Some good info here: https://www.houzz.com/discussions/5161173/hood-faq

DO NOT vent to the attic. Yes, your hood s/b at least 6" wider than your range.

Is your range gas, induction or dual? What styles of cooking do you do and how often? Do you entertain much?

If you get a stove with a down draft as well as install a venting fan you will have the best of all worlds...but the overhead vent must vent out doors ..with the vent going straight up through the attic to the outdoors..neither recycling thru a filter or bending to go out the wall will do the job properly..

Down draft must vent outdoors as well...

I'll check that thread out, thank you!

Our stove is electric. We brown a lot of hamburger for things-spaghetti, lasagna, goulash, chili, meatloaf, etc. Quick/easy stuff generally. We like breakfast for supper, so eggs, hashbrowns at times. Bacon. I suppose it would average out to once a day w/being gone for work most of the day during the week. We don't entertain much...we would maybe have people over, but the place has been torn apart for so long, and husband's hours compared to everyone else aren't conducive a lot of the time.

Great googly moogly that's a whooole lotta info..I knew it wasn't going to be as easy thing! Dangit.

If you’re not going to do cabinets on the wall, just get an inexpensive stainless chimney hood.

https://www.lowes.com/pd/Broan-Convertible-Stainless-Steel-Wall-Mounted-Range-Hood-Common-36-Inch-Actual-36-in/3102223

btydrvn wrote, in part " ..with the vent going straight up through the attic to the outdoors..neither recycling thru a filter or bending to go out the wall..."

I'm not sure what this means, but the hood has to have a fire stop, and this function is performed by the baffles or mesh filters that the hood supports. Also, these remove the larger end of the grease particulate spectrum keeping the duct walls from greasing up.

Bends as needed are OK so long as the blower has the capability to move the needed CFM against the increased pressure loss. The duct can be angled in the attic to move the exhaust point to a desirable point on the roof.

In numerous threads here the requirements are spelled out. Plume expansion ==> Hood overlap. Air velocity ==> Volumetric airflow rate. Duct velocity==> Duct size. Compensating for pressure loss ==> blower sizing. Make-up air. Search the forum and ye shall gain insight.

Do not vent into an attic or into a crawl space, but you may vent through an attic or crawl space.

Plumes rise due to their air/grease temperature. Attempts to capture them by side-draft or down draft schemes will fail.

That Braun hood will perform quite poorly and would be a waste of money. It has zero containment area so most of the gook (effluent) rising up from the range will just roll out from under it and spread throughout the kitchen and house.

You want one that has a large opening at the bottom and a bunch of open space with the baffle filters up in it.

She has a plain Jane electric range, and is starting from 0 with no real hood. It’ll be fine for that, on a budget. No, it’s not the perfect. Perfect doesn’t need to be the enemy of the good. Whatcha got under $500 in a chimney? Anything with better specs, easily orderable with local points of contact, and not too ugly?

They're going back up in the attic soon to look, but aren't sure what's up there for venting to connect to or where it is, and I'm not sure how much of a project it would be to cut thru the roof.

Venting in to the attic poses numerous problems including fire danger, attracting bugs and rodents, and damage to wood structural members. You do NOT want to vent in to the attic. Cutting through the roof and installing a proper roof jack should not be too expensive.

@User, that hood will exhaust only perhaps 10-20% of the effluent with 80-90% rolling out from under it and expanding throughout her kitchen and house.. Yes, it's good that she doesn't need to worry about byproducts of gas combustion, but did you see the cooking she does? Browning hamburger and hash browns, cooking bacon? Those produce a lot of greasy smelly effluent. That chimney hood looks nice but will only be marginally better than what she currently has. Marginally better may be good enough if she doesn't mind the smell of meals past permeating her home but why not find a hood that will perform much better?

You can’t vent to the attic but through it I often use hoods the same size as the range but just up the CFMs you can also get a through the wall vent hood so check that out if the attic is not going to work and your stove is on an outside wall. I like vent-a-hoods , they are not cheap but work well. I would suggest doing bacon in your MW with paer towels the grease goes into the towels and the bacon cooks up very nicely.When our kids were home on a day off I often browned and bagged ground beef and froze it so it made a greasy mess once instead of too often .I usually made spaghetti sause that day too. Downdrafts are useless for venting and do not improve with adding a hood to them, Remember the farther you have to go the more CFM you need and bends also need you to up the CFMs.

