Slate will show all of the grease spatters. Quickly. Nt the best choice for a kitchen that ctually gets used. If you're gonna clad the hood in copper,think about doing an integral backsplash, maybe with shelf. It's done in stainless frequently. Be prepared for the high heat usage to change the color close to the back burners.

Mounted that high, you're looking at doing something deeper than 27''. Maybe 30''. Then the width should be at least 12''-18" wider. With at least 1600 CFM. Couple that with your other reuirements, you're in custom commercial territory, with the noise and price tag to match. Call a local restaurant HVAC company.

Hollysprings is on the right track here, but it may make the requirements clearer to explain the order of issues.

The rising effluent expands, and this drives the need for larger hood apertures the higher the hood is mounted. The aperture requires a certain air velocity from the hood blower to ensure that effluent captured by the aperture becomes contained and removed effluent, that is, doesn't leak back out. Velocity times aperture area then determines flow rate (CFM).

Commercial kitchens use hoods with typical height of the bottom of the aperture set at seven feet for easy clearance. These hoods can be three feet front to back and, depending on whether they have side skirts, overlap the cooking surface by a foot or more on each end.

So, for effective capture and containment, the cost of improving aesthetics by moving a hood higher is a larger structure, a larger required blower, and more make-up air. In other words, the cost escalates perhaps in proportion to the square of the distance one increases the hood height.

Yes, you can even build a system at 9-feet up that will be effective, but be prepared for the initial and recurring costs that result with such a configuration. There is a reason why HVAC power is a major cost of restaurant operation.

Please see link for a seven foot high, aesthetic hood. Note that it illustrates that modest cost, high aesthetics, and high performance cannot all be achieved at once. Generally, you can have two out of three.

kas

Here is a link that might be useful: A large enough copper hood

Well, that helped to convince me to use lower height for hood, which means that my little "roof" will have 2 lines. Will have to get creative.

Just a quick note, this kitchen will not see a heavy use, so I am not worried about slate getting greasy. It will be sealed and residue shouldn't be a problem with proper ventilation.

Original question still stands - I will need a hood with a wall switch. I can swear I saw at least couple of them before we actually decided on this design and unfortunately I haven't noted the make/model.

I guess once I see the actual model and specs, we can discuss about proper mounting height, etc.

If you use a remote blower, most can be controlled by a wall switch or a wall control. Broan/NuTone should have products of this type, as will Fantech, Abbaka and others. This approach goes with buying a hood liner that only has a shell, baffles and lights.

Hoods with internal blowers could be "remodeled" to be externally controlled. This would require rewiring in conformance with various codes and might, depending on locale, lead to rejection by the AHJ because the hood's UL or CSA listing no longer applied. In any case, the existing hood mounted control would become redundant.

There may be hood liners with internal blowers that are convertible to wall switch control, but I have never looked for any.

kas

kas, you are talking some serious $$ as Abbaka is way over our budget.

I agree on converting the control to wall switch, but it would only work if original controls are not digital. I ran into similar problem with DC motor ceiling fan, which couldn't be controlled by the wall switch because of it's multiple speeds. It had to be controlled by the handheld remote, which is horrible.

I still have a picture in my mind, of horizontal wall switch that came with some hood insert, but I can't remember what it was. Have to start browsing them again.

I haven't bought any lately, but my past experience with Broan/NuTone blowers is that these blowers have been powered by induction motors, which should work with normal triac motor controls.* My Wolf centrifugal style roof blower is actually manufactured by Broan, and the control built into my hood is a diac/triac configuration, sized for the 1500 cfm rated blower.

I also have a much earlier purchased NuTone roof blower in downblast style housing that uses a typical wall control for speed.

When "brushless dc torque motor" designs are used, which require synthesized multiphase frequency drive with Hall-effect feedback, the circuitry is much more complicated, and so can be the intermediate cabling, making such designs less suitable for wall switch control unless the wall switch is mere input control for the motor controller that should be in close proximity to the motor.

So if I were you I would aim for an induction motor external fan and I would start with Broan's on-line data.

kas
_____
* Diac/triac motor controls, and other architectures for modest sized motors that are typically sold as wall switches, are much like lamp dimmer wall switches except that they go from off to full power at turn on, slowing down with clockwise motion, whereas lamp dimmers go from off to minimum, brightening with clockwise motion.

Multi speed DC motor will likely require a specific accessory switch designed to work with that particular unit. Will have to double check for sure, before making the purchase.

Big plus of DC is extremely low power consumption and quiet operation.

So you are leaning towards Broan fan unit and separate fan-less insert/enclosure? What fan-less insert would you advise?

Will start digging into Broan literature.

I don't recommend hoods that I haven't owned, but am willing to critique those that apparently deviate too far from the functionality of standard commercial designs. But that is because my bias is toward odor and grease removal, with cost and aesthetics then traded off while trying to keep noise down and make-up air complexity under control.

You will need to find an insert that will fit your intended cabinet that surrounds it. Or vice versa. This may be a somewhat recursive process. An insert is fairly simple, and by its nature doesn't require a fancy exterior. It does need to be cleaned, so it needs removable baffles and stainless steel construction. If you can't find one that fits your possibly unique requirements, then companies such as Modernaire and Prestige can make them.

