A 36-inch induction cooktop's ventilation needs are pretty much independent of the cooktop manufacturer. To collect rising and expanding cooking plumes, the hood should overlap the potential pan edges by enough to collect the plume area at the entrance to the hood. Three inches larger than the cooktop at all edges should be enough at 30 - 36 inches of hood height.

The volumetric air flow rate (CFM) should be sufficient to keep the captured plumes from reflecting out of the hood. This somewhat depends on what is cooked, how hot the pan surface is, and whether or not there is a significant volume below the hood filter (which preferably should be baffles). For residential hoods there usually is not significant volume.

CFM for induction cooktops performing typical residential cooking should not be less than 60 ft/min times the area of the hood entry aperture (in square feet), and for wok cooking or searing, 90 ft/min times this area.

These are actual flow rates, and NOT the rated flow rate of some blower used in the hood ventilation system. Without knowledge of pressure losses in the baffles, ducting, and most importantly, the air returned to the kitchen from outside (make-up air -- MUA), the value calculated from the 60 or 90 value should be multiplied by 1.5 in the hope of ending up at an adequate flow rate given the particular blower's "fan curve."

@kaseki

Thanks for the info. Does an induction cooktop take a different hood vent than and regular electric smooth cooktop? My setup right now is a KitchenAid microwave over my smooth cooktop and it seems useless and very loud even at the lowest speed.

No, hood requirements depend on cooking plume characteristics. Gas burners tend to cause larger, hotter, higher speed plumes than induction or coil, but .... if one is doing very vigorous cooking such that, say, peanut oil is vaporizing, or grease is splattering, then the cooking plume can dominate the gas combustion plume. So for serious pan cooking, we can almost (!) ignore the heat source. (The plume velocity can vary quite a bit, so I am being very approximate here, and how the gas flame transfers heat vs. just flowing around the pan can make a difference.) When griddles, or char broilers, or other large heat emitters are present, then the flow rate requirements may have to increase.

Microwave oven ventilation is nearly useless, and it isn't just your particular unit. They have inadequate flow rate and inadequate capture area and inadequate filtering. All my comments refer to real hoods mounted above the cooktop intended to capture and contain rising plumes. In return for actual grease, odor, and moisture removal from the house, along with tolerable or in some cases quiet operation, one has to pay more and allocate more space.

Heat is heat. What kind of hood you specify depends much more on what kind of cooking you do than the stovetop technology itself. If you're doing high-heat cooking, searing meats or cooking with a wok, you'll want to be sure you've got a powerful enough hood to draw the kind of steam, grease, and odors that come with. If you're just doing light sauteing and boiling, then hood power/velocity is less important. Regardless, I'd be sure that the hood is at least the size of the cooktop, ideally a little larger on all sides. Good luck!

@Parco Studio

Thanks, I would like to at least have a 42". I think most places I read that it should be at least 3" or each side of the size of the cooktop. I have never had a hood vent so I don't know what brands to look at. We don't have any stores close so that I can look at them. The closest is 370 miles (Casper) round trip or 400 miles (Billings) round trip.

3" on all sides sounds right. I would also look for a hood where you can vary the fan speed. This way you can get the velocity you need when you need it but a quieter operation when you don't. A hood that really draws will be noisy but that's the only way to manage the plume created from any serious cooking.

I don't have any specific recommendations but would do an internet search, maybe making yourself a little spreadsheet with brands, models, variability, and CFM (cubic feet per minute) of draw, and of course price.

One rule of thumb is 100 CFM per 10,000 BTUs of heat. With 5 burners, you'd have to add up the max BTU of all 5 burners to see what kind of heat you could be generating if you were really cooking up a storm.

A lot of vents are noisemakers and that's about it. I redesigned my kitchen 18 years ago and was advised that hood wasn't necessary/in building code. True statement by those experienced appliance men who really SHOULD have been trying to sell me a vent. They didn't - they shared valuable information with me. I'm a healthy cook (no frying) also not cooking curry and other extremely fragrant foods. I've only missed the hood maybe twice a year -- when I cook wild rice, then I open the window to refresh the kitchen.

My cooktop is on the island, 8 foot ceilings and can lights above. I'm in the midst of complete gut of kitchen and don't plan to put one in -- consulted with a lot of cooks and realtors before reaching that conclusion. Most fans aren't doing anything productive. I did see one brand that appealed to me -- It's a pop up that rises from the counter/cabinet by Best. Good luck.

@Parco Studio

Thanks for this information. I will keep it in mind.

Of course.

Also seeing Denise W's comment above. Just to be clear, there's a huge difference between a fan and a vented hood. If you're doing any kind of serious cooking, you need to stay away from fans. And while some downdraft "hoods" are vented, they don't work very well. A vented, overhead hood is the best way to go IMO.

Incidentally, I'm a trained chef in addition to being an architect so I my comments lean towards fairly intense, high heat cooking. You may not have the same kind of need.

Good luck with it!

-Ben Parco

@Denise W

Thanks for your comments. My Microwave vent is really noisy on the lowest setting and does absolutely nothing--which others have said that they are useless.

