How to... Kitchen hood vent project

[Jim Kaczmark]

Below are a few pictures of a hood vent that I'd like to replicate for my kitchen project. I have dimensions for the hood vent insert that I'd like to use. However, I'm finding it a bit daunting to finalize my design. Looking for any tips you can provide me from those who may have designed / build something similar before. Some of my questions / concerns:

Products that I'm working around are the Wolf R366 36" gas range (all gas burners, no griddle or grill), and the Viking 42" VBCV vent hood insert.

1) How are the "solid looking" sides build / attached to the rest of the unit & adjoining cabinets. Would you make these sides from solid dimensional lumber... perhaps a box of plywood surfaced with the solid lumber? In my kitchen design I have a corner cabinet, a wall / upper cabinet, then this hood vent. Both the corner cabinet and hood vent have to be placed exactly, leaving the wall cabinet the only item with room for changes in dimension / scribing. I'm thinking of making the outside of this vent hood side notched so I could back the vent hood side up to the front of the adjoining face frame instead of scribing the side of the face frame to the side of the vent hood. Any suggestinons here?
2)Installation. What is the order of installation? Install hood first, then ducting 2nd, or just the opposide order? Perhaps a sequenced order of rough framing first (a simple 2x4 box to support the weight), followed by the adjoining wall cabinet, one side of vent hood, the vent hood insert itself (attach vent hood to the wall, and to the one side), the front panels of the hood, the other side of the hood, then the "front shelf" of the hood. Any suggestions?
3) Any comments regarding clearances / lessons learned regarding vent hoods? Clearances From Viking / Wolf state a minimum of 30" from top of counter to bottom of hood, 18" from adjoining counter top to bottom of adjoining cabinets (in this case it must mean the bottom of the solid wood sides of the vent hood), and a maximum adjoining wall cabinet depth of 13". What clearances have you used before. I understand this may be more of a local code issue, but any input will be helpful.
4) I would have loved to install deeper side cabinets than the standard 12". However, with the 13" max depth mentioned above, if I am restricted to keeping the sides of the vent hood to 13", in order to set back the fronts of the side cabinets from the front of the vent hood side, this would force me back to only 12" depth side cabinets.


http://www.sawmillcreek.org/E:\hoodvent1.jpg

http://www.sawmillcreek.org/E:\hoodvent2.jpg


Thanks in advance for you comments & suggestions.
Jim

[Greg Heppeard]

Hmmmmmmmmm don't know how to fix the little red X in the box. (no pic here)

[Jim Kaczmark]

Sorry... pictures did not post. I'll try them as attachments below:

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[Tom Godley]

Is there a reason you are looking at a wider hood than the stove top?

Just make sure you like the look of that - the unit in the picture looks to be a matching size for the stovetop. But the stovetop looks overpowered by the hood. It may look fine -- but some of the hoods can get large. Most of the custom hood I have seen are just built up of plywood and trim -- they attach to the wall/ceiling just like any other. The hoods/inserts attach to the wall - some of the larger units also require support from above - like a threaded rod.

I have a 48 inch wide DCS unit with a matching 48 inch hood (not an insert) so I had to mount it to the ceiling with rods and also to the wall. The DCS insert mounts the same way -- The viking was the same layout. They are very heavy!

The vent size is very important -- it must be large enough-- also very important to size the roof or wall outlet correctly. You need to count the 45 and 90 or you will loose CFM and increase noise. You need to have the vent in place -- then you just add a transition from the unit. If it is an outside wall you are in luck.

One thing I would do differently is to install the motor at the roof outlet - to decrease the noise - this may not be any help if the unit is on an outside wall - mine is not. I also have a grill and a griddle -- the grill really increases the CFM needed - so the noise is a thing to worry about.

One note - The 42 inch hood insert would be designed to handle more than just 6 burners of a 36 inch stove top -- so you are getting a hood that may be overkill and may produce more noise that you may like.

Follow the clearances to the letter.


My sister has a wolf five burner with the pop up rear downdraft system -- it works great and is out of the way. The big hoods are not all they are cracked up to be -- except BIG.

[Jim Kaczmark]

Thanks for your reply Tom,

Below is a Sketchup image of the kitchen I'm designing. It will show the proportions we're talking about. I agree with you, the stovetop in the image is very over powered by the hood, let alone a 42 inch over that stovetop.

