to the back burners, and missing one's head, while keeping in mind that the front burners will be emitting plumes that expand as they rise, so height corresponds to increases in needed overlap -- side to side and front to back. 10 degrees from vertical measured from the flame diameters when pans are on the burners can be used for plume expansion estimation. Sketch it out.

Given a height and hence width and depth, calculate the square footage of the entry aperture of the hood. For wall hoods the light bar in the front may qualify as partial or whole entry aperture area. Multiply area by 90 CFM/sq. ft. Multiply by 1.5 if you don't know all the pressure losses. Find a blower that has that result as a rated value. Decide on in-hood, in attic (in line), or on roof. Farther away is generally quieter. If there is room for a silencer (Fantech) between blower and hood then the result will be quieter still.

There is a lot of dissension about ease of hood cleaning by type. I can say that my Wolf hood baffle assemblies easily remove and can be cleaned in a dishwasher. (I have ten of these, so it takes two loads.) One still wants to reach up inside and wipe the surfaces. I use Simple Green, but likely there are myriad possible choices. I have never owned a VaH, and was initially repulsed (2007) by the Magic Lung® claims. Others like them. If you have guests sitting where they can see into the hood, a baffle system may be aesthetically superior.

Duct should be sized so that full power actual flow rate achieves a velocity in the duct between 1000 and 2000 ft/min for best balance between grease condensation and grease impingement. You can go lower (larger duct) if you pre-heat the duct in cold weather.

On CFM focus. Standard (if that actually ever applies) residential hoods are designed to fit into residential kitchens. Commercial hoods are designed to fit into commercial kitchens. At a minimum, the typical difference is two feet of ceiling height. When the commercial hood can be built so that there is tremendous volume below its baffles, there are conditions where the specific flow rate (CFM/sq. ft.) can be reduced below the value I suggested above. This is due to "baffle averaging" resulting from the reservoir volume vs. plume steady state and transient volumetric rates. At the other extreme, residential hoods with little volume below the baffles will allow plume escape (capture failure) if the plumes are not immediately entrained into the baffle flow. And, of course, plumes not initially captured are not contained and removed except as a matter of long term kitchen (and whole house) air replacement. So CFM focus varies.

Another difference is that commercial hoods are typically operated at a fixed CFM and the MUA is balanced for this case, whereas residential hoods, along with bathroom fans, etc., operate at variable CFM, and this makes the MUA control more complex.

@kaseki thank you! now reading about installing a silencer to help with the noise which is important to me as well as the other more important features!

I would add that until one sees just how big 10-inch duct is traversing an attic, along with a larger (14-inch diameter) silencer placed in the path, it is hard to appreciate how much space needs to be allocated. Even 8-inch duct and silencer (I use for an auxiliary vent over my ovens) is substantial. So I recommend thinking through the entire architecture, as well as how the hood is mounted to structure in the ceiling and how the ducting is fitted between attic joists or whether the joists have to be framed out and reinforced.

Access is desirable. After installation, even with ducting and silencer supported by strapping to the rafters, various blower motor induced vibrations may make their way down to the hood. This may call for wrapping the ducting / silencer in acoustic damping material.