Why under 400 cfms? That's just about useless.

I bought a Broan 390cfm vent insert to put in an unfinished wood hood which I finished to match my cabinets. I do not find it useless at all.

I bought both the unfinished 30" hood and insert from Kitchensource.

http://www.kitchensource.com/range-hoods/br-pm390.htm

My hood came with a liner. You may need to purchase the liner too. The liner is mentioned in the link.

most residential use 30" cooktops only need 400 cfm hoods. besides, any more than that and you should have makeup air.

"Why under 400 cfms? That's just about useless."

Quite the contrary. Mine has a max of 400 cfm, and usually I don't even use the highest setting. It does an excellent job.

It may be that you don’t use the higher settings - I suspect it depends on the kind of cooking you do in part - but why specify lower than that? You can always just not use higher settings if you don’t need them, and low cfm hoods seem to be an odd thing to look for in the general market, so explicitly restricting your search like that seems an exercise in frustration.

Above 400cfms requires make up air, an expensive thing to add if you have a ordinary, non professional, 4 burner range. Many upscale kitchens have professional ranges that have requirements above 400cfms - so need make up air too. Ordinary ranges in modest kitchens do not usually need above 400cfms or the added expense of make up air.

The range itself usually determines the cfms needed. There is no reason to go above what is recommended by the range itself.

I have a friend who is a professional baker. She does all her cooking on a regular stovetop and wall oven. She has a very pretty stainless hood - under 400cfms.

The way I read the request, even a 400cfm would be too high. But that’s a common strength I’ve seen as a cut off - so if you only wanted 200cfm (for example) you’d still get a larger set of choices looking at up to 400 and just not using the higher settings, while still not hitting the need for make up air. That’s all I meant.

PirateFoxy, I asuume it's an issue of the makeup air requirement. She didn't say anything about only 200 CFM...just up to the max of 400.

We are trying to stay under the 400 cfm because of the make-up air requirement.

Our builder mentioned how expensive it would be to install.

jhmarie thanks for the link.

We are trying to find one with the stainless steel baffles.

Can you see your mesh baffles or does the cabinet face doing a good job hiding it?

Thanks Everyone for your inputs. and suggestions.

OP, just so you’ll know, I think you are good at 400. It’s OVER 400 that the requirement kicks in. And there are many many choices at 400 and below.

My hood hides my vent insert - which is about 5 " up inside my hood. My vent is not inside a cabinet, but in a wood hood.

Kitchen - I am short and from my perspective, you can see a bit of the liner in his pic:

https://www.houzz.com/photos/my-pics-work-in-progress-phvw-vp~93784356

Here is a view from underneath:

Thank You jhmarie

"400 CFM and greater triggers MUA 399 and below does not."

Where I live, 400 CFM does not trigger MUA.

401 CFM, does.

Mechanical

Q: What makeup air requirements are associated with vented kitchen range hoods? (IRC
M1503.4, M1501.2, G2447.6)

•  Three code provisions can trigger the needful makeup air in this situation.The bottom line is
  that makeup air is always required for high-volume hoods (> 400 cfm) and may be required
  for lower volume hoods when natural-draft appliances are used.
•  M1503.4 requires makeup air for kitchen hoods which exhaust more than 400 cfm. The
  makeup airflow rate must equal the exhaust flow rate and an intake damper on the makeup air
  duct must be interlocked with the control for the fan.
•  M1501.2requires that“ducted exhaust systems”(such as kitchen hoods,bath fans, clothes
  dryers) not induce negative pressure in excess of negative 3 Pascals at the location of a natural-
  draft combustion appliance. This provision applies regardless of the rated airflow of the
  exhaust system.
•  G2447.6 reinforces M1501.2, more explicitly for vented kitchen hoods. This provision is
  independent of the rated airflow through the hood.
•  A pressure test is required to demonstrate that the depressurization level is within the 3Pascal
  limit. If the depressurization limit is exceeded, makeup air is one potential solution.
•  There is no requirement to temper makeup air.

What is the source of that question? I'm guessing those are Colorado "amendments". The standard IRC is not so kind as to make those second two codes so obvious. M1501.2 and G2447.6 do not exist, although there is;

And they still make you dig further for the 3Pascal reference, such as in the ANSI listing requirements for the natural-draft combustion appliance, but it is there nonetheless.

The 2018 IRC does have a blip about "3Pascals", but it is poorly written and would be confusing to bring up until it is actually applicable somewhere.

If anyone is interested in an insert that will fit into a 36" cabinet and is 400 cfm and meets the MUA requirement, there is the XO133SMUA.