All of the above may be true, but are not in themselves totally limiting. In general, there is always a blower that will move a desired air flow volumetric rate through a given duct, but one might not want to operate it, listen to it, or pay for it. But in this case we are on the margin, and feasibility is not prohibited using conventional devices.

For example, I have a Wolf/Broan 1500 CFM rated roof-mounted blower operating with a 10-inch duct, and given various estimated pressure losses, expect that it moves 900 - 1000 CFM. A 1000 CFM rated typical hood blower, no matter how large the duct, at a minimum will be significantly restricted by the hood baffles, and at a maximum by any added MUA pressure losses, and would be unlikely to move more than 700 CFM in use with a hood. An 8-inch duct has a sectional area of 64% of that of a 10-inch duct, so the pressure losses operating at 67% through an 8-inch duct of the air flow rate through a 10-inch duct will be similar.

In general, one wants to select a blower having a fan curve that supports the desired flow rate at the pressure loss that one estimates is present.

Without my looking up the specified hood, let us assume that its entrance aperture is 42 x 27 inches or just under 8 sq. ft. This calls for 8 x 90 CFM/sq. ft. or 720 actual CFM. A typical 1000 CFM blower may achieve this with a 8-inch duct, and one certainly can check the assumptions against blower fan curves (where available) to either ensure adequacy, or at least force the MUA system to be active and not cause significant pressure loss. Note that this doesn't violate your appliance guy's opinion about duct flow rates, although I am sure that his view is based on typical in-hood blowers.

If you have the room in some part of the duct path, then including a silencer will help reduce noise back at the hood for only a small added pressure loss.

In any case, numerous commercial kitchen ventilation blowers can be found that will pull 720 CFM against any pressure loss likely from a well designed hood/MUA setup.

It is quieter to move a given flow rate when the fan blades are large and moving slowly than small and moving quickly, as the latter generates more high frequency noise from turbulence.

Induction motors can be controlled by rheostat adjusted phase circuits, and these can be put into hoods. My Wolf hood has such a control, and now the technology allows for it to be performed with better techniques at low cost.

These comments are meant to touch on most of your questions, but feel free to delve deeper as needed.

kas

kaseki, thanks very much for your response and insight. This and your many previous posts and linked materials have been a huge help in learning about the science of air movement and effluent capture!

I got all of your points up to this part "Induction motors can be controlled by rheostat adjusted phase circuits..." I've googled what they are and understand the general idea, but are these modifications you made to your Wolf/Broan system and therefore something that my electrician/hvac person potentially could make to whatever hood/blower configuration I choose?

The Wolf hood came with a rheostat controlled motor controller capable of operating their 1200 and 1500 CFM blowers. This controller is actually a simple diac/triac circuit* such as one could have found described in a '70s GE Semiconductor Engineering Handbook. [Title approximate because I don't want to take the time to dig it out and look.]

This type of circuit, or more complex ones nowadays built using integrated circuits, are the essence of rotary dial motor controllers widely available from electrical distributors and big-box stores for use in electrical boxes.** Given a hood with a control that does something else, it should be possible to rewire and replace whatever is in the hood guts. Please note that getting into the guts may not be trivial in any particular hood embodiment, and bets are off assuming that a particular off-the-shelf controller will fit. Revising the hood circuitry qualifies as a "science" (actually engineering) project, and technically violates the NEC (NFPA 70) requirement that all electrical devices be approved for their function.

Also, the working assumption here is that the motor is powered by a two-wire with ground circuit, and not by using switched leads (multi-wire) to different points in the motor windings.

*See instead https://www.electronics-tutorials.ws/power/diac.html

**A rotary motor controller differs from a rotary lamp controller by certain circuit details and observationally by a CW rotation from OFF to ON may be seen to yield full motor power, with further CW rotation slowing the motor down. Lamp controllers go from OFF to ON at a dim condition, and then brighten the lamp with further CW rotation.

I have almost the same situation. 36RNB with griddle in peninsula. Prizer 36x27 hood with 1000cfm roof mounted remote. I too was limited to 8" duct, but my roof blower is only about six feet away. When I ordered my hood I specified 8" outlet vs 10" eliminating the need for a reducer. You might check with Prizer to see if they will do the same for you.
The Prizer uses a three speed vs a variable fan, and I rarely use the high speed, other than wok stir fry, or searing steak in cast iron. Low - Medium speeds suffice when needed.

Thanks again for the info, kaseki. Fairly certain I don't want to mess with any guts if I don't have to, but all good to know!

cookncarpenter, ah yes, it must have been your setup I remembered reading about, so many thanks for your reply. Great to know that Prizer accommodated your request. Fingers crossed they will do the same for me!