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RE: Range hood help for NXR 36" (Follow-Up #1)

posted by: JWVideo on 10.29.2012 at 04:06 pm in Appliances Forum

There are numbers of recent discussions of range hoods and a search will turn up a lot of helpful information. Besides recommending that you search for those threads, I'll just make a few suggestions here.

1. The reason Kobe told you that a 600 CFM hood will not be sufficient is this generally acepted rule of thumb: for high-btu stoves, figure 1 CFM of fan capacity for each 100 btu-hr capacity of the stove. If you have all six 15k BTU-hr burners running on max (90,000 BTU-hr gas consumption) AND you have the oven going as hot as it will get (20,000 BTU-hr), that totals 110,000 btu-hr of gas being burned. Do the arithmetic and you get a need for a 1120 cfm hood. If you look only at the cooktop output, your NXR still is capable of burning 90,000 BTU-hrs of gas, which translates to a 900 CFM range hood.

This rule of thumb was developed for commercial kitchens where they might very well be running, say, three woks or three saute pans at max heat while also boiling three pots of pasta water.

If you do not plan on putting on that kind of show, then a 600 or 700 CFM Kobe hood probably will work okay.

I'm using a 600 CFM hood with my 30-inch NXR which is theoretically the minimum for my four-burner stove. I have yet to overwhelm it. But, then, I do not simultaneously run all four 15k-BTU-hr burners on max, searing steaks and boiling pasta water while running the convection oven at 500 F.

2. If you already have 7-inch ducting, that can expand your choices of hoods. My recollection is that most 600 CFM hoods use 6-inch round ducts and/or 3"x10" rectangular ductings. The difficulty with going for larger hoods is that many of them require 8" or larger ducting being recommended. In theory, you can reduce down to a smaller size but it affects efficiency and tends to diminish the air-flow capacity.

3. Kobe hoods are generally pretty well thought of here at GW. (As always, do a search).

4. This leads to another rule of thumb. A big deal with rangehoods is "capture area." Units that are actual hoods (as opposed to flat-bottomed venting units) will do a better job at capturing and containing smoke, steam and other vapors. Even with canopy-type hoods, there is still a suggestion to get a hood that is the next larger width than your stove. That is, you get a 36-inch hood for a 30" stove, a 42" hood for a 36-inch stove, etc. But, if you are constrained by cabinets, then a 36" hood will have to do.

5. For an interesting example of a 700 cfm Kobe hood with a 36" NXR, check out this link, which is an article from the 2011 Fine Homebuilding annual edition on kitchens and baths.

6. Finally, a couple of related points.

(a) In the couple of months that I've had my NXR, I've found that those 15k-btu-hr burners work better in high-heat applications with larger pans (at least 10 inches in diameter and preferably 12-inches or greater). With the larger pans, there seems to be less waste heat in the kitchen (that is, the large pans do a better job of capturing more of the heat.) However, there is a trade-off: more vapors and goo come off the surface of the pan, which means that there is more of that to be collected by the range hood (and more to be cleaned off the stove.) That inevitably means that the hood needs more frequent cleaning. So, consider cleanability in your choice of hood as well as having grease traps that will minimize the amount of grease that gets past the hood to your ducting. My recollection is that Kobe hoods have a pretty good reputation in that regard.

(b) The NXR oven vents out the backsplash. It can get pretty hot back there on standard bake. Virtually any range hood can take care of that heat. It is a different story when you run the convection fan. (This is likely true of almost every gas convection stove.) Unless you enjoy hot-house temps in your kitchen, you definitely want a good range hood to help evacuate that heat.

6. There is another, subtler reason to consider a larger-capacity range hood. Lower noise. A bigger and more powerful hood can move the same amount of air at lower motor speeds. Lower motor speeds generally means less machine noise.

7. Finally, remember to check on the need for make-up air. Even a 600 CFM hood moves a pretty fair amount of air. That air has to come from somewhere in the house. Make-up air can be simple or complicated depending on your situation and you local building regulations. Numbers of cities and some states are now prescribing requirements for make-up air. In some places, it may be enough to provide direct MUA for appliances that could backdraft (say, water heaters and gas furnaces). Check into this.


clipped on: 02.08.2013 at 11:47 pm    last updated on: 02.08.2013 at 11:47 pm

RE: Range Hood Hell - Please help! (Follow-Up #13)

posted by: racmrc on 08.28.2012 at 05:42 pm in Appliances Forum

Mizzm - we have a "BEST" by Broan range hood. It is a 48" wide x 24" deep Model K260 with stainless baffles. We use an external 1200 cfm blower by BEST along with a Fantec silencer. Our duct has a length of 13' physical feet with one 45 degree and one 90 degree bend. The 48" hood was $1050 and the external blower was $780, both purchased locally where I'm located.

