You could get a plain SS hood, with baffles. I got one of those for our last home. Look up Sheet Metal Shops that fabricate for restaurants - commercial HVAC should know who does this.

I got some exterior porch lights (that had the glass jar that screwed on) for lighting (on a dimmer) and an exterior exhauser (with a damper), and a variable speed motor control.

If the exterior of the hood is to be covered by stone, then the appropriate choice is an insert. Otherwise, you are paying for external brushed stainless steel that no one will see that has been assembled with visually perfect welds no one will appreciate.

Whether the blower is from the same source or not depends on how facile you are with wiring and control selection. You may find it more convenient to use a blower that has been determined to be compatible with the control supplied with the hood.

For lowest noise, the in-line silencer and exterior blower scheme are best. However, when exhausting through an external wall, the only approach I can think of for having one's cake and eating it too is to build an exterior chase with the blower on top and the silencer inside. Means of access to the ducting will have to be designed in, but the project is simpler than certain built-in fireplace assemblies with concentric chimney sheet metal sections.

(Congratulations to Best for specifying the actual flow rate of the 1200 CFM blower when in the hood, although this will only apply to a hood with no ducting and MUA that is pressure lossless.}

The insert at the link has a moderately high sones value at full speed. While probably not intolerable, one might want to see that hood demo'd to determine whether it has some frequency component that is annoying, or emits mostly broadband white noise.

Last, I haven't got a char broiler, and thus haven't given much thought to the specific flow rate that should be allocated to it. Greenheck calls for a flow velocity of 150 ft/min -- significantly higher than the 85 ft/min (I usually suggest 90) that they suggest for successful containment for lesser heat-load cooking activities.

For char broiling, a 48 x 24-inch aperture calls for 8 square feet x 150 ft/min or 1200 CFM realized flow rate. This requires a higher flow rate blower than 1200 CFM. It may be necessary, depending on MUA approach, to go larger than the nominal 1500 CFM low profile rooftop blower, which may result in the necessity of selecting an up-blast type blower (albeit a modest one smaller than seen on restaurant roofs). These need not be on a roof; they can be mounted perpendicular to a wall. They may be quieter than direct drive blowers mounted in a hood due to their drive design.

kas

As an engineer (not an HVAC engineer by any means) - I'm suspicious of Kaseki - how many lengthly posts can he write? IMO get your own experts where you live. This guy doesn't seem to have anything else to do. May be a loser? I'm not saying, just a hunch.

Geoffrey - that is resourceful of you, thanks for the idea.

Kas - as always, I appreciate your taking the time for such a detailed response.

You are correct, our conclusion was the only way to implement rooftop exhaust would be to build a dedicated chase.

Is there any adjustment for the size of the char broiler relative to aperture - i.e. the calculation (8 x 150) for needed cfm would seem to be the same whether one had 48" of continuous char broiler vs 12" char broiler plus 36" of burners? Am I interpreting that correctly?

I've got no problem going to 1500 cfm, but it seems that there are no internal blower options that are that size, all maxing out at 1200.

Thanks

@pauls234: I don't know how much you use a grill? Are you opening a restaurant? 1200 CFM is a lot. We have a 48" range with a grill. Maybe use the grill 25 times a year.

I would reiterate that I (and many others) are appreciative Kaseki's contributions over the years. Even if he is not local to me.

Now that is an all around hall of fame response, Kas.

My choices seem to be:

-Live with a bit less than nominally ideal flow rate

-Drop the grill and go with a griddle (don't need 8 burners)

-Build a chase and go full rooftop and silencer set up

I do not know how much or how I will use the grill - I would not expect to be cooking burgers and blackened chicken regularly - more like vegetables or a quick sear now and then. Grilling for a crowd or with smokier items will be done outside.

Currently I have a 6 burner range top with a tiny recirculating mesh filtered hood that hardly covers the center whose primary function seems to be accelerating the spread of smoke throughout the house - I am acutely aware of the impacts of poor ventilation, but recognize that a well put together 1200 CFM system will be more than enough for the vast majority of situations I will be in.

