^^Looks like you need something from Fantech's FKD series for range hood exhaust....residential applications such as kitchen range hood exhausts.

https://www.supplyhouse.com/Fantech-FKD8XL-FKD-Series-Round-Inline-Mixed-Flow-Centrifugal-Fan-8-Duct-836-CFM

With sufficient entraining air being pulled into the hood, the internal duct temperature should be modest. However, a cooking fire might well damage the motor (maybe the least of the concerns).

Usually, though, the hood intake flow is sized for the hood, so the rising plume volumetric flow rate would be only a fraction of the total flow.

Does this warm area of SoCal actually call for MUA? If you have no combustion appliances taking air from the house interior, a simple 10-inch duct from outside, via an electrical damper and incorporating a furnace filter should be enough MUA. There would be some additional (besides the hood baffles) degradation of the hood blower performance, but not nearly as much as starting with only 430 CFM (free air performance) pulling air through the house leakage paths.

Wolf rooftop blowers (made by Broan/NuTone) have dampers. Another damper at the hood should be used in cold climates; not sure about warm climates. It would likely minimize damper flapping in gusty conditions. Fantech sells passive dampers; Honeywell has electrical and pneumatic dampers. Probably others.

The silencer goes between hood and blower.

Transitions can be used as needed, given that one recognizes that they will have a pressure loss.

Thank you, Kaseki.

I was hoping that you would chime in :D.

" Does this warm area of SoCal actually call for MUA? If you have no combustion appliances taking air from the house interior, a simple 10-inch duct from outside, via an electrical damper and incorporating a furnace filter should be enough MUA. There would be some additional (besides the hood baffles) degradation of the hood blower performance, but not nearly as much as starting with only 430 CFM (free air performance) pulling air through the house leakage paths. "

I'm pretty sure los angeles code requires for MUA system anything exceeding 400CFM. I know FG8 is 461CFM ( hoping that the inspctor would be little bit flexible when I beg him/her pointing out how drafty my house is and the facts that I have three working windows in the kitchen.

I've done some further readings on the damper and most of them over the time ( naturally, nothing stays pristine conditon as a day of installation :) )it doesn't work due to the grease piling up. so one should install it somewhere it's accessible to clean/repair/replace/.

One near by hood insert and another one at the roof cap. ( for mostly colder environment? but I don't mind having additional one ) got it. I'll take a look passive, pneumati and electrical kinds to compare. I don't know what are mostlly used for kitchen hood purpose. for the roof cap, I'd love to get a copper kind but it will be corroded since will join into galvanized duct, right? I can get a stainless steel. urghh.. so many choices and I'm only replacing hood/duct!!

wdccruise

That was the model Fantech recommended it when I contacted them. Thanks for came by and remind me to double check.

I have a damper above my Wolf Pro Island hood, not yet degraded after 10+ years, and a pair of dampers over a pair of ceiling registers above my ovens, not yet degraded. The kitchen end dampers are accessible, but the pre-filtering seems to work satisfactorily in keeping them operational. The Wolf (Broan) roof blower has a damper that operates with the blower and as far as I can tell does not have a problem with grease.

As a reminder, the purpose of hood baffles is to remove grease from the larger end of the particle spectrum. The rest is expected to be blown out as an aerosol. Obviously, some impact settling on the duct will occur, but it usually just turns to a thin varnish. And this gets us to running an undersized blower for the size of the baffle area. There will be a minimum air speed at which the baffles will function a centrifugal expulsion of grease particles. This will vary with design and particle mass. If you cook anything greasy, and I include here simmering bacon with practically no upward plume momentum, you should run at near full power, given that you provide only 461 CFM (probably only 300 actual even with free flowing MUA) of blower performance.

I'm not sure how long a copper/galvi junction would last in LA, maybe decades if kept externally dry, depending on moisture in the duct. In any case, a short section of stainless duct would likely keep them apart enough to last. Electrolytic corrosion isn't my field, but tinning the copper where it connects to the galvi might also work. Also, Fantech has clamp type couplings with rubber on the inside. That would definitely separate the metals.