It is really difficult for me to open windows--just as soon as I do we have a strong wind that blows in red dirt.

@Parco Studio

Do you give cooking lessons and design lessons. I don't seem to be doing either one of them right.

I used to be a pretty good baker but since I moved to Wyoming nothing seems to turn out the way it is supposed to. I am really struggling with my replacement Fridgidaire Double ovens--A piece of JUNK!!!!

I love living in a small town but being so far away from things is not FUN!!!!

Ha! I'm about to launch a YouTube channel for architects, architectural clients, and anyone interested in design, so stay tuned for that. As for cooking lessons, maybe that will be YouTube channel #2. ; )

Sounds nice there. Having been in oh so busy San Francisco for over 30 years, I'm feeling the draw towards a simpler life.

@wyosue58 What is the elevation where you live? Altitude has a hugh effect on baking.

I used to live in Colorado, all baking recipes had to be adjusted for baking at 6000ft.

Look up baking at elevation to learn how to adjust your recipes to work at your altitude.

@grioux

Thanks, I think we are at 3500 ft and everything I have read says we don't have to change anything. A few years ago I tried their changes and it did not make any difference.

Edit: It is actually 4,300 ft

@Parco Studio

I grew up in San Diego but I could never go back there to live.

I get it.

@Parco Studio

Do you know anything about Farber Hood vents?

I've never specified a Faber hood but they look pretty nice. Having owned a few Italian sports cars in my life, I'm often dubious of Italian made machines but hoods are way less complex than cars so I'd guess you're safe. I would look for reviews online. And... I'll be adding these to my list of equipment to investigate more closely. Thanks!

@Parco Studio

After I posted this I did look at reviews and they were not very good. Thanks,

Ventahood makes a great hood. https://ventahood.com/ - Another good one is Zephyr.

We have a 36” induction cooktop in an island, too. We mostly sauté and really do not cook very much. For us, the pop-up fully vented GE (goes down, through the basement, and out, using an additional fan motor in the basement) works well enough. We do sometimes have to open the skylight, which is next to the area where the cooktop is, or the window, but more with the oven than the cooktop. You can see the steam going into the pop-up vent, and in 10 years, our ceiling above the cooktop is not dirty.

@Design Girl

I have been looking at Proliner, Vent a Hood, and Zephyr but of course it is all Greek to me.

This is what I found on Vent a Hood but it does not make sense to me. Below is what it says on Vent A Hood's website.

** EQUIV CFM : Because the Magic Lung® blower uses centrifugal filtration rather than conventional baffle or mesh filters, the Magic Lung® blower can handle cooking equipment with higher cubic feet per minute (CFM) requirements and can deliver equivalent CFM much more efficiently than other filtration systems. When comparing the Magic Lung® with other blower units made by other manufacturers, use the “Equivalent CFM”.

@wyosue58 - I will defer to someone with more technical knowledge than I have. I just know that Ventahood and Zephyr are well regarded. Can you call an appliance store and talk to someone about what your requirements are? They may be able to point you in the right direction.

I have addressed the VaH magic several times. Here is a summary. Without baffles or mesh filtering, there is little hood pressure loss. With them there is, so filtered hoods move the blower operating point up the fan curve (see example of a fan curve below) and down the CFM abscissa. Whether or not the "magic" factor of 1.5 occurs depends on the blower design.

But now we have to invoke the fact that the VaH and conventional hoods' actual operating conditions are with ducts and make-up air pressure losses, so both hood types will have further reductions in flow rate. As it happens, many blower types used with conventional hoods, particularly those external to the hoods, have more useful fan curves under conditions of pressure loss than the squirrel cage blowers used by VaH. So one has to compare the actual VaH blower and hood performance vs. all the pressure losses (data sometimes available on VaH web site) to the other blower type fan curve vs. hood baffles plus everything else pressure loss.

Because the VaH fan curve is apparently flatter than centrifugal or axial fans fan curves, there is some amount of duct/MUA loss where a 600 CFM VaH (claiming 900 CFM equivalent) will have the same flow rate as an alternative blower claiming 600 CFM at zero static pressure. And I would take a stab and guess this is in the 500 CFM region. More pressure loss and the VaH flow rate drops more precipitously than the conventional blower.

In any case, the 600 CFM VaH will be moving less than 600 CFM, and the 900 CFM conventional blower in a conventional hood will be moving less than 900 CFM, and which is higher flow in some household condition requires analysis.

I should add that the VaH factor of 1.5 is the same factor I give for full performance of conventional hoods with conventional conditions. So with moderately adequate MUA, and reasonable duct lengths, I would guess that the 900 CFM conventional blower with baffled hood would reach 600 CFM, and the 600 CFM "equivalent" VaH hood system would be lower at 500 CFM or worse.

I went with a Zephyr 42” with my 36” induction cooktop.

@kaseki

Thanks for this information but it is still all Greek to me.

@kaseki - You seem to be VERY knowledgeable, but I have no idea what all that means. I will also be getting a 42 inch hood over a 36 inch induction cooktop. Vent and cooktop are on an outside wall. I'd love it if someone could tell me what I need. Hood will be an insert, as I am having a custom cabinet hood made by the cabinet builder.

