We are using an inline exhaust fan that will be located in our attic. We purchased an optional silencer to go with it, and it is very quiet. Tolerable without the silencer. Great with it.

Unfortunately, most wall ovens do not have their own vent interfaces. What I did was put a pair of registers in the ceiling over the ovens, with their connecting ducts joined in a Y-adapter, and the output duct connected to a roof blower. The blower was a re-purposed NuTone down-blast roof blower purchased many years earlier to provide a boost to the vent of a Litton "kitchen center." The register boxes take (IIRC) 12 x 14 furnace filters to help keep grease particles from the ducts. Note that not even a commercial "eye-brow" hood will capture the smoke escaping a broiling oven when the door is opened. What these registers do is help pull effluent from the ceiling area and slowly clear the kitchen in concert with the main hood. The only way to successfully deal with opened ovens is a large hood right over them, or a commercial porous ceiling ventilation system, such as illustrated here: http://www.kitchen-ventilation.co.uk/heydal Yes, the MUA now becomes more complex because the control has to be "closed-loop" instead of "open-loop" and thus needs a servo control system to control an even larger MUA blower. My kitchen blowers' combined output is 2500 CFM (zero static pressure rating), and likely pull a total of 1500 CFM when there is sufficient MUA. With both blowers having variable control, the actual CFM can be anything, windows can be open or not, bathroom fans can run or not, etc., so the scheme is to control on differential pressure between my kitchen and the vented attic. Not all parts of this system have been purchased and integrated. My excuse is that my honey-do list is very long and keeps expanding. Items in place: Roof down-blast housing on pedestal for air intake interface with attic Hydronic heat exchanger in attic with its separate control loop to my furnace (functioning) 3-ft square diffuser in hallway facing kitchen Sensing system installed Control system components mounted in basement; Fuji computer purchased but not yet incorporated Key elements yet to be obtained (mostly from Fantech, I expect) Big axial blower sufficient to flow around 1500 CFM through the pressure losses of the ducting, air filter, and heat exchanger. It also has to fit through the attic access stairway. Current-loop control fan motor driver Pleated air filter box Damper Various sheet metal interface sections I should add that my only combustion appliance is a blown oil burner that has its own sealed MUA supply, so delay in completing this kitchen MUA system is an annoyance, but not a hazard. In your case, a carbon monoxide warning sensor is suggested. kas

We fully agree that homeowners should do extensive research including the use of Houzz and other social forms But that also should in our opinion includes speaking to licensed professionals in the supporting fields for their project And that is exactly what we did And we did meet with licensed Structural Engineers , Hvac, general contractor, Electricians and plumbers etc. Every one of them as well researched from their licensing to customer reviews/feedback Houzx is a great form to use but again you don’t really know the background of the people you’re speaking with and their opinions are worth noting but should be validated There comes a point in our experience and knowledge that we have to bow out because we are not professionals in this field Anybody who takes offense to our bowing out should not ...we know limits and cannot provide more than we already have. Please start another strand for future questions as we will not be commenting on this any further.

54-inches (4.5 ft) x 2 ft = 9 sq. ft. Desired volumetric flow rate to achieve 90 ft/min across the hood aperture is 90 x 9 = 810 CFM. Blower rating needed to pull 810 CFM with decent MUA will be around 1200 CFM, as you noted. Fantech provides 'fan-curve' data in the form of tables, and also plots. A 1200 CFM unit (at zero static pressure) will show a value near 810 CFM at some pressure drop (about 1.2 inches, w.c., for the FKD10XL). Excluding MUA, most pressure drop will be from the hood baffles, unless one has several tens of feet of duct. It would be useful for you to obtain pressure loss vs. flow rate data from Bluestar. Fantech in-line blowers are, I think, axial blowers (like a turbo jet pressure section) rather than a flat plate with radial fins (like turbo chargers use). Broan blowers, including inline, appear to all be the plate type. There is nothing wrong with these, but they may have a different characteristic fan curve shape than Fantech's blowers. I've never plotted both together. (It is important for residential blowers operated at uncontrolled pressure losses and any speed from low to high that they have monotonic fan curves. Else they might 'hunt' at some setting. That would be annoying.) Plate type blowers are least conspicuous built into a roof cap. Commercial up-blast blowers use induction motors often tied to the fan assembly via a belt and sheaves. These can be tailored to provide the desired CFM at lower fan speeds, thereby reducing noise. They are, however, significantly more conspicuous on the roof. The primary advantage to using a hood manufacturer's specified blower is that it will directly adapt to whatever fan speed controls are built into the hood. Other blowers may require some type of adapter or control replacement. So a Blue Star hood's control nature might have to be determined. My Wolf hood adapts to my Wolf blower, made by Broan/NuTone, and likely would work with any other single wire pair induction motor blower up to some motor power limit. The Fantech FKD10XL data sheet show curves for a 5-step transformer control, and for no control. One would have to check with them for compatibility with whatever the Bluestar hood uses, such as phase control. If you use an in-line blower, you also have to find a suitable roof or wall cap. Fantech many sell these. You should have a damper at the hood and also at the roof cap. You need to plan out the entire hood duct path. Is there room for a silencer? Can the duct path rise over its entire length (desirable)? What elbows are needed? Fantech makes some duct couplings that may prove useful. Hanger strap material will be needed. Sound dampening material may or may not be needed depending on blower assembly vibration, which is mostly, I expect, due to blower fan assembly balance quality. Best to match MUA actual flow rate to hood actual flow rate (ex: 810 CFM). This avoids all (well most) pressure drop in the house, conferring safety with combustion appliances and keeping the wall dust in the walls. If active MUA is needed to do this (depends on combustion appliances and their MUA, if any) then a blower that can provide the required CFM at the MUA path pressure loss (usually any air filters, but could include the heating scheme if hydronic). As usual, the duct diameter in the hood exhaust should support a full speed flow rate of 1000 to 2000 ft/min. The otherwise clean MUA path is not grease deposition constrained, but larger will reduce pressure loss if there is room -- useful particularly with passive MUA. I'll skip MUA control in this message, but it needs to be addressed. Commercial rigs usually run at constant speed (exhaust and MUA), so tuning is easy. Residential variable flow rate, along with perhaps a need to deal with other exhaust fans and fireplaces, imposes more difficult conditions for blower control. You might need a Fantech MUA setup, or their 10V control type blowers run by a controller trying to keep house pressure relative to outside within some bound.