I am chiming in a plea for help on the same subject. Not wanting to hijack your thread so I wont put out my "needs and wants' list, but will be interested in answers that you get. I, also, am stunned at the costs of these things - mainly the great span of cost - from pretty darn cheap to as much as you want to spend. Then there is the 'sones, CFMs, need for code requirements (or not?), ducting verses non ducting, liners (or not?), etc, so forth and so on. I have researched and looked and am more confused than ever. I just want a really pretty chimney range hood for my kitchen and not have to sell the stove to buy it! Hope we will get some answers from some folks with practical experience and real knowledge! :)

Many hoods do include the blower - they're called internal blowers - Kobe definitely includes them, at least in some of their models. Hood liners don't include the blowers - that gives you the option of an inline blower or an external blower. People get inline or external blowers in an attempt to reduce hood noise although most hood noise is caused by the airflow, not the motor. In any case, there are MANY hoods that do include intermal blowers.

My limited experience tells me that "most hood noise is caused by the airflow" only when the highest amount of air is being pulled through the hood and ducting.

Anything lower than the highest setting is likely to be quiet or very quiet when you have a remote blower, inline or external.

The blower is a motor. It causes turbulence. Better to have this far away from your ears. It may be harder to sell. Harder to install. Better to have.

There have been several discussions about hood choices in just the last couple of week so you guys might want to use the search function and read up on those. I say this not to be an a** but as a friendly suggestion since some people who regularly read and contribute here may get tired of answering the questions and simply not reply.

That said, I'll try to recap some of the general concepts and suggestions. Vent systems generally consist of four components: hood, filter, blower, ducts. Ducts are self explanatory so I will simply say to make sure they are sized correctly to the blower and possibly filter/insert. The remaining three elements can be purchases separately or together. In some cases, like Vent-a-Hood, they must be purchased together since it's an integral system by design. I'll go over each of the three parts as an overview since there seems to be some confusion.

Blowers can be internal, inline, or remote. Internal blowers are blowers that are built into the hood and filter unit or in some cases into a filter insert that can be used with a custom hood. In general the most cost effective solution is to buy an internal blower in a combined hood/filter/blower system. This is typically cheaper from both a component and installation cost standpoint. My "cheaper" statement must be qualified with: "with the exception of Vent-a-Hood". Vent-a-Hood is a patented design that they charge a pretty steep premium for. As a general rule of thumb, the amount of cfm you'll need is 1 cfm for every 100BTU/hr which means for 100k BTU/hr total power, you'll need 1k cfm. This measure largely depends on the type of cooking you typically do and the shape/size of hood. It can also depend on placement, e.g. island placement would require higher cfm to be as effective. The differences between inline, remote, or internal is basically one of installation condition and noise. Internal blowers obviously generate more noise in the living space but the perceptual affect is arguable.

The hood is the part you see. It typically provides a volume of space to capture smoke so that it can be pulled out by the blower, through the filter. The purpose is containment. Standard recommendation is to overhang the hood about 3" left and right (also front and back for island install) if possible. That means the hood will be 6" larger total than the size of your range. This is often ignored by sales people because they know that most buyers have heartburn over the hood price. A lot of this depends on if you stirfry, pan fry, saute, or deep fry a lot. Also if you have a grill on the rangetop. If you don't do any of these regularly then you can probably get a hood the same size as your range provided it's a standard wall location with cabinets on both sides.

The filter (also called "inserts") is the part that goes inside the hood. There are basically three types of filters: baffles, mesh, and centrifugal. Baffles is probably the most common for high end home and commercial restaurant use. It's not patented so most manufacturers have baffle filters. Mesh filters use to be standard for home hoods but they aren't popular today due to the fact that they decrease efficiency very drastically if not cleaned very regularly. Also, buildup will eventually require the mesh to be replaced. Both mesh and baffles operate by providing a surface for vapors to condense on. The difference is baffles provide solid surfaces that grease can drip off of into a capture container where a mesh filter holds onto it in the same space the air flows through. The third is what Vent-a-Hood uses which is basically to spin the grease to the inside of a housing. The housing holds the grease and needs to be removed to be cleaned. I've used all three and prefer baffles.

To summarize the possible combos:
1. hood, filter, and blower all separate
2. hood/filter unit with separate blower
3. filter insert with internal blower as one unit (typically used with custom or built-in hoods)
4. All three together.

