If you install 400 CFM and over hood-vent be sure to plan to provide make-up-air to meet code compliance.

There is no overkill, but ... Many typical liners, including Wolf's, may not be deep enough (front-to-back) to fully cover front burner plume expansion.

I don't see 42-inch liners in my 2021 Wolf Design Guide. Perhaps mine is out of date.

If we assume a liner capture aperture of 40 x 19 inches, then the capture area is 5.3 square feet. At a minimum, you want 90 CFM/sq. ft., or in this case about 500 CFM. To get this in a typical pressure loss system (baffles, hood transition, duct, MUA) you will need a roughly 700 CFM rated blower. To keep noise down you will certainly need a silencer in the duct between the blower and the hood.

In any case, I strongly encourage you to consider how much of that smoke you want to escape the hood, and hence whether you should go for a deeper hood.

If an undersized liner is used in a wood cabinet hood, the uncovered interior should be faced with stainless steel. If there is some volume below the baffles to the bottom edge of the wood hood, then we can consider the hood size to be larger. Not sure if it would be deeper pending more information. If so, we can calculate based on the entire hood entry aperture as see that higher flow rate is called for.

Note that the noise from a silenced Wolf hood/blower system (such as I have) will be dominated by baffle hiss, and this could be louder in your case if the large hood entry area is doing actual 90 CFM, and the inner liner area is doing some multiple of that.

Check out an Asian restaurant for how far towards the cook the hood entry aperture extends. Scale down from 7 ft to 6 ft hood height.

Basic rule: the farther a hood system deviates from standard commercial design, the greater the penalty on either power efficiency or capture and containment efficiency.

P.S. Search this forum for MUA threads. You need to plan MUA in parallel with the hood system design and the house structure design, and often with the HVAC design. Usually, MUA is the more difficult system to integrate.

@kaseki, you’re right. It’s 40” x 22” deep liner https://www.subzero-wolf.com/wolf/range-hood/40-inch-pro-hood-liner-22-inch-depth. It’ll go over a 36”x21” deep induction cooktop. Hopefully that should be sufficiently deep.

I’ll ask the rep about a silencer. Noise level is subjective I know… all we want is not a jet engine taking off but we can tolerate normal amount of fan noise. Growing up we have your typical Chinese style aftermarket hood like Pacific or Fotile so I’m pretty accustomed to strong suction noise :)

So basically sounds like oversizing the blower is not necessarily an issue. Also the remote blower / box will be right outside the wall on the ground floor (literally opposite the wall). I just don’t know if in line vs remote would make a difference given the short duct run but my assumption is yes…

And our GC said the HVAC team they use have installed many MUAs over last couple years especially during COVID where ppl we’re getting larger hoods during remodel, so it sound they are quite confident in the system and setup required for such application. I’m no expert and at some point I’ll have to trust what we pay the experts to do!

If you’re really asian you would know that you need to plan a second outside or garage kitchen to do your real flavorful cooking.

All joking aside I wish we couldve gone bigger with our system but had to go with the Wolf 1000 cfm inline blower. Suction is good but for the types of cooking my wife does with our Asian spices, wish we couldve installed the 1200 external blower.

See also some @opaone threads here on his commercial hood and his treatise:

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

If you are going straight out a wall, you might as well use an external wall/down-roof blower. These typically have built in dampers.

I had a 1200 cfm in my last kitchen. My “new” kitchen (different house) is 600 or 900. It’s not enough for high smoke on cast iron; I will go back to 1200 or more when I remodel.

Don’t let the make up air crowd scare you: yes you need it, and of course getting the smoke and odors out is critical for anyone making a lot of smoke.