@kaseki

I thank you for all of this information. I spent all night watching videos and comparing the different products but some of the companies seem to contradict themselves. Of course, that was even more confusing.

All I want is something that is quiet, easy to clean, lots of lighting, and works without any issues.

I am at the tail end of a complete kitchen remodel in home we bought new and have lived in for 34 years after a leak under dishwasher got into exterior walls of kitchen and adjoining dining room . We decided it as time for a kitchen remodel anyway so we bought all GE Cafe new appliances including a 36" 91,000 BTU max with six burners gas cooktop. The previous one was a smaller 30" GE gas with a 6" duct venting to outside. The kitchen has 8 foot ceiling, We raised the countetops when Cambria quartz as installed over newly built custom cabinets in an island type arrangement (more like a peninsula) so there is around 54 inches above the burners to the ceiling, There is a space that is around 39" between the upper cabinets where the Venthood will be installed/suspended. Previously there was a small Range-aire built in a cabinet that as connected to cabinets on both sides that was above the old gas cooktop that was removed along with the previous cabinets. Its only two of us so the gas cooktop we bought is an overkill as we wont be using all six burners at once. We wanted the appliances (Double Oven, Refrigerator, 30" Microwave, dishwasher and gas cooklop (All GE CAFE in white Matte finish with brushed Bronze handles) to match but GE did not sell a 30" cooktop in their GE Cafe line. After reading a lot of online articles it seems as if we should be buying a Rangehood with a minimum 900-1100 CFM blower which would require a larger duct (8'' to 10"?). There is currently a hole in the ceiling with the old 6" diameter duct hanging out of the hole awaiting a decision about a venthood purchase. The 6" duct goes about 7 to 9 feet to the outside with a flap right outside the door in the adjoining dining room . The flap on the brick wall is just outside the door to the right . My contractor says I am making a big deal over the power of the blower required of the CFM for our small kitchen now with a larger 36" gas cooktop and says its not necessary to to tear up the upper cabinets and put a larger diameter ducting instead of the 6' currently in place. I'm not so sure and dont know who else I should talk to before buying the appripriately sized venthood. It also seems like that any venthood we buy we will have to cut the chimney a bit shorter maybe to 24" to allow 30" above the burners as recommended by various articles ive read. I also see that ideally you should have your Venthood be around 4 to 6 inches wider that the cooktop but we only have 39" max to work with between the upper cabinets which are now in place so we most likely will have to go with a 36" wide venthood as they are made in 36" and 42' widths. The installed GE CAFE cooktop is 36" wide Sorry this is so long but seeking advice as what do to. .

Carl wrote, in part: "... we are at the tail end ... " Sorry that you missed the note somewhere that the entire kitchen as a system needs to be defined before buying anything and particularly before defining cabinets and cutting duct paths. The kitchen system has to include both the hood system and the make-up air system. Both of these can (in some cases) be relatively non-complex, but one has to analyze air flow requirements and components that achieve them in order to know what to buy.

I can recommend parameters that will achieve sufficient air flow in most cases, particularly including hot oil cooking. These are the same as recommended in myriad topics here over the past decade or so, and should have been reviewed when thoughts of kitchen ventilation first occurred. High school math is needed.

In summary, for capture the hood has to overlap the rising and expanding (i.e., conical) cooking plumes that are emitted over the surfaces of pots and pans. A 10-degree angle to vertical may be used.* Side cabinets should aid capture and allow a small reduction in hood width. Cooking odorous stuff in the cooktop center can help. Front-to-back "depth" has similar requirements, except that for wall placements, the wall acts as an extended capture boundary. So ideally, for a 36-inch cooktop, that may have front pan edges at 18 to 20 inches from the wall, a 22-inch or greater hood depth is desirable. The 3-inches each side is desirable. Note that the rising plumes are also susceptible to cross drafts and turbulence from human movement, so bigger than the cone limit is better the higher one sets the hood base.

For containment, the air velocity entering the base aperture of the hood has to be high enough to ensure that all effluent is entrained into the flow that goes through the baffles. This varies with the plume velocity, the volume under the baffles, and general configuration of internal reflecting surfaces. I recommend 90 ft/min across the area of the hood base, and this translates to 90 CFM per square foot of hood entry aperture.

For blower rating, the fan curve of the blower has to be accounted for vs. pressure losses (air friction) of baffles, hood transitions, ducts, wall or roof caps, and of course, the make-up air (MUA) balance vs. house pressure. As alluded to way up this thread, a factor of 1.5 times the required containment flow rate determined from the paragraph above may suffice if the MUA is sufficient.

Duct diameter should keep full power flow velocity (duct CFM/duct sectional area) in the range of 1000 to 2000 ft/min.

MUA I will defer for now.

If you will edit your word salad into paragraphs I will look to see what questions I missed answering.

______

* The plume is actually a distribution function that varies with moisture and grease content, pan surface temperature, and whether the heat source is induction, gas, electric coil, hot coals, etc. 10-degrees should be sufficient to balance the wider plume "rays" against their more easily entrained lower upward velocities.

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