Most hoods come with a filter or both filter and blower. I'm surprised you have not found any single units with all three since most major manufacturers offer single unit solutions. Internal blowers tend to be around the 600-900 cfm range. At 1200cfm, choices tend to lean towards inline or remote blowers. It does not sound like you are interested in a custom hood or super high 1200+ cfm so a single combined unit is probably your best bet to stay in budget.

Without knowing the type of cooking you do, it's hard to know how much venting power you'll need but I'd say at least 600cfm with either a 36" or 42" with an internal blower. If you've got the room, I'd go with the 42" since it's not that much more. If you regularly stirfry or saute, I'd suggest 900-1000cfm in a 42" hood. As I said before, I prefer baffle filters.

Good luck.. hope this helps.

Thanks for the responses and info! I guess I haven't seen the package deals b/c I've been looking at 1000 CFMs or greater, since the range is 100k BTUs, and they all seem to be separate components.

Our appliance salesman suggested BestK260A36SS w/ 1200 CFM remote blower, or Independent INCL36SS w/ 1000CFM remote blower. Both of those are in the $2k range. I will do some more searching for the internal blowers, maybe in the 900-1000CFM range. I have learned from this site that it's better to have too many CFMs than not enough, so I am wary of going under 1000. I think I can deal with the noise if I can find a hood w/ internal blower closer to $1k than the $2k.

If you go over 600 CFMs, you may need make-up air which can get very expensive - this is needed to compensate for air being sucked out by the hood and is often required by code - in some northern states you need makeup air for anything over 300 CFMs. Lack of makeup air in a tight house can cause furnaces to backdraft.

With a 36" rangetop without a grill, 600 CFMs is probably adequate - you're not going to have all six burners going full blast at one time are you?

weissman: excuse my ignorance but what is 'makeup air'? we're getting a kobe 800 cfm hood (it's sitting in my basement waiting for installation) and a 30" bluestar rnb.

Make-up air is a system that let's fresh air into the house while you're running your hood. With an old leaky house there generally isn't a problem but with a newer tight house you can suck the air out which can cause negative pressure and cause things like your furnace to backdraft. In some systems you can have the air intake heated so you're not bringing in cold air in the winter. Some people solve the problem by opening a window.

weissman: excuse my ignorance but what is 'makeup air'? we're getting a kobe 800 cfm hood (it's sitting in my basement waiting for installation) and a 30" bluestar rnb.

I did ask our GC about makeup air, but he said it won't be required for us. We live in SC with mild climate, in drafty house built in 1940's and we also have two windows in kitchen that can be opened. Hope that he knows what he is talking about.

So even with 100k BTUs we'd be ok with only 600CFMs, b/c we have no grill/griddle? I will shop around at those levels too. Thanks for the information again!

sorry for my dorky post above...it was late and my brain stopped working. i emailed my gc and he wrote that we were fine...a drafty 1925's house (although the kitchen will now be very well put-together since we're gutting it and actually getting (gasp) insulation on the exterior walls!)

>>>So even with 100k BTUs we'd be ok with only 600CFMs, b/c we have no grill/griddle?

Most likely yes - the rule of thumb that says you need 1000CFM is just that a rule of thumb designed to sell more powerful hoods :-). As I said above, most likely you won't be using all six burners on full blast - that's what the rule of thumb implies. I read an article a while back about how CFMs are being oversold and that many people buy more than they need. IMHO even more important than CFMs is capture area and I feel that the depth of the hood is even more important than the width particularly if the hood is surrounded by cabintets on either side.

Posted a similar question on the other current hood thread, but maybe it is better suited here...

how do you determine the amount of CFMs necessary for an induction cooktop which does not come in BTUs?

And re: filters...how do you know if they are baffle filters?

Many Thanks!
CO

There are two kinds of filters - baffles and mesh filters. The description of the hood should clearly state what type of filter it has.

Induction will produce less heat than gas but just as much smoke, steam, grease and odor so you'll still need a good hood. My rule of thumb is that usually 600 CFMs will be sufficient for most people unless you have a grill. Just make sure you get a sufficiently deep hood - at least 24" deep if possible.

We are looking at 24" depth, and I think we will go with 36" width although we did put a call in to our cabinet maker today to see if we have room for a 42" width based on the suggestions from this thread. Regardless, there will be upper cabinets on either side of the hood, which I guess helps with capture? So, with 24" depth and at least 36" width, sounds like we will be safe with 600CFMs. Thanks for the input everyone - I feel much more confident about ordering a hood now!