Sound levels are hard to describe but I'll try:

Lowest speed (this hood has variable blower speed) - on low you can't hear it

50% speed - our refrigerator running will drown out the blower but noise level of wind hiss is similar. So far it seems this will be the speed we used the most.

75% a bit louder than the refrigerator but only hear wind noise with air going thru baffles - loud enough to hear but noise drops off as soon as you back off from the hood, especially about 5 feet away. This speed so far is all we've needed when doing the most smoke producing cooking - using cast iron skillets super hot and blackening various meats. Tons of smoke and 75% power easily pulls everything out.

100% - a slight hum from the remote blower and a fair amount of hiss of air being sucked thru the baffles. Sound level probably about 3/4 way between the sound of a refrigerator running and a table top microwave (probably closer to the microwave). We haven't seen yet where this full speed has been needed - but good to know its there.

Our previous range hood had an 8 sones sound level and just for reference - 8 sones is similar (to us) as a jet engine running the the kitchen - or maybe even a lawn mower. 8 sones is very distracting and hard to have a good conversation.

We looked at many different hoods and every hood we saw with an internal blower was loud so we knew we really needed the external blower. With our kitchen remodel our kitchen will be part of a great room and we wanted the quietest possible blower setup we could get. We are 100% satisfied with the performance and noise levels.

With our remodel, we will soon have a different rangetop installed (already delivered), a 48" BS with 24" grill and we have no concerns about our range hood being able to do the job since it's already proven it can handle what we throw at it.

I would not hesitate to purchase the BEST products again - much cheaper than others and nice quality.


clipped on: 02.08.2013 at 08:42 pm    last updated on: 02.08.2013 at 08:43 pm

RE: Range Hood Hell - Please help! (Follow-Up #2)

posted by: kaseki on 08.26.2012 at 10:36 am in Appliances Forum

Unfortunately, for air flow rates lower than 5 digits the hood doesn't actually suck up the cooking effluent. The effluent rises on its own at a fairly rapid rate (3 ft/s) and expands. The part of it that impinges on the hood aperture will be captured and with enough flow rate, contained. This is why size is important in range hoods -- to overlap the rising and expanding cooking plume. Note that this overlap is relative to the size of the pan or griddle, and not in particular the overall range size. Assume a nominal 22.5-degree half angle for plume expansion (angle varies somewhat with a lot of parameters). And it is the internal aperture of the hood that matters for capture, not the external size.

When cabinets or side shields are in use, the hood need not be longer than the range, but without them the 42-inch recommendation should be heeded.

27 deep is probably essential for normal hood heights.

Turbulence from cross drafts and people moving about can cause effluent to miss the aperture even when all design rules are met.

For least noise, as Clinresga and other have documented, a remote blower with in-line sound suppressor (muffler) is the best approach. This approach will attenuate the blade tip noise and much of the upstream duct turbulence noise. Air flow turbulence noise around the baffles, however, is not avoidable. (After all, the baffles work by reversing air direction so the larger part of the grease particle size spectrum impinges on the baffles.

I have a Wolf/Broan 1500 cfm roof blower with Fantech in-line sound suppressor. At full power the sound is certainly present and marginally obtrusive, but normal conversation across the peninsula and along the peninsula is not degraded.



clipped on: 02.08.2013 at 08:38 pm    last updated on: 02.08.2013 at 08:38 pm

RE: Range Hood Hell - Please help! (Follow-Up #1)

posted by: trevorlawson on 08.25.2012 at 08:57 pm in Appliances Forum


Hood sizing for a 36" BS with CB from good to excellent is

36 x 24
42 x 24
36 x 27
42 x 27

If you increase the capture area you increases function and that would allow you to run your hood at lower speeds to reduce noise to a degree.

Quite hoods do not remove smoke and grease very well at all. In your situation I would not worry about noise, the function is far more important especially with a charbroler on the range top.

Moving air makes noise, but moving air also removes smoke and grease. A quite hood does not move much air so consequently it removes little smoke and grease. If you have a reasonable distance from your hood to the outside wall you could consider a remote blower which WILL reduce noise.

Stainless steel baffles are easy to clean no doubt about that, simply take them out and wash them in the sink or dishwasher.

1200 cfm will be needed for that range, 1400 cfm for a remote blower.

When it comes to the cost of Modernaire, you should check out that for yourself, what one man thinks is expensive another thinks is good value, especially if it only one of a very few that fits your needs.