I've worked with the local appliance store and have sized the cfm. They called for 900cfm. Duct run has one 90 bend, then a 20 foot straight run to the exterior wall. Home designer is making sure there is duct space in the joists above the kitchen for this run. Would have liked an external fan, but placement of it on the exterior wall would have been bad. Unfortunately, I don't think that Viking offers a 900cfm internal fan with their 42 inch hood. That may force me to the 36 inch hood. All of the above I'm going to discuss with Viking (hood mfr.) directly.

Given the size of the kitchen, we like the look of the 42, plus, I've heard that a wider hood will provide better venting with all other variables held the same. (Again, I'm going to verify this with the mfr.)

So, this post's question is more about construction than hood size / selection. If it is a 36" hood, then the construction will be the same, only smaller.

Home / kitchen scheduled to be done July 2009. Kitchen will be a big job, but should have pleanty of time to complete it.

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[Jim Kaczmark]

Another picture showing a 36" range with 42" hood. This is where we got the idea of this combination. Wife simply liked the style of the hood in the above picture better.

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[Greg Funk]

I second Tom's concern with the hood noise. When we built I listened to a lot of fans and thought anything capable of reasonable CFM was far too noisy. We ended up using a remote in-line axial fan. I believe it was made by continental (http://www.continentalfan.com/axcrange.htm). The fan speed is adjustable and we normally use it on the lowest setting.

We had the range hood insert custom made and as I recall it was a similar price to the commercial versions but much quieter.

Greg

[Norris Randall]

Here's my 2 bits worth. (2¢ after inflatiion :))
When we decided to remodel some in our kitchen we had a custom hood that was going out. (coppertone:mad:).
My wife does some china painting on tiles and this was what she wanted.
I built this hood from plywood and lined underside with plastic laminate .
The same exaust pipe was used so; just purchased new blower with aluminum filters and light.
It is louder than we would like.
Hope this is of some use to you.
I sat on the floor to shoot the pic.
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[Jim Kaczmark]

Well, looks like too many are saying the 42" hood would be inferior to the 36" in my application. Viking reiterated the same thing you and other's have said. (Contrary to earlier internet searching I did on this subject by the way.) I'll now be going with the 36" hood. I looked at the continental fan information, and that does look very promising. Will contact them tomorrow when their office opens up & ask some questions.

Back to the meat of the post. I'd love any input as to the actual (wood) construction of the hood vent. Most of my concerns were listed above.

Thank you in advance.
Jim

[Greg Funk]

One other thing - use the biggest vent pipe you can. The larger the pipe the lower the air velocity and the quieter the fan will be. Much of the noise comes froms the air rushing through the pipes.

Greg

[Ben Grunow]

I have installed many of these and the best thing you can do is cut a hole in the wall behind (if possible) to make the duct connections possible. If not the insert will have to be installed after the hood and the ducts must be just right so they can slide together. Usually the guts of the hood come out so you can guide the ducts together from the inside.

I think the 30" nuber is to any combustible materials above the cooktop and within 6" of the sides of the cooktop as well (need 48" for 36" hood)

I think most hoods are about 26" deep and set with the bottoms about 30 above the cooktop. Be sure to remember that the range top is usually about an inch or so above the counter height.

[Tom Godley]

As I said above -- The wood parts of the hood would be constructed - like any other surround would be made. Look at how a mantel is made it ends up being the same thing.

You can always add a few blocks to attach to the wall and ceiling -- the sides are attached to the wall cabinets.

My trim, fridge and stove built-in were all constructed with the same figured maple plywood that all the rest of the kitchen used.

[FRITZ STOOP]

JIM,
I really don't mean to be critical in the negative sense, but I have to agree with the "overpowering" remarks.
The workmanship is wonderful, and that shelf and support molding would make a hell of a nice mantle, as well.

[Jim O'Dell]

Tom seems to have a good handle on how to make and install the wood part of the hood. I've never done this, but it seems like it is just another piece of upper cabinet. The design and shape need to compliment the rest of the cabinetry, but it just holds the guts of the hood instead of glasses and plates. Sounds like you are a lot like me...trying to make it harder than it really is. The hardest part I see is making the angle cuts for the slope of the sides...the same on both sides!! :eek: :D Jim.

[Dave MacArthur]

Jim, good look to the hood, but can I add a huge caution to be considered in any hood design? GREASE.