You will need to decide on your tolerable cost point.

I can advise on flow rate, but I have commented on that in endless other threads, so you might search there first. Also see my My Clippings for references. If you care about ventilation, then expect it too take a lot of research time and not a little bit of money.

Searching on this site can be performed by the local search engine, or generally more thoroughly by using Google advanced search and setting the site to ths.gardenweb.com.

kas

As for hoods with wall switches, Thermador and Best/Broan inserts can use ones that are wired. Many other manufacturers sell hoods that have wireless remotes. Those would work with any type of blower. Or as kaseki said, with any hood used with an external blower, you could just not wire up the internal controls and use a solid state speed control and wire up a dimmer for the lights. And I think when kaseki mentioned Abbaka, he was just referring to the blower. Their hoods may be out of your budget, but if you want an exterior mounted blower Abbaka is a common choice that can be used with any brand of hood/insert.

And being in the HVAC business, I must ask, what are you going to do about make-up air? It's certainly a new thing I've had to learn about, as this whole trend of giant pro ranges and high CFM hoods to match has really gotten bigger in recent years. My personal opinion is that EVEN despite the pro ranges, people are putting in hoods with too high CFM. IMO there is no need to go above the cutoff for makeup air unless you have a high BTU range, 400 and under is fine for most people. 600 maybe if you do a lot of cooking with multiple burners/frying or have a pro range. I couldn't at all see going above 1000 unless you will be doing indoor grilling. As kaseki talked about, the closer the hood, the better, because then you will be able to get away with lower CFM, and lower CFM makes everyone's life easier.

This post was edited by hvtech42 on Tue, Feb 18, 14 at 20:18

As for makeup air, 4x6 window will be just 1ft away from the edge of the stove, so that's an obvious solution.

I really don't plan to run the 1,500cfm fan in full speed all the time. Aiming to use lowest speed most, at lowest noise level (even though it would likely be an external fan unit, window would be really close to it). For internal fans, I really like Kobe hoods because of their quiet operation.

Internal or in-line fan would have my preference over external, but it can't be too loud.

This external Broan setup should run about $1,200
Broan 335 blower: http://www.broan.com/products/product/6c70c35a-fdc6-4ea1-91db-076d440e26e5
Broan RMIP45 insert: http://www.broan.com/products/product/113d81cd-df45-4cb6-96a5-324f8f2316f1
Broan 72V variable speed wall switch: http://www.broan.com/products/product/73cb552d-67cf-4dc5-8f4b-642029f54ab6

I also looked at Tradewind, but their literature is horrible. Still interested though.

And Best, but it might be just too much $$.
They have neat looking wall switch ACW1WH: http://www.bestrangehoods.com/store/products/productdetail.aspx?id=987c8052-c832-4d10-a9d4-5f75ea751e86
Not sure whether it would work with external blowers only or also power packs.
Best CP37I482SB http://www.bestrangehoods.com/store/products/productdetail.aspx?id=b0e8480d-e372-4d90-ab2b-94259885f6c0
It seems to be the only choice for 22" deep and isn't cheap, for sure. 2 sones at lowest speed.

Do you have a fireplace? Do you have any gas burning appliances besides your stove? How tight is your house? I don't like the "open a window" idea. For 600 CFM, not tight house, all electric, maybe. 1000+ cfm? That's another story.

Does your area enforce the makeup air requirement for hoods greater than 400 cfm? I assume not based on your response, but that's something to check if you haven't already.

House is very tight. Spray foam, good windows, etc. 1 wood burning stove with damper. All gas burning appliances are direct vent sealed combustion (except for dryer and gas stove).

No building codes to worry about.

Why you don't like open window idea? How different is it from makeup air vent? Again, it's 1 ft from the edge of the stove. It would have to be open at rare occasions, with heavy cooking. Just cracked, if that at low speed.

BTW, entire house will be pressure balanced with ERV.

Can we assume you live in a warm climate so that you can keep that window open all year round?

There are many threads here about MUA. One thing I'll mention is that an open window next to the stove changes the airflow across the stove when the vent is on. Effluent gets pushed sideways instead of upwards. Not to mention pushing the flames sideways.

I would be curious how much air your ERV makes for you and how this would apply. Otherwise I would spend a few bucks on a barometrically controlled input damper, filter (and heater if required) and connect it to my HVAC. But that's just me.

It may be possible, depending on open window area, for a window screen alone to develop a pressure drop sufficient to back-draft a fireplace or wood-burning stove. A small window opening may yield enough pressure drop to back-draft a dryer.

Weedmeister is correct about the MUA localization; it is better to develop a large sectional area of moving air at a distance from the stove and hood to keep the MUA relatively laminar when it gets to the cooking area. In other words, opening a window down the hall is in principle better, and this approach should be compared to the nearby window for how the effluent is disturbed as it rises. On the other hand, if the local MUA flow is relatively undisturbing, then there is less need for the air to be heated if the external temperature is only modestly cooler than the house.

Whether a window is suitable either way will depend on the temperature differntial, inside to out, and the residents' tolerance for cold or heat.

kas