IMHO, 300cfm is inadequate for almost any purpose other than noise-making. This is the upper limit of most OTR micro-waves and pretty much everybody that has one complains about high noise and low suction.

600cfm variable-speed with suitable capture-area hood (hood design is quite important!) will probably be fine. Fans are inherently noisy but many designs place the fan outside so noise inside is limited to air-flow only. Might take a little research, but they are not uncommon.

While a vent hood will remove some heat and gas cooktops do produce more heat than induction, the main purpose of the vent hood is to remove smoke, grease, and odors and those are produced by what you cook not which fuel you use to cook it. People who think they can get away with less ventilation with an induction cooktop are mistaken.

I'm going to induction in my remodel. My wife has a viking hood over her Viking gas range (4 x 15k BTU ), which at about 460 cfm is only adequate , so I think 450 to 600 cfm will be good for the induction. Like you, I'd like quiet. Most of the time, you will be able to use it at a lower fan setting, so even better. I don't fry or cook meat, so grease isn't really a concern (I don't even need to clean my hood filter screen once a year). If you cook more of these items, 600 cfm might be better.

I agree with what asolo and weissman said.

In addition, it has belatedly come to my attention that where the hood sucks the most air from (i.e., where the fan is within the hood space), should be considered in relation to where the largest burner is -- more accurately, the main source of most smoke / grease / odors.

For example, the fan in my Broan Allure III hood is on the left side within the hood opening. The filter directly under this fan clearly catches the most gunk, and air is pulled most efficiently from burners on the left rear of the cooktop below.

In my case, I think this (~430 cfm) hood might have been OK with my induction range, except that most smoke comes from the right front burner, and its just too far away for this hood to grab enough smoke (when I'm grilling steak on the only burner that fits my grill pan).

I am also wondering if the length of the exhaust duct to the outside has a bearing on total CFM"S..

billp1.....

Of course it does. As does the duct's diameter, angles in the path, and even the material it's made of. They have well-researched tables for all of it if you want to poke around.

600-700 would be the size I would get. Remember this is the rating on HIGH so look for one with multiple speeds. Take a look a Kobe and see if they have a style you like.

We cook nearly all vegetarian on an induction cooktop and went with a Futuro Concorde model. When the steam from the pasta water is boiling on the corner burner it is sucked up and doesn't impact the adjacent cabinets. Unfortunately the higher speeds are noisier than we had hoped for but it isn't a high pitch either.

I agree with previous posters. It isn't the lack of heat but the amount of steam and grease generated by your cooking that needs to guide your ventilation choice.

Thanks, everyone! Okay.....I see.....the consensus is that I need more CFM's as opposed to less, to insure that the steam and odors are adequately removed. There seems to be so many variables to the overall quietness of range hoods. Low sone ratings don't necessarily equate to low noise, I'm discovering.

The downdraft vent I have in my current kitchen is SO noisy that I virtually never use it unless I burn something. :-) I'd go mad in the small kitchen I'm designing if I had to work over a loud fan noise. (Loud is okay for a few minutes to deal with a heavy influx of steam, but for normal use I need it to be quiet).

I'm looking at several hoods.....
1. 30" Kitchen Aid KWCU405SSS.....expensive but slim profile for my small kitchen.
2. 30" Broan Model RM523004
3. 30" Zephyr Savona ZSAE30BS
4. 30" Bosch DKE9305AUC

Can anyone give me any feedback on any of them?
Weedmeister.....thanks for the Kobe suggestion. I did like them, but I want to buy one locally (not on the Internet) and nobody carries them here.

I'll agree that 450 CFM is better than 300, but I'd like to point out a few things. First, the manufacturer's ratings might not convey much meaning once you have your duct built. If it's longer than the manufacturer's test jig, their CFM rating can become close to meaningless. Second, if you tell us about your house construction standards, your climate, your HVAC and your plan for MUA, then we might get an idea how true it will be that a strong 450 CFM fan will do the job expected of it. Finally, describe to us the duct run you foresee (diameter and bends and lengths).

I had a similar situation to yours, and I got a fan all by itself (FG-6 from fantech.net) and built the rest around it to suit the requirements. It is quiet and it is strong, far stronger than the cheap fan it replaced which had a similar rating.

hth

Do not, under any circumstances, buy a Kobe hood. Their customer service is abysmal. You will be ok if the hood is in perfect shape and works when you install it. Otherwise, might as well say goodbye to your $$$.

huskerb - from your other post, it seems that you're upset with Kobe because you discovered a dent in your hood weeks after it was delivered. In fact, you'd have a similar problem with many other manufacturers as well. That's why it's always a good idea to unpack and inspect everything as soon as it's delivered to make sure there are no delivery problems.

davidro1.....thanks so much! It sounds like you know what you're talking about! I'll try to answer your questions about my situation, but please tell me what you mean by 'MUA'. (Sorry) :-)

First, we live in a cold climate (Indiana). We have a 1-story house, and the duct run will be straight up through the roof with no bends or turns.....about 6-8 feet. The diameter of the duct will be according to the specifications for the range hood (I think most were 6" or 7") My induction cooktop has a total wattage of 7200.