I am leaning towards choice #1.

Kas - how to evaluate the trade off of capture area and needed flow rate? If I were to go with a 54", which also contains a 1200 cfm blower, the needed flow rate becomes 1350 (sticking with 150 for comparison sake 150 X 9 sq ft = 1350) rather than 1200.

Here is the 54" version:

http://www.abt.com/product/76143/Best-54-Stainless-Steel-1200-CFM-Built-In-Range-Hood-With-Blower-System-CP57IQT542SB.html

Perhaps starting with the actual cooking may help. I would expect vegetables to not need the 150 ft/min requirement because they are water loaded and will not get hot enough to generate the higher velocity rising effluent unless truly chared into glowing.

In the view of some, it is possible to get a respectable steak by using a grilling pan (cast iron with internal grid) to sear, and an oven to bake to the desired degree of done-ness. This does not require more than 90 ft/min ventilation in my experience. I think lamb chops can be treated similarly if not broiled in an oven.

(An oven under a cooktop has a chance of smoke capture and containment, at least partially, but a wall oven's effluent from broiling can only be cleared over time by whatever exhaust schemes are present. I mention this because it bears on the necessity -- or not -- for perfect cooktop ventilation. Wall ovens are a weak link in a no grease, no odor chain.)

I suspect, but have no experience with it, that one could grill or char broil at a smoke rate lower than assumed for a commercial kitchen, and thereby control any tendency for smoke spillage from a hood operating at 90 ft/min.

As the hood aperture grows, the total flow rate has to increase in proportion to the area to keep the velocity up. Either the blower has to grow or the flow velocity "requirement" has to be reduced. Care must be taken to actually discover what the entrance aperture size is. The linked hood is well under 9 square feet aperture as its front-to-back aperture distance might effectively be only 18 inches.

In any case, best capture occurs not only with enough hood side-to-side "length", but also enough front-to-back distance. Your earlier comment about hitting your head can be ameliorated by setting the hood high enough. This, of course, calls for additional size for good capture because the cooking plumes expand as they rise.

One conceptual error needs to be pointed out. Whether one is designing to 90 ft/min, or to 150 ft/min, the product of this number and the aperture area is the required actual flow rate. The blower has to be rated higher, and how much higher depends on a litany of possible pressure losses. For example, while the baffles alone may only reduce the linked hood with its blowers to 1100 CFM (there is a typo at the link so I'm not sure what is being claimed), MUA can have a significant effect unless your plan is for multiple open windows without screens. I would argue that the required CFM value has to be multiplied by at least 1.2X to find the rated CFM with even the best practical MUA system. 1.5X is more typical of realized approaches.

Frankly, I think achieving 150 ft/min actual is too far a reach unless significant funds are to be allocated for the insert, its covering, and for the MUA system (which has to flow just as much), along with sufficient hood and MUA installation space. And unless you live in a quasi tropical climate, the MUA will need to be heated. And at that flow rate it should be filtered, so it has to be actively powered. If you haven't downloaded it yet, please review the guide at this link for insight into what you are trying to approximate in a residential setting.

http://www.greenheck.com/media/pdf/otherinfo/KVSApplDesign_catalog.pdf

It is worth keeping in mind that at some level if one intends to cook like a pro on pro equipment, one has to ventilate like a pro.

The above probably hasn't answered your question of how to do trades between options, their performances (flow rate and noise), and their costs. While systems engineering has developed processes for system selection including use of trade analysis, these methods are either too formal for anyone to tolerate unless being paid to do them or are susceptible to yielding whatever answer one wants.

I would suggest instead trying to set limits (boundary conditions) on costs and performance and space and complexity and perhaps also aesthetics, and then see what options are still viable. A list of pros and cons for options may help. But getting into trade-space weighting factors and the scoring approach for each factor is likely to be less helpful than one might naively hope.

kas

All of that noted, and factored in to my next steps.