Overall IMO you are buying a very good COOKING range, so it is vital that the hood is equally as good as its job as the range will be. What you don't want to happen is that you don't cook as you intend because your hood sucks (and i don't mean that in a good way)


clipped on: 02.08.2013 at 08:36 pm    last updated on: 02.08.2013 at 08:36 pm

RE: Big Family--Need a Gas Range Recommendation (Follow-Up #10)

posted by: JWVideo on 12.03.2012 at 01:23 am in Appliances Forum

>>>"We can move the range and vent out an exterior wall. But what range do you recommend for a large family? We do a lot of cooking and baking--three meals a day all from scratch. Should we go commerical or can we get away with a less expensive range? A repairman came recently to fix our dishwasher and told me to go with a Thermador. He said it was basic, but we would not have as many repairs with it as with a GE Cafe, which has all of the electronics that can break."<<<

I agree with laat2's comment about parameter confusion.

You seem to have ventured into the morass of high-end and pro-style appliances without the vocabulary needed to navigate these murky waters.

Let's try to get a handle on the vocabulary.

First, there are "pro-style" ranges and there are "commercial" ranges. Very different critters. Commerical stoves are what go into restaurants. No broilers in the ovens. no insulation on the sides or doors. (Bad idea with all those kids roaming around). They are set up for very large pans and continuous production cooking. You need to put them in a fire proof/resistant enclosure (generally, tile) and you need very serious ventilation systems (which will require make-up air and a fire supression system, as well. A lot more of costly than you might suspect from the prices of the stoves.

Second, Viking, Thermador, et al are not "commercial appliances." They are residential ranges. The term often applied to them is "pro-style." Pro-style is sometimes a synonym for premium-priced luxury goods. Sometimes they are called "trophy stoves" which is a terms used when people buy them for their industrial (high-end) looks.

Pro-style tends to be expensive but tend to have a more room on the cooktop than less expensive "standard" residential stoves. This is handy when you cook with several larger pans at the same time. They vary in how "basic" they are, however, particularly when it comes to oven functions.

You also say you think you want "basic" meaning something with fewer components that can break than a GE Cafe might have. (Which, by the way, might be a pretty good choice for you in a 30" wide stove with the wide cooktop space and the extra "baking" oven. There has been a fiar amount of discussion of them here over the last couple of years and search will turn up those threads.)

Apparently, your preferences inclines to stoves that do not depend on electronics and microprocessors to operate.

You do understand that there are some trade-offs in this? If you give up processor-driven electronics, you also give up some conveniences, such as self-cleaning ovens.

So, you've got a family of ten to cook for? How many people are using the stove at once? Can you really work with a 30" wide stove or are you considering something wider? AFAIK, Frigidaire is the only North American stove maker who still makes a 40" wide gas stove. Sold under its own brand as well as Kenmore, it can be had as all gas or dual fuel.

Otherwise, you will be looking at pro-style stoves in widths of 36", 48" and 60".

For the pro-style all-gas rangea, the most basic are the NXR 30" and 36" stoves ($2k and $3k repsectively at After that, you are looking at about a $500 jump to the next tier of pro-style stoves, which will be Italian imports like Bertazzone and Verona. (And, if you are in Canada, Costco Canada sells a bsic Blue Star for $2400.) Another roughly $1000 jump takes you to dealer prices for Blue Stars, American Range and Viking's D3 line as well as Kenmore's and Kitchenaid's pro-style stoves. Spend another $500 to $1000 and you are looking at Wolf ($4k) and Thermador ($4.2k) and GE Monogram (?) all-gas stoves. It goes up from there.

Viking gets slammed here because it has had quality control and warranty service issues and has had proprietary parts which get discontinued. There are long threads here on this topic.

There are long threads on each of the other brands, as well. Each of these stoves has its following here at GW and each has been very thoroughly dissected, except for American Range, which is new to the residential market.

If you want more detailed help, you could be more specific about your remodeling budget as well as about how you cook and what you cook (and how many of you need to work the stove at a time.) For example, if you regularly use three or four large pots (say, 12" diameter ones), a pro-style range my look pretty attractive. OTOH, if you are mainly cooking with one or two large pans at a time, but you do a lot of baking, then maybe you want to look at a standard range like the Frigiaire FPGF3081KF, a gas range which has third-element "true" convection in a 5 cu- ft. oven (for about $1300, but probably less expensive this holiday season.)

With regard to design, I think cj47 has given you a good suggestion for also checking out the Kitchens forum..


clipped on: 02.08.2013 at 01:10 pm    last updated on: 02.08.2013 at 01:11 pm