A VENTING FAN is installed in the ceiling..venting to the outside...it works excellently to catch all smoke etc...that escapes the downdraft stove...it is also used in summertime to vent hot air that has risen to the ceiling...in lieu of turning on the air conditioner...and removes all cooking odors that would otherwise spread throughout the whole house in an open floor plan....please note my post did not mention Hood...it was my mistake to not be more clear as it is not a common solution...we chose this option as we live in the country and like to avoid AC and because we live in a rural setting where we like to leave the doors open for fresh air...this also works well for us as we have 13 foot ceilings...and 50 feet of windows that let a lot of sun in

A ceiling venting fan is very economical to buy as well as very inexpensive to run compared to AC

Sadly the stove isn't on an outside wall. Maybe they can find something in the attic already there that they can run it to. If we'd not ended up w/a freak blizzard today they could've looked, but we shooed them home, thankfully before they pulled the plows off the roads!

So I was looking at them online last night on Home Depot, and there are ductless ones-I assume that's like an under cabinet one, just w/a chimney attached instead of a cabinet?

Where is a good starting point for CFM?

"Where is a good starting point for CFM?"

The short answer is in hundreds of threads on this forum.

A longer answer summarizing the subject is provided below. Note that it is your house and you can do anything you want, so long as it isn't a fire hazard or a combustion appliance back-draft hazard.

Cooking plumes expand as they rise. They should be captured before having a chance to deposit grease and moisture on house surfaces. This requires a hood canopy that overlaps the extent of all likely cooking plumes. For common residential hood distances above the cooking surface -- 30 to 36 inches -- overlapping the cooktop by three inches all around is considered acceptable. More details may be found in other threads.

Once the size of the hood entry aperture is obtained, the area is calculated. For hot cooking (includes wok cooking, searing, grilling, etc., a hood air velocity around 90 ft/min is desirable for containment (effluent stays in the hood). This implies that the hood volumetric flow rate should be 90 ft/min x hood entry area ( sq. ft.) to yield cubic feet per minute. For modest cooking where maximum plume velocities are not generated, then a lower number such as 60 ft/min may be adequate. Note that the desirable CFM is determined by cooking technique and hot gasses, and not by how modest the range might be.

If you were to use a ceiling register, then the area would have to be much larger and the velocity scaled to the plume velocity at the ceiling, leading to a large area with more CFM. Even so, cross drafts might defeat capture. Cleaning the filters at the ceiling could be difficult.

With the required CFM determined, the required blower rated performance can be estimated. In short, multiply the required CFM by 1.5 to choose a blower capability.

The duct should be sized so that the actual flow rate causes a velocity not to exceed 2000 ft/min, but preferably closer to 1000 ft/min.

I'm not going to fully address make-up air in this comment. There is always make-up air for whatever the hood is able to move out of the house, but if the MUA is restricted, the hood blower is also restricted and does not flow at the desired CFM.

And the reason I am still writing this stuff is to overcome the mal-information that still seems to be perpetuated on this subject. A venting fan cannot capture and contain all of the cooking effluent before it condenses on surfaces because the venting fan capture area is too small. If it seems to it is only because the grease on the ceiling is not obvious. A whole house fan (few thousand CFM) might develop enough air flow (with open windows) to capture the rising effluent due to air flow along the ceiling, but this is not a desirable solution because ducting to the outside would be ridiculously large.

Hi, kaseki I have been reading a lot of your comments/reviews on range hoods and saw that you went from VAH to a Wolf hood. Would you mind sharing your experiences? Is it powerful? Is it quiet? Is it easy to clean? Thank you so much for all your contributions on this topic.

[Psst. You should probably have started a new thread, S + U.]

A never considered a VaH beyond observing one in an appliance store near Portsmouth NH. I will admit to being 'turned off' by the "magic lung" claims. I quickly discovered that there seemed to be no engineering science behind what was touted in stores w.r.t. hoods, so I investigated and found a vast literature out 'there' mostly aimed at commercial kitchen ventilation. With some reading it became clear that the understandings of the commercial world could easily be applied to the residential world.

Why Wolf? I think, looking back, that there were three reasons (in late 2007):

• Made in USA
• Answers their phone (and provides fan curves)
• Hood and external blower compatibility*

(*A kitchen reno can be a gigantic systems engineering project, particularly if one is also employed. It may not reach the complexity of an F35, but it has myriad issues that need to be decided, many of which are entangled in other issues. At that time I did not want to deal with an incompatible hood and blower that I would have to adapt with extra work.)