You are correct about cooking - the char broiler will not be a regular use item, but was chosen because I will find it more useful than 2 more burners and I can create a griddle with an overlay.

Thank you.

I am looking at these two hood inserts:

Best: (~$2400)

http://www.abt.com/product/76143/Best-54-Stainless-Steel-1200-CFM-Built-In-Range-Hood-With-Blower-System-CP57IQT542SB.html

Zephyr: ($~1500)

http://www.abt.com/product/80856/Zephyr-54-Monsoon-II-OPL-Stainless-Steel-One-Piece-Hood-Liner-AK9352AS.html

I am trying to figure out what the extra $1000 with the Best gives me as both are similar in size and offer 1200 cfm blowers - the only substantial difference I note is the IQ/GPS blower system in the Best (a similar 48" Best linked in an earlier post is more in the $1500 range and does not contain the IQ/blower system).

The claims of the IQ system strike me as dubious and certainly not worth another $1000, but no other difference jumps out at me when looking at the manuals.

Either one is less than what I budgeted for my initial plan of rooftop blower and silencer so I was about to go with the Best, but that IQ system just seems like another electronic board to go bad with little upside.

Am I missing anything?

I think most of us could live without the IQ system; is there a version of this insert without it? Is there a difference in steel gauge between the two candidate hoods? How much do you crave handles on the baffle assemblies?

I generally don't comment on specific manufacturers' offerings unless I have owned them (a set limited to one) or they have an obvious deficiency in capture shape.

I was able to listen to a number of these range hoods (Best, Zephyr, Thermador, Wolf, etc.) at Pirch. They were not hooked up to any ducting, so I figure that at least put them on even ground with each other for noise assessment.

They all felt well built, were all loud at full blast and all had nice lighting. I got the sense that the market for large higher end hoods with 1200 CFM internal blowers, with baffle filters are pretty well commoditized - particularly when one ignores aesthetics as this will be out of sight.

I am going with the Zephyr II Monsoon at ~$1500.

Thanks for all the help, my appliance selection is now complete and demo starts in 3 weeks!

kaseki

Kaseki, I think I remember you owning a wolf "professional" hood. What is your thoughts about your own hood and what made you choose said hood.

We will be using a 42" wide and 18" tall hood over our soon to be installed 36" wide Wolf Range top...a newer version with the higher BTUs and also has a griddle.

I am tall and hope to place the hood 36" above the top of the range to avoid head trauma. This is of great concern as we are thinking 27" deep version. Are there other hoods that you would consider or is the Wolf the best? We don't like the vent-a hoods and want infinitely variable blower control.

We are planning on an in-line blower with "muffler" at the 1100 cfm level or above. Goal is excellent ventilation system capable of removing all of those toxins, smoke & steam you have so eloquently written about over the years.....thanks for that, by the way.

Need suggestions for the roof cap...we are blessed to live in west Michigan in the lake effect area...thus, snow is an issue.

This is our first post!!

Geoffrey_b

I don't know anything personal about Kaseki. He could be a 90 yr old retired guy with nothing to do or a woman but hey, he has a lot of information and is willing to spend his time to pass it on to us without any returns for himself.. Anyone can take the info and do with it whatever. My experience with local people who want to sell you something is often they really don't know much about anything. They just want to make a sale period. That goes from Real Estate Agents to Home Inspectors on thru every profession; most of them really don't know the ins and outs and are only looking for the sale; that's when they get paid. So I find fault with your perception of Kaseki.

For our major remodel in our Florida house in 2000 I did what I thought was a lot of research and ended up buying a Venta Hood system. It seemed to work well as there was no grease on the return vent high up above the rangetop. The cleaning of the ventilation system was a real PITA and while I was cooking, it was impossible to talk to anyone (sometimes a blessing in disguise as I like to cook alone) However, if there is something better out there I would definitely be interested. I would hope things are more advanced. I'm hoping to buy a BS Rangetop which will require the right kind of v entilation.

