A remote (as Wolf puts it) outside blower might be quieter than one in the hood, and could possibly be made larger (higher spec'd CFM) and run slower to keep down noise and still move the needed CFM (90 CFM/sq. ft. of hood entry aperture) at the pressure loss resulting from baffles, ducting, and make-up air path. As for in-line, it is probably intermediate in noise assuming one can actually fit one in the space.

In-hood and outside locations should be easier for maintenance, if any is needed in the future, unless you panel the soffit for easy removal.

Better is to use a silencer between blower and hood, as it will remove most blade tip turbulence noise and half the duct noise. From the image, you may not have room for a Fantech round silencer, but you can look up dimensions at their site based on what duct size you are using.

Is there some impediment to using an outside blower?

What @kaseki said. Inline or external should both be much quieter than in the hood. I'm a fan of inline blowers as well as external and if you're doing a false cab then you could easily have access to it. Make sure they mount it w/ perf strap.

More: https://bamasotan.us/range-exhaust-hood-faq/

BTW, I'd go 42" wide if you can.

Thank you both very much!

@kaseki my husband nixed the remote blower as the location is in a common travel path and the asthetics of it just doesn't work for him ;)

@opaone I would prefer 42" (that's what we currently have)l. Wolf has a 40" or a 46" insert and I think I may have a hard sell on going to a 46" with the hubby. And thanks for the link, that gives some more to think on.

I hadn't really thought about the silencer with an in line blower but if we can make it fit that is a good option.

I'm back to the drawing board, I'll look for a 42" from another manufacturer that has an in line blower.

Thanks again, both of you are so helpful on this forum, I have learned so much from reading your comments to others!

Without the remote blower, don't you have a duct cap there that is more or less just as large? The effluent dumped into the travel path will be the same.

And one hopes that you also have a damper there.

@kaseki fair point, We have a custom vent cap. It’s copper to blend in with our red brick exterior. He doesn't want to have to find one (or custom make) it again, if its even an option.

I’m not sure about make up air. I don’t think anything was done with our previous hood fan. Could that be because it pulled low CFM’s or the space is large enough that it‘s not required? Our kitchen is in an open area, about 350 sq ft.

I assume we need the same size duct for MUA as the hood fan. I’m not sure where we’ll run it. Could it go down to the basement and thriugh the crawl space?

I wish I had paid more attention when we did the previous reno.

No air leaves the kitchen via the hood that isn't replaced with make-up air. This air may be supplied by wall leakage, or by a deliberate system. No matter how large one's kitchen and/or house, vent air is not pulled from the interior volume until the house implodes. It only takes a very small differential pressure across the blower to essentially shut it down so that very little air is moved outside. Further, this pressure is typically sufficient to back-draft combustion appliances potentially bringing carbon monoxide into the house.

Outside air, in most cases needing heating in winter, has to be supplied to the kitchen in some manner. Please read MUA related threads here.

At present, we haven't specified the hood, or its rated CFM. Once those are determined, preferably from plume characteristics, MUA can be addressed.

@kaseki Thank you for all your help! I've done more more research and there is a vent in the kitchen which I though was connected to the HRV. After looking at photos taken through the previous reno I'm not so sure. I suspect it is for MUA. Once we open the walls I will know for sure and address it. Fortunately the location of this opening can run easily to an outside wall if need be.

You have helped me in understanding what the next step is!