What is your view of affordable noise? Is the duct going to go through an attic space large enough for a silencer to be used? What is the Bluestar width? What is the pressure loss of your HVAC folks' planned MUA configuration (at, say, 800 CFM)?

I've been around a zephyr and vent-a-hood 1200 on high and they were fine noise-wise.

The attic would be large enough for a silencer / it's a pretty big space.

The MUA discussions with the HVAC are just beginning. Again, there are no reg's here (CA; mild climate) so we can do whatever we want, but want to be safe. There is no water heater or open fireplace in the square footage. We have a gas insert. House was built in '79.

I've just heard so many stories about the 24" and the fact that the bluestar (36" in our case) has the hottest burner up front (I will likely be modifying the RCS to do 21k). It just doesn't seem that searing steaks and woking would be captured if the hood is 24.

The salesperson said he sells far and away more 24" deep hoods, but told of 1 bluestar customer where he had to replace the hood due to being disappointed with the capture. Replaced it with a 27 and customer was happy.

Ideally, you would also overlap on the ends of the range. Assuming a 27 x 42 inch hood, and pretending for the moment that the aperture is that size, then the aperture would be shy of 8 square feet, and need at full power a flow rate of 700 CFM to get 90 ft/min air velocity through the aperture. With baffles, transitions, ducting, silencer, roof blower, some MUA restriction, a conservative blower rating would be 1.5X that, or a bit over 1000 CFM at zero static pressure. 1200 CFM would be fine. (Note that I am carrying decimal values but only writing rounded numbers.)

If you went with Vent-a-Hood, the blower might be adequate at a rating of 900 CFM, (not the magic lung "equivalent" rating), due to lack of baffles and silencer. VaH squirrel-cage blowers have a less robust fan curve than conventional blowers (e.g., Broan/NuTone/Wolf/etc.), however, so the roof cap should be selected for low pressure loss, as should the MUA path.

No matter what hood you choose, if you want good cooking plume capture the hood aperture should overlap the locus of all pan base edges by at least ten degrees half angle, which means that the minimum hood size should grow as the hood is raised. Note that for woks, base size is taken to be the part that is being significantly heated to smoke the oil. Design should keep the hood high enough to avoid intersecting the cook's head or blocking the view of the contents of the rear pans. Stick figure sketches can clarify head clearance on bending and visual lines of sight.

kas

thanks, kas. So, given that information, I should stick with the 27"? My appliance dealer just emailed me tonight and he's looking into a windcrest for about $1300. Technically, the bluestar RCS has all 15k burners and I will be likely modifying one..i could modify one of the rear burners instead of the front, thereby being able to use a 24"? Or is that playing with fire, so to speak...

Why would the physics indicate that a 27" is required, but nobody makes them? I'd like to hear from other people that have experience with a 24" and how that works with wok / searing, etc.

I can't answer your question because I don't know how far from the wall your front burner pan base is. (Or alternatively, what the distance is to the center of the front burner and what the pan diameter is. In this case, pan diameter is base size, not top of sides size.)

A 27-inch hood will require more air flow, and likely have to be higher up for head clearance, and perhaps manufacturers do not see a large enough market to supply them. However, certainly custom manufacturers such as ModernAire will make what you need. In any case, according to the Wolf Design Guide, Wolf makes some that size.

Adequate capture area can be had for a price [Handcrafted Metal, Inc].

There is a factor that should be recognized -- in a wall application, particularly with side cabinets, more of the air flow is pulled in from the front, partially rising from below the counter level. This will move the plume vector slightly inward and thus have the effect of virtually extending the front of the hood slightly.

So please let me know your cooking dimensions per the first paragraph and I'll look at what the angle is.

kas

Hi Kas. Awesome pic, btw...

So, i need to measure from the backsplash to the center of the front burner, correct? Then, give you the width of the base of what I would expect the widest pan we'd use on that front burner....

Affirmative.

16.5" backsplash to center of burner (+/- .25). 12" pan base, max; median of 10" most likely.

I think we are ordering this... best deal I have seen and I read they are pretty solid. Sure, Modernaire was preferred.. but way outside my budget.... wife said "8k for the stove.. OR 5k for the hood.. your choice.." lol

http://www.therangehoodstore.com/54-inch-wall-range-hood-trhs796.html

elbell19 I have a Windcrest 30"w x 27"d x 18"h 1200cfm over my Bluestar 30". Definitely a quality product and I am glad I went with the 27" deep. On my Range the 24" deep would not have been adequate to capture everything. I'm very pleased with the Windcrest hood.....

Russ, i don't see any undercabinet 27" deep there, do you? Have any direct reports on quality yet?

oops.. did not see the undercabinet part... sorry!

Great prices on range hoods though, eh?;)

R

Hard to find a 27" deep in a under cabinet design, I've been there. I opted to get rid of my upper small cabinet to accommodate my hoods 18" height. Between the 18" height and 27"deep it makes a nice big cavity for capturing everything. If this is not an option for you it's a limited selection out there .....

elbell19 wrote, in part: 16.5" backsplash to center of burner (+/- .25). 12" pan base, max;

So we would want a hood front to back distance of 16.5 + (0.5)12 + H tan 10 deg. If H equals 30 inches, this sum equals 27.8 inches, supporting the 27-inch selection.

One approach that some have done is take a smaller hood, place it away from the wall, and build a sloped surface from backsplash to rear of hood. A sheet metal shop could easily fabricate such a directing surface from stainless steel.

kas

Hi Kas. Thanks for the math. Definitely out of my league.

sounds like we might be able to get away with installing a 27" at 32" off the counter? We are also researching the bump-out. My contractor doesn't like that it isn't manufacturer approved, but he'd get over it...

Think of it as a shiny tile backsplash with poor vertical alignment. :)

There are some pre-patterned stainless steels that can look fairly pretty. Just keep the angle of tilt-out (from vertical) shallow enough that a rising expanding plume that hits it is still reflected upward. Three inches of tilt over 32 inches (less if the range has its own backspash) is easily sufficiently shallow in angle. Even a less observable short metal piece close to the hood could be built and be 30 degrees or less from vertical. For example, a six-inch piece of metal tilted out 3 inches at the top would be at 30 degrees.

Tour http://finishedkitchens.blogspot.com/p/kitchens-alphabetically.html for ideas.

In any case, a serious gas range needs some consideration of what the wall behind it is made of, and I'd start with 5/8 firecode sheetrock (or stone or brick) covered by something fire resistant, such as metal or tile. Assume a raging grease fire in your planning, because that is what the range manufacturer did to comply with UL and to specify offset distances to combustibles, and what the hood manufacturer did to comply with the hood filters performing their fire blocking function.

kas

ok, dumb question....if we decided to get a hood 'liner' and have our contractor build the box, does the box just need to be 27" and then the liner sets into the box with the actual liner depth of 22.5"? or is that cheating? Just curious...

In that case grease would get into the spaces outside the liner but inside the box.

However, this is a good idea given a couple of tweaks. Insert the liner higher in the hood box than flush with the box's base, then use sheet metal pieces to tie the bottom of the box to the bottom of the liner, taking care to keep the angles such that reflections occur upward. This, in effect, increases the hood size for little additional cost, and liners are less expensive than finished-exterior hoods. (You could, of course, order a custom liner to fit the box interior.)

Your cabinet maker can design the internal structure to accommodate this. It may help to have the insert in hand before cabinet box fabrication. Blower flow rate should be selected to achieve 90 CFM/square foot of box entry aperture at full power, as described upstream in this topic.