To the OPs original question: I believe Broan/Nutone is the owner of the Best line. Broan supplies fan curves at their website, which helps estimate performance loss with pressure loss. Broan fans are used by Wolf, last I heard. I don't know about the blowers made by the others, but they are well enough known to likely use fans appriate for their hood designs. The issue is whether the hood design is appropriate for the intended use.

I've addressed this before, but given the variability of the search engine at this site, I don't mind repeating it.

As noted above, the purpose of kitchen ventilation is capture and containment. Capture means getting the effluent into the hood, containment means moving it somewhere else. If the flow velocity in the hood is too small, it is possible to capture but not contain as the effluent will curl back out of the hood. Effluent rising past the hood is generally not captured by the hood and spreads through the house.

The hood, for any likely fan capability any of us would use, does not suck up effluent from the stove top, or pull it in from the side away from the hood, except in the sense that all the house air will eventually be pulled out through the hood if it runs long enough.

There are many rules of thumb, and some of them, such as at Greenheck's site, depend on what's cookin'.

What you want to do is have the hood extend beyond a conical area starting at the edges of the pans and extending to the hood height. The effluent expands at various angles for various cases, but generally in the 20 - 25 degree range, half angle.

Once the effluent is in the hood, containment requires that at some point before the effluent bounces back out, it meet air flow at the effluent up velocity, around three feet per second. It is this velocity, multiplied by the area where this flow is most critical, that the hood blower has to achieve. Pitched roof like hoods, such as commercial hoods and residential baffle hoods, gain effectiveness by drawing the effluent to a narrower baffle area where a given flow yields a higher velocity. Flat screen hoods, on the other hand, need more air flow relative to their outer dimensions or the effluent escapes.

Once the cfm are established by the above approach, the duct size is selected to ensure that when cooking is fierce and the blower on maximum, the duct velocity be in the range of 1000 to 2000 ft/minute.

Next, the fan/blower has to be sized to achieve the specified cfm. This can be a complicated process if done in detail. I suggest that given typical duct lengths, filter resistance, transition pressure losses, and restrictions in make-up air, the rated cfm of the blower (which is measured with NO pressure loss) be around 1.5 times the specified cfm that was determined from air velocity and containment area.

The requirements for modest cooking efforts will allow the hood blower to run at a reduced speed, so blowers should be selected that work with a variable motor control. Noise level will be a lot lower.

kas

I have a Kobe wall hood and like it very much. Almost 2 yrs old, no problems. Quite quiet for the power, I almost never need to run it past the second (out of four) power setting, and it has a 'quiet' setting as well. A lot of hood for the money.

FWIW, I recently installed an Imperial 42" island hood with twin blowers (about 1300cfm) over my BS 6 burner rangetop.

I checked out several different hood brands and chose Imperial because of high power-low noise, quality construction and excellent customer service.

I called Imperial with a problem and they could not have been more responsive and supportive. I'm demanding and not easily impressed and believe me, I was very impressed with their service. I was assisted by an exceptional guy named Oscar.

Hoods and ventilation are somewhat complex and it is easy to make the wrong choice, so do your homework. I researched and spoke with several sellers and had the best experience with a salesperson named Donald at vent4less.com. He was honest and patient with me and more than delivered on everything he promised.

Anyway, my hood is working great, is powerful and is not too loud.

Hope this helps and the best of luck to you.

Most likely yes - the rule of thumb that says you need 1000CFM is just that a rule of thumb designed to sell more powerful hoods :-). As I said above, most likely you won't be using all six burners on full blast - that's what the rule of thumb implies. I read an article a while back about how CFMs are being oversold and that many people buy more than they need.

So this implies one should buy a blower that is good 95% of the time but not the 5% of the time when the ovens are going and all or most of the burners are going? Likely when the home is full of people such as the holidays or parties? Renovate a kitchen and take it to the two yard line?

The manufacturer's vent recommendation for my 36" DCS AG range (6 burners, 93K Btu total) was 600 cfm. My HVAC guy wouldn't do any less, but also told me not to even think of anything more. The cost of my 600 cfm VentaHood, including installation of heated make-up air exceeded $10K.

Some of us have to draw the line somewhere between perfect performance and affordability!

Ourbigdig, did you make a decision about your hood yet? I am also planning on a 6 burner Bluestar. I will need an island hood, though.

I checked out the vent4less website as kelsold mentioned but I wasn't thrilled with the selection.

I looking for a very basic chimney style hood.