Considering that some gas burners are 15,000 BTU's, I would think that the induction cooktop (that we'll be using) would require much less CFM's than a gas cooktop.

If you need any more info, I'll try to provide it. Thanks again for your help!

MUA=make-up air.

MUA stands for make-up air. Make-up air is used to prevent back-drafting when a hood sucks all the fresh air out of a tightly sealed house. Generally with 600 CFMs or less you don't need makeup air but some locales in the northern states require makeup air with anything over 300 CFMs. Makeup air systems can be expensive - you need to check code in your area.

Thank you both for the MUA clarification. I guess I won't need to worry about that because I definitely plan to have a 600 CFM or less hood.

Almost. But, no.

You still need to know about what is happening, so you made good choices and they produce satisfactory results. When on high, some fans will turn the blades but not suck much air because there is not enough freely-available new air to replace the air that has already been exhausted. This means they will have created a slightly lower air pressure inside the house and they "can't find" new air at regular pressure to blow on out. So, then the blades are only turning in order to maintain the low pressure in the house. Fighting against the pressure differential, they will make a lot of noise. Completely unsatisfactory result for the homeowner who thought he was getting a strong fan.

Some houses look good inside and out but are as leaky as a tool shed or a barn; although "new" air will definitely be available to the exhaust fan, it will be not-the-best air to breathe if it slides in through cracks in stud cavities. For heating, some houses have electric baseboards, while some houses burn fossil fuels and this offers one possible way for "new" air to go to the exhaust fan, but it's not a satisfactory solution to the problem.

You can avoid this entire subject if you promise to crack open a window near the kitchen in the middle of winter when you want to put the fan on high. Or, you can add more information to this thread and see what feedback comes back. For you to be satisfied at the end of the whole analysis and buying process, you need to know what the physical constraints are, how seriously to take them and when they can be ignored. Many of the posts above were from people who were not satisfied with their 300 cfm fans; but a 450 or 600 cfm fan may be also unsatisfactory. Much depends on other factors: it's not just the fan.

davidro1.....well, you've just corroborated what I've been discovering....that is, it's a complicated combination of factors that will lead to the ideal exhaust situation. Maybe a little luck too? :-) As you were 'talking' I was wondering how you're supposed to get the 'new air' for the exhaust to draw from. Of course, the window is a good idea (I'll have to remember that), but short of that, how do you ensure that happens?

Our house was built in the 50's, but we've gutted it and are making everything new. We've re-insulated the exterior walls and put in new doors and windows, so the house should be pretty tight. We heat with a gas furnace.

I know there are other factors too, like internal vs. external motors, blah blah blah.....I just don't understand that stuff. Basically, I don't mind a loud noise for a few minutes to get the really awful stuff cleared out, but when I'm sauteing onions or garlic, I just want a steady suction so that my house won't smell like onions. I don't think that would require a high speed.

yes, I agree this won't require a high speed.

We have a pretty basic Broan range hood over our induction, and it seems to vent adequately to pick up the steam, etc. It does vent to the outside if that makes any difference. It is much better and quieter than the one we had previously, even on full power. We used our existing cabinets and duct, so our options were limited as to what would work in that space.

I know some people who don't even have a vent hood in their older homes.

gsciencechick......I've NEVER had any kind of ventilation in my house. Well, I mean....I have a downdraft vent, but it's a joke and I've never used it. And I cook a lot, so odors stay in my house for days! I really want a hood that I can actually USE, and one that's quiet enough to use much of the time.

Thanks for the feedback on the Broan. Ours needs to be a wall/chimney style (no cabinets above), but it will also vent to the outside.

Now my next questions is.....how do you like your induction cooktop? I'm going with one for the first time, and I can't really read too many negative things from people about them. Any tips you'd like to share regarding the induction? As of now, we're considering the Bosch 500 cooktop.

Thanks so much!