I read all of Kaseki's posts and recently referred to copying his "tirades" (i meant in a favorable way). I read them, study them and have to admit, I'm an artist and reading his stuff often gives me a headache. We are selling the Florida Homestead and will be doing a major kitchen remodel in the house we purchased. I hope Kaseki will still be around and willing to spend his time to give his opinion which despite your opinion I and many value. I hope I will have better ventilation or at least quieter and Kaseki will gi ve me his opinion whether it will be adequate. I'm in the planning stages and we have specific problems in what we can and cannot do living in this desert community as to blowers on the roof etc. All roofs have to have parapets and vents need to me minimal and sort of not visible. Lots of rules which makes it that more difficult.

Best wishes

Inga

Ehh, sonny? Thanks Inga.

I'm back at this thread because my email shows that adamcatum evidently asked me a question in this thread before ifoco's message above. But adamcatum's message doesn't show up here now. I suppose he could have deleted it, but if you are reading this adamcatum, please ask your question again because what I get in the heads-up email is only a truncated part of your message.

kas

Sorry if I buggered up the thread.

Inga

That shouldn't happen. If it did the fault has to be on Houzz's server software.

I've never attempted to use 'edit' to delete the content of a message after it was submitted, so I don't know if complete deletion of content works to completely remove the message. If it does, then it is possible adamcatum deleted his message and you and Houzz are off the hook, Inga.

Wow!!! adamcatum's post has finally appeared where it should have been. I must have jumped into a parallel Schrödinger quantum state Houzz; I'll blame tripping on the imaginary time axis.

To answer his question, perhaps, I had a planned peninsula configuration with both a 36-inch induction cooktop and a Cooktek induction wok. With appropriate spacing between cooking units, and in concert with useful cabinet dimensions, this called for a relatively long and wide island-type hood. Further, the hood had to be aesthetically tolerable, given its massiveness and visual intrusion between two rooms now opened up into one. Last, due to the amount of time I could allocate to a "kitchen" renovation that had tentacles into many other parts of the house, plus doing all of the electrical work while also employed, I couldn't get involved in a design effort with a custom hood design shop.

Wolf's largest Pro Island hood fit the bill and had a chimney extension that allowed a height above the cooktop counter of 34.5 inches in the finished room, just enough to clear me. There was an appropriate (Wolf by Broan) roof blower available with a fan curve that suggested adequate flow rate (and resulting hood intake aperture velocity) at the expected pressure losses and MUA conditions I would eventually have.

The hood works well. Capture and containment of searing steak plumes or wok effluent is nearly total. This morning there was a delay getting the blower to move air due perhaps to household humidity (I keep it at 40% in the winter) condensing and freezing up something in the duct path, or due to some roof snow melting and refreezing near the external damper. There is still a lot of roof snow here in NH, although the blower areas look clear from the ground. Anyway, after a couple of minutes the issue resolved itself and full flow was achieved.

There are at least several other manufacturers of hoods that one can find, such as ModernAire, Handcrafted Metal, Inc., Abbaka, Prestige, maybe CaptiveAire, Greenheck; searching on the Internet can be useful for seeing the vast scope of possibilities.

As I didn't need a separate roof cap because it was part of the Wolf blower assembly, I never expended any time looking into roof cap sources so I can't help there. The Wolf blower electrically interfaces with the Wolf hood, so I didn't have to get involved with interface issues.

If I were doing it over and didn't have anything else to do with my time, I would consider adapting a commercial pedestal-mounted up-blast roof blower, nominally oversized for the application but running a belt sheaf ratio that lowered the blade speed to achieve (only!) 1500 CFM in free air. This would be even quieter (I think), but certainly a more obvious blower than the usual Wolf, Broan, and Abbaka roof-hugging devices.