The hood is intended to suck the airflow up thus grease-laden air. However, no matter how strong your fan, the size and distance from source allow a ton of oil/grease spatter to accumulate near the stove. If you put little nooks and crannies, and worst of all square dentil crenelations, they will just rapidly cake up with grease and dust, and be uncleanable.

I recommend that all your profiles be SMOOTH so that they can be easily wiped and cleaned--no carving or indentations or corners down low. Trust me, a dust and grease caked hood loses it's intricate beauty quickly!

Good luck!

[Jim Kaczmark]

Dave, I'm glad you confirmed that for me. The, as you put it "dentil crenelations" shown on the hood under the main shelf area I was planning on simply leaving off for that very reason. Construction will be simpler if I make a series of steps to bring transition to the bigger beefier shelf above them... basically the same as the picture, but without the small blocks under the shelf placed every foot or so.

[Rob Luter]

Jim - I spent 20 years engineering both commercial and residential range hoods. Anything you come up with will wind up being a compromise between aesthetics and function. As long as you are aware of that going in you’ll be ok. A couple of points:

Overhang (hood bigger than range top) is a good thing, more so the higher you are off the top of the range. I would put the 42” hood over the 36” range. In addition, I would make sure the front of the hood overhangs the front of the range too. While the look may not be your cup-o-tea, it will assure proper function. A well designed range vent system is intended to capture cooking vapors (heat, grease, steam, etc.) and pump them out of the house. The bigger the capture area is (width x depth) the better it will capture the vapors that are rising off the range top. Once they are in the hood they can be exhausted using a reasonable amount of air. If the hood is too small you need more air and you get more noise. Capture velocity of 100 fpm usually works well. That puts the CFM of a 30” deep by 42” wide hood at about 900 CFM Vaporized grease can be extracted from the airstream with filters or conveyed to the outdoors in the airstream. A little bit of both usually happens. For filters to function properly the air velocity has to be predictable. It will vary based on the filter type. The amount of resistance you’ll have in your filters will vary by type too. If you don’t want grease buildup in your duct you’ll need to maintain air velocity of about 1600 fpm (about 18 mph). That’s not as fast as it sounds. Your fan selection is based on the airflow you need and the static pressure you’ll need to overcome from your filters and duct. A remote fan is the best way to go if you can. I can appreciate that the look can have some shortcomings, but there are products available to address the aesthetic issues. As an alternative, an axial fan can be located in the ceiling between the joists and soundproofed, then ducted to the outdoors. In either case the real concern will be grease stains on the exterior of the house. Plus, grease makes a great place for pollen, dust, and all variety of other airborne stuff to adhere.

I’d suggest you talk to a commercial kitchen guy if only to get a different perspective. Ask your local restaurant if you can look at their hoods. While they will be way to the other end of the spectrum from what you’re looking for, they are built for pure function. Not to disparage the local appliance guy, but usually all they know is what they read in the manufacturer’s brochures. If the installed system doesn’t meet your expectations they don’t have to live with it like you.

The wood cladding on the hood is a nice look. Use 1/2” drywall between the hood and the wood, as it’s classified as a non-combustible material and it will save your cabinets in the event of a grease fire. Take care to finish the wood with some sort of bulletproof finish. My folks had a red oak clad hood that was really nice until the grease soaked through cracks in the finish and stained the wood. There was no saving it.

Sorry I got so wordy, although I barely scratched the surface on hood design theory. If you’d like more info shoot me a PM. I have some reference materials that might be of some help to you.

- Rob

[Jim Kaczmark]

This project perked my curiosity to see how similar range manufacturers specified their installation requirements. I compared the similar 6 burner 36" range from Viking, DCS, Wolf and Blue Star. All had 18" minimum vertical clearance to adjoining cabinetry, all had maximum adjoining cabinetry depth of 13" (wall cabinets), all had a counter top to vent hood range of 30-36". The only slight difference was the DCS required a minimum vertical distance from cooktop to combustible material (including wood covered vent hoods) of 36", where Wolf & Viking had 30". That's a key number for us wood workers. Reason was DCS had the highest BTU per burner rating of 17.5K, versus 16K and 15K for the Wolf & Viking respectively. (Blue Star was silent on this number in the literature I could find on their web site.... would have been interested in the number as their maximum burner BTU was the highest at 18K for the line I looked at & they even offer one version with a 22K BTU burner output.)