I've been using my GE 30" induction cooktop for 6 weeks now. I've always used & loved gas, but where we just move to it had to be electric--yuck! When I learned about induction, I got a portable unit to try it and loved it. De-cided it was the way to go. In many ways its even better than gas, since there is IMMEDIATE response in your pan, whether increasing or decreasing power; faster boiling; surface around the hob is cool; no heat in your face from the gas. I bought a square griddle which is slightly larger than my largest hob, and the part that isn't on the hob doesn't heat. To my mind that's the only drawback--I may have to get another, smaller griddle, or get a separate electric griddle. I really do like induction & get a kick out of using it. It is also totally silent. I know some people complain (or note) there is some noise, but I haven't had that experience. You must also have the right pans, and then there is no sound from them, either.

The next concept to wrap your mind around is the canopy capture volume of the hood shape. It's an upside down container like a sink. Rising steam (containing lots of airborne grease droplets) moves so fast that it cannot be captured by the vent suction alone; it needs a temporary holding pen. All the fans mentioned so far and in other threads have a flat bottom, not good for this. They may be good looking according to the trends of the decade, but they don't work well.

I am trying to wrap my head around all the venting info- it is confusing and at times I want to throw my hands in the air and just pick one! With regards to MUA - how the heck do you know if you need it, and, where does it come from?

"Thank you both for the MUA clarification. I guess I won't need to worry about that because I definitely plan to have a 600 CFM or less hood."

You should still call your city planning department, or whoever it is that issues building permits, to check. Where I live they require MUA for anything over 400 CFM.

Yes, as ideagirl2 says, definitely double check the MUA with your local AHJ. I'll also say: take nothing for truth that you read in internet discussion threads; always talk to "humans" in person, too. But don't rely on what a minimum wage person standing in the aisle of a hardware store tells you, because they are the most likely to steer you wrong, of all the people who appear to know what they are doing.

Going with 400 CFM you find that the general consensus is that one does not need a specific plan to provide MUA specifically as MUA, because the house's normal air leaks are deemed to be good enough. And, you can open a window a crack just as you would for a fireplace or a wood stove.

((By the way, really good planning for wood fireplaces and wood stoves involved having a small flow of cold outdoor air come through a pipe in the wall and go directly into the fireplace. It gives the fire oxygen. No need to pull cold fresh air into the house through air leaks, then heat it as part of the house's heated air, and then have it go up the chimney as waste...))

Based on the cooking style you have expressed, fiddleddd, you will be happy with capture containment and extraction in the range of 3-400 CFM. Final answer.
hth

I made the mistake with my kitchen remodel of giving loads of thought to the range I wanted and then found out about our township's dreaded Make Up Air Requirement for hoods over 400 CFM. We've consulted with many experts and concluded that our house presents issues that complicate installation of the make up air system so we decided to go with induction which I am really excited about. Of course I'd rather go above 400 CFM's but without the Make Up Air system the township won't approve us, even if we promise to open the window as needed-- which, I should add is my present exhaust approach as we don't have a functional hood. David, I like your "final answer"...but what hood shape is best? Our design requires a chimney hood. I'm curious if you agree the location of the fan within the hood makes a difference in the effectiveness of the exhaust? We were hoping to eliminate all food smells such as the yukky smell from the breakfast sausages my son just threw on the stove. Thanks to everyone for educating us on induction and suction.

A shower pan holds a lot of water before it lets anything overflow. A sink too. They are different shapes but they both work, because the sides are continuous and level. Turned upside down they would work well too if the sides were level. Smoky air is lightweight and will rise fast. When captured in a "basin upside down" this lightweight air will displace heavier air and remain in the pan / sink / basin / container / canopy shape. It's a temporary holding pen. The fan which was already turned on a few minutes before the smoke occurred (hint hint) is already sucking/ extracting / exhausting / pulling air out of the kitchen cooktop area, and to accompany this extraction process you need some form of container to hold the second-by-second overflow. Hope this helps. I have no specific remarks to make about where to place the fan or the vent opening inside this canopy.

leel.....glad to get your feedback on the induction. Thanks!
As for me, I certainly wouldn't mind having to buy a new pan or 2 for the new oven. :-)

gsciencechick....thanks for the pots and pans suggestions and the confirmation about induction. I'm ready to be done with gas (although I love the way it cooks) because it's just so dirty to keep clean.

muskokascp.....I HEAR you!!! Whatever happened to the days when we just went to the store and asked the opinion of the saleman or perhaps picked out a unit because of style or color? These days we almost have too much info, and it can become crippling, honestly. At some point I just need to make a decision.

davidro1.....I love your 'final answer' comment. I WISH!!!! Although I certainly know a lot more than I knew before, I still have questions. But today at the appliance store helped clear up some things. (Meaning that they don't know anything either and I can basically do whatever I want). The inspector on our job (both HVAC and electrical) don't know anything about MUA and can't advise us what we should get. So I just told them I'd get something that wasn't too powerful, and they seemed fine with that. They told us to adhere to the recommendations in the manual that comes with the hood. I swear!!! It's not rocket science.....why is it that nobody knows about this technology?

davidro1 and cindylood......I tried sending a separate not to cindylood, but it wouldn't go for some reason, so I'm sending a new note to both of you.

cindylood.....something I tried. I turned on the hood to its lowest setting. Then I placed a piece of paper toward the front of the fan to see if the fan would hold the paper in place. I particularly wanted to see if it would pull from the front burners. The fans for the most part seemed to capture most of the cooktop. It improved on a higher fan setting. I'm sure the kind of hood davidro1 describes is better, but they're also way more expensive, and they're not in our budget.