I'm very very very sensitive to smell and this is why I've got 46 inch wide hood although my range is still 1950's 39" inch wide (the case is wider, but actual burner to burner width, center to center should be 27 inch ( guesstimation ) vintage okeefe&merrit oven. Major reason i haven't cooked in this house for past seven years is because of the smell. Eeven after new hood installed, I won't cook steak or fried( stir-fry, yes) or anything crazy like that. but hearing cooking bacon( which I consider " normal cooking ") will be challenged worries me. And I'm very close to go back to the drawing board and change to 10 inch duct with more robust CFM and add MUA system.

I only have very surface knowledge of MUA system. I'll share what I think it is and please correct me.

A kitchen hood will suck a lot of inside of the house air when on so in order to make up the air you lost by kitche hood exhausting the air, you need to bring a fresh air from the outside. otherwise, you will be in danger of having too much CO2 from furnace or water heater (?) or washer/dryer ( gas ). I have a central heating system sitting on an attic but not AC unit.

MUA systme will connected to heating system vent and the kitchen vent system will be totally separate entity, that these two won't connected with any vent pipe between these. and the MUA part of vent that will be added on to heating system also need to be penetrated to the roof ( in my case, it could in exterior wall in other home when it's feasible ), or is there already vent within heating system that no additional vent pipe and the roof cap is needed?

As you can see, I don't have any knowledge on the HVAC system at all.

I wish there is a pre set "kit" that i can add to the heating system. but I'm not sure if there is such a thing exist. below link is 8 inch duct but if what I've wrote here so far is correct thenI can reach out to them and see if they have 10inch version or..... MUA doesn't have to match kitchen blower duct size?? I'm so lost, yikes.

I should add that I will get 36 inch gas oven or 36" gas cook top and spearate ovens in few years. let's see if not having a proper hood has been actual reason or an excuse ;)

https://www.supplyhouse.com/Fantech-MUAS750-Makeup-Air-System-750-CFM?utm_source=google_ad&utm_medium=shopping_neutral&utm_campaign=Shopping_Neutral_New_users&gad_source=1&gclid=CjwKCAjwoJa2BhBPEiwA0l0ImFkPbCjc0DUwjvHw_Yn0URgKeQZGbxgiqKXsYisG-avYIBSkBqELchoCvFsQAvD_BwE

I recommend 90 CFM per square foot of hood entry aperture to assure containment of whatever plume areas the hood overlaps (ideally all of them). So if your hood is 46 x say 22 inches, then the area is 7 sq. ft. 7 x 90 = 630 CFM. To achieve this with typical conditions, the blower's rated flow rate (at zero static pressure) needs to be about 1000 CFM for typical blower fan curves.

No air leaves the kitchen that isn't replaced. Either the MUA system (such as it might be) replaces it, or house leakage, open windows, whatever replaces it. If this replacement causes the house pressure to drop, the hood CFM drops and combustion appliances, if any, may (!) be back-drafted, with the risk of CO introduced into the house.

If the attic is where the furnace is, and it is ventilated, then CO into the house seems unlikely. Typically, Code Enforcement doesn't measure pressure in the house, just declares that you need an MUA system that meets certain standards, and the minimum of these is a big hole with a damper and screening. If you use a 10-inch duct for the hood, use a short 10-inch duct for the MUA if you can find a place to put it. If you pick up air on the roof, and duct it to the kitchen ceiling, then that is another option. Here is some light reading to get you started.

Please download and read the first dozen or so pages of this tome to understand what you are striving for:

https://www.tagengineering.ca/wp-content/uploads/2015/02/KVSApplDesign_catalog.pdf

Please review these FAQs, not that they are complete by any means:

https://www.houzz.com/discussions/2328297/range-hood-faq-personal-notes-updated-10-31-2007#n=20

https://www.houzz.com/discussions/5161173/hood-faq#n=101

https://www.houzz.com/discussions/6099827/exhaust-hood-faq-ii#n=113

https://www.houzz.com/discussions/6040827/range-hood-noise-project

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

There is also some MUA discussion over on the HVAC forum:

https://www.houzz.com/discussions/5888450/seeking-muas-advice#28657635

https://www.houzz.com/discussions/6078111/cost-to-add-a-make-up-air-system-for-kitchen#n=65

More elaborate MUA is needed if you need to pressure balance the house (for a fireplace, say) or heat the air, or cool the air.

The Fantech MUA is an option. You can likely argue that 750 CFM capability is greater than what your 1000 CFM blower can achieve pulling air through the hood's baffles.

Please search the forum for 'MUA' to get more examples.