In your case, you could fight the snow by using a pedestal mount high enough for the snow depth, upon which a down-blast blower assembly (sans fan and motor) was mounted. (These vaguely resemble mushrooms.) You would need an internal damper to supplement that of the hood. Other chimney type schemes come to mind, but I think searching would be best for you to cover the bases.

kas

kaseki

Thanks Kaseki for finding my message and your reply. Here is a message I wrote elsewhere and wanted you to see it too:

We would like the least amount of grease and odors in the house. We eventually will replace the furnace with a high tech. filtering/air cleaning system. There are folks with asthma living here. We cook a variety of food, including searing meat, stir fry and Indian food (strong spice smell, cooked in a Tagine). The Indian food is only a monthly or so item.

When we moved into this house, it was apparent that they really did not use an adequate vent...smelly cabinets, discolored walls and ceiling. We have removed all the flooring (now newly sanded & finished hardwood throughout), all the cabinets, have opened up walls (with pocket doors installed for closure if needed). there is all new lighting (cans) throughout and all new paint. Even the doors have been removed and replaced with new. We already have MUA installed.

We have gas heat, gas water heater and gas clothes dryer. There are 2 fireplaces...we only use one and burn wood now (infrequently)...it will soon be changed to a gas fireplace. In addition, there is currently an electric grill with a down draft vent...this is connected to its own chimney (making 3 chimney connected together and venting on the roof (one for each fireplace and one for the grill). We will be replacing the current electric grill with a wolf electric grill and will be connecting an above the grill hood which will also be connected to the current chimney. I do not know how much we will use this grill, however, 1/2 of the year the weather does not permit outdoor grilling.

Before we spend the money for a Wolf wall professional hood, we want to make sure it is going to work for us.

I have been reading about ventilations extensively through out the past months (the most research for anything we are placing in our "new" aging-in-place home). So I am thinking that the deeper & wider hood of Wolf professional wall hood (42" wide, 27" deep, 18" tall) with a inline 1100 cfm with "muffler" with a short run and two 90 degree turns (needed to get to a higher area of the attic to accommodate the blower & muffler) will do the trick. I like going with a local dealer with excellent service/white glove installation, as I am not so knowledgeable about these systems....and this hood is the only one we have seen so far that we like.

What do you think?

I can only assume that you have determined that the 42-inch hood is wide enough to over spread your selected cooking appliance. You didn't specify its size. Is this hood only for the grill?

An earlier message in this thread addresses the relative importance of 90 CFM/sq. ft., vs. 150 for hot cooking vs. grilling. (See the Greenheck reference.) For the 90 CFM/sq. ft. design point, if you have an effective* hood entrance aperture of 42 by 27 inches, the aperture area is 7.9 sq. ft., calling for a flow rate of around 700 CFM actual for which an 1100 CFM rated blower is surely adequate (for near zero house negative pressure).

However, a serious level of grill cooking effluent along with the large amount of combustion products rising from below the grill might call for a higher specific CFM level toward the 150 CFM/sq. ft. value, and this would in turn demand a blower rated at 1800 CFM, higher than Wolf supplies, although Fantech can rise to the occasion, I'm sure, for in-line blowers.

My sense is that 1800 rated CFM would be overkill for non commercial grilling. We only grill with a grooved cast iron pan over induction, so our containment requirement is easily met with 90 CFM/sq. ft.; the point where a gas grill would overwhelm our hood system is unknown.

Also, don't forget that complete capture and containment is difficult. Some effluent will expand beyond the hood, at least theoretically. Also, the plumes will not rise as theoretically expected if there are cross drafts or air disturbances by moving cooks.

kas

______________

*This weaselly use of effective relates to how the front light bar affects the flow for a Wolf wall hood and what any side cabinets might be accomplishing in flow channeling. The intent is to get the flow velocity to 90 ft/min at the Wolf baffle space, or 3 ft/s in the baffle gaps, and generally hoods have smaller interior dimensions than exterior dimensions at their bases.