I do have to tell you about my experience today though. I was in a local appliance store (an independent store, but a big one). They simply could not and would not recommend any range hood except Vent-a-Hood. Never mind that they don't have a style that will work in my kitchen. I need a chimney hood, and all of that style were way too bulky for my small kitchen.

I understand the centrifugal blower concept that Vent-a-Hood has, but honestly......you can't tell me that's the ONLY decent hood made today. I was a little miffed that these 'experts' would not be more helpful than this. I'm getting more help here on GW!!!! :-) Thanks for letting me vent.

Fiddle, it's good you can vent here cause I'm not sure our hoods are going to do so. I agree that the info gained on GW and other internet blogs has proven much more beneficial than info picked up from the folks selling the ranges and hoods, and those installing them, and the regulators who are going to enforce the code. I've come to realize that you really can't rely on the salespeople regardless of how reputable the store is. They will basically only tell you about brands and products they sell (or want to sell)...and they don't tend to share the downsides of products. I was lucky to hook up with a terrific salesperson who has put a lot of time into helping us wrap up our appliance selection. We've selected a Best By Broan chimney hood, 400 CFM, model K313936 -- the price was far cheaper than the Vent-a-Hood and we weren't sold on the looks or functionality of the VAH models. It was sooo much easier in the old days when we just went to Sears for everything Kenmore. I agree that too much info can overwhelm you -- the bloggers lead you to believe that nothing is 100% reliable.

I have the Kenmore induction range -- I love it -- it is a joy to cook on and I cook a lot!

I have the Zephyr Tamburo hood (I think it is 400CFM) over top. I have had the hood for almost six years and I also like it very much.

I keep it on low for most things and sometimes medium. The only time I use high speed is when I am cooking bacon. High speed is noisy and gets annoying.

Mine vents straight out the wall to the outside.

My hood is 36" not 30" (kitchen designer recommended it). Overall, I like it -- my only complaint would be that the light bulbs burn out too often and are expensive.

cindylood......don't you feel great to have finally made a decision? :-) We're actually considering the same hood, but in the 30" size. It's one of 3 choices at the moment. If you think of it, I'd love it if you could report back on it for me. I'm specifically interested in how quiet it is.

I have the luxury of waiting a bit to order my hood. I WAS in a hurry because I had found a hood on Overstock.com for an incredible price, and it was in danger of being sold out. As it turns out, we've decided we aren't interested in the Overstock.com choices.

It sounds like you got a great sales person....lucky you! I hope you end up being happy with your choice. I wish that for us all! :-)

stir fryi.....I've heard that you're supposed to go with a hood larger than your cooktop. We just don't have the room. But I figure that our hood will at least cover the burners, if not the entire cooktop, so it should be fine. Thanks for your vote of confidence about the induction. I keep telling myself (a diehard gas user) that I'm doing the right thing!

Yes I do feel great -- sort of like jumping out of the plane: I know I'm going to reach the ground and I'm counting on the chute opening. When I visited my fav salesperson yesterday, I asked her is she could give me an idea of what 6.0 sones sounded like. The showroom has many products hooked up in a real kitchen setting -- you are encouraged to cook at the store to see if you really like what you are getting. While the hood I was interested in wasn't on display, she did demo another Best hood so that I could get a sense of the noise level at 400 CFMs. While the lower level settings aren't bad at all, the highest level reminds me a bit of my hair dryer. But I put up with the sound each morning so I'll get used to it in the kitchen. I'll keep you posted as to how things work out -- our install should occur around mid-December. Can't believe my husband is actually getting psyched about going the induction route...of course we have a lot to learn about how to cook on induction...like how do you wok cooking? I figure all this time I've committed to picking out appliances, flooring, etc can now be spent on learning how to cook. Hope your search ends soon too.

cindylood.....I'm getting psyched about the induction too.....in fact, our entire remodel. I've heard only good things about induction, including from life-long gas users. I'm an avid cook though, and I'm sure there will be a learning curve for me. Best of luck with all of your renovations.