Hoods are as "powerful" as you want to make them, assuming you use an external or in-line blower, but practicality leads to a somewhat scaled "power" with hood size, and performance leads to a standardized range of hood entry aperture air velocity values.

My hood has to encompass the cooking plumes from a 36-inch induction cooktop and a nearby 3500W Cooktek induction wok hob. The largest Wolf Pro Island hood met this size requirement. With a 1500 CFM rated (at zero static pressure) blower on the roof, I felt that it could meet the velocity goal of 90 ft/min at the hood aperture given an estimate of MUA performance. I have not yet performed a gridded sampling of the air flow across the hood aperture, but preliminary tests with a hot wire anemometer suggest the average will exceed 90 ft/min.

Quiet comes from planting the blower on the roof and using a Fantech silencer in between. Mostly I get baffle hiss. I did dampen the ducting with automotive sound dampening panels to suppress motor induced vibration propagation.

Easy to clean would require having staff do it, but I are the staff. It is reasonable to clean. Usually (which is also rarely, I admit) I soak the baffle assemblies (I have 10) in a Simple Green dosed water bath and then run them in the dishwasher (at least two loads). During that process I reach up into the cavity and clean whatever I can reach. For seriously hardened grease, two passes in the dishwasher may be required, depending on one's finickiness.

You are welcome.

Ok so thanks for making me do math, kaseki, jeez! Hooookay, so.. I come up w/810 CFM and 1215 blower capacity.

I can't do the math without the hood parameters. You seem to have selected a hood with an entry aperture of 810/90 = 9 square feet. This seems large for a 30-inch range. Would you please provide the sizing you think you will be using.

36" hood over 30" range

Thank you kaseki ! you are amazing! reading your posts just like ready a book...Ok, you are right, perhaps i need to start a new thread:)

Missi (4b IA): What is the front-to-back distance of the bottom entry aperture of the hood you have in mind?

Note: a 36 inch wide hood aperture with 24 inches front to back of opening has an area of 3 x 2 square feet. Six square feet times 90 ft/min yields a flow rate of 540 CFM. The blower should then be sized for 810 CFM. Call it 800, and this is nominal.

I have no idea front to back measurements-I just guessed a 36" hood was 36"x36", which is where I got the numbers. I've looked at a few online, but was just looking at 36" and then trying to narrow it down to stainless and then guessed on CFM. I've never seen a hood like that other than pictures or at Menards etc in their kitchen displays, so I know basically nothing other than what I've read on Houzz. The box stores are all an hour away, and we've not been going unless it's an absolute necessary in and out trip, haven't taken the time to look at them when we've gone. Well.., I take that back- I tried several days ago, but a worker kept interrupting me when I was explaining to my husband why I wanted one like that instead of a cabinet one. (no uppers, for one...soooo I don't know so much about putting the kind that goes into a cabinet up, w/no cabinet) So that's why I started the thread. Flying blind mostly. We'd be waaaaay farther behind if I wasn't stuck at home now, w/more time to research things and ask questions.

OK, unless one is going commercial hood style, front-to-back distance will be that which overlaps the cooking area and/or fits in with cabinets and peoples' desires, style-wise. I go for functionality, so I would want at least 24 inches. This may not work for you, and you may need to settle on 20 inches or a bit more. Cost is always a criterion as well as functionality and aesthetics. AJ Madison lists [many] hoods that you can scan the parameters of to get an idea of standard sizes.

Have not heard of AJ Madison, so will check it out, thank you.

Might check out local appliance shops and distributors for demos and discontinued units. I got a dual-fan VentaHood (previously mounted, powered on, but never used to vent a cook top) from a distributor as it was obsolete and discontinued (incandescent cooking lights instead of fixed LEDs). My cook top was also against an inside wall so I had to vent out through the attic. Fortunately the roof had tiles the same size as the VentaHood roof jack so all that was required was to take out a tile, pop in the jack, and cut a hole through the membrane.

It's good enough that I can cook Cajun blackened food.

FWIW, the house came with a Faber downdraft (still in place). It's quite powerful but unfortunately the rise is low and even at the lowest fan setting, it sucks the gas flames towards the inlets so you get hot spots.