I agree about Ventilation 101. As yourself, I've had to education myself on these matters, but unlike you, I can stare up my range hood vent, measure and picture. Any way, a squirrel cage is a type of cage in which my roof centrifugal fan/motor ensemble sits. I'm not sure of the word's origin but it resembles a squirrel's tail in shape, so perhaps it is that simple. From Wikipedia: "A centrifugal fan (not to be confused with blowers) is a mechanical device for moving air or other gases with a very low increase in pressure. These fans increase the speed of air stream with the rotating impellers.[1] They use the kinetic energy of the impellers or the rotating blade to increase the pressure of the air/gas stream which in turn moves them against the resistance caused by ducts, dampers and other components." "Centrifugal fan is a constant CFM device or a constant volume device, meaning that, at a constant fan speed, a centrifugal fan will pump a constant volume of air rather than a constant mass. This means that the air velocity in a system is fixed even though mass flow rate through the fan is not. The centrifugal fan is one of the most widely used fans. Centrifugal fans are by far the most prevalent type of fan used in the HVAC industry today. They are usually cheaper than axial fans and simpler in construction.[3] In automotive industries, fans are used for cooling internal combustion engines. The fan derives its energy from the power generated by the engine. It is used in transporting gas or materials and in ventilation system for buildings.[4] They are also used commonly in central heating/cooling systems. They are also well-suited for industrial processes and air pollution control systems. When one fan can�t afford the necessary flow and pressure, the fans must be run in series two or more, in order to achieve the goal. The pressure of the centrifugal fan is high, so it is widely used in the production and has high using frequency, the centrifugal fans in series are often applied in practical production. According to the relevant statistics, fan power consumption accounting for 12% of the total electricity consumption. It has a fan wheel composed of a number of fan blades, or ribs, mounted around a hub. As shown in Figure 1, the hub turns on a driveshaft that passes through the fan housing. The gas enters from the side of the fan wheel, turns 90 degrees and accelerates due to centrifugal force as it flows over the fan blades and exits the fan housing." One thought I have is do you need more than one fan to increase your cfm venting. Still, there is no doubt the 6" duct is a rate limiting step, as is the height away from your range. If you could do away with the hood insert vent type, and custom make or find a inverted T type vent hood with enough pipe length from your 9" ceiling to 30" above your range and which accommodates your duct(s) (6" or 8") with some fiddling, you may reach a happier compromise to allow you the range type you wish. I think I saw you mention a BS or CC. Very nice. Glad your getting some additional input. Remember to address make up air (MUA) at some point and cfm. It's a smart idea to consider the basics. Hope this helps. I'm just learning this all along with you. Here is a link that might be useful: Centrifugal fan link:

I can't comment on those specific models, but we had a Zephyr Monsoon II model AK9346AS installed about a year ago and it we found it to be impossibly loud. Their literature says the sone level on low is 3.5, which, based on this chart, is about 45 decibels. I downloaded a decibel meter to my phone and with the phone sitting on the stove 35 inches below, the noise registered 80-82 db. That's MUCH louder than advertised, and we found it very uncomfortable and annoying--couldn't hear the Sonos speaker 12 feet away or anyone talking in a normal voice, and there was a sigh of relief whenever we turned the fan off. We eventually decided to switch it out and install a Wolf liner (with variable speed knob), an inline silencer, and 1400 cfm Abbaka roof mounted blower. It's quieter on high than the Zephyr was on low. The three pieces are a more expensive proposition (even if we hadn't made the Zephyr mistake), but the result is so vastly more pleasant that I still smile when I turn on the fan. In a nutshell, if there's any way you can listen to the Zephyr and Best, preferably in a similar setting, do it. Don't trust the literature.

cpartist, thanks for the info on the monsoon (and pacemakers). I will stick with the monsoon and gas though even though lots of folks here love induction. Opaone, you must revisit the keys then after this pandemic is over! Although I think you would find it a bit different from before, more people have discovered it. But it is such a relaxed lifestyle. Regarding your above question about heat, we don't have any in this house! Megs, thanks for your input on Best, I feel that the noise level is what pointed me towards Zephyr in my initial research. Fureywoman, thank you for relaying your store's confidence in Zephyr. We emailed architect today and he is fine with our choice--which supports the theory that the cabinetmaker was the source of the recommendation.

@TxMomma really appreciate the insight. I will have a 36” wide Wolf range, so I need the 42” wide vent insert and that one has the 1200 CFM capability. But I doubt I’ll ever need to use it on that setting and my contractor assured me that my space is large enough with sufficient ventilation so that makeup air wouldn’t be an issue for me. I also found vent-a-hood much more expensive and my appliance person highly recommended the Zephyr brand and the Monsoon II in particular because of its depth and also the LED lighting in the front and back of the insert. Sounds like such a nice practical feature. Would love to hear how it sounds/works once you have the chance to test it out. Thanks