You don't provide enough information for someone to make a recommendation but you might want to do a search at build.com whose search engine lets you specify many parameters to find the right product. Many products have reviews as well.

A 450-CFM flow rate through a 6-inch duct requires a velocity of about 2300 ft/min. This is higher than the recommended range of 1000 to 2000, with the lower value preferred for cold ducts. If by 450 CFM you meant blower rating, and expect the actual flow to be nearer 300 CFM, then the flow velocity is near 1500 CFM and you are in the desirable range.

Particularly for high assumed actual flow rates in small ducts, the duct pressure loss unless the duct is very short will be significant relative to the hood filter pressure loss, making the requirement for rated blower flow rate significantly higher than with a more appropriate duct, say 8-inches diameter.

It is also worth noting that for the hood to have roughly the same containment ability over the entire entry aperture, the system flow distribution at the hood aperture has to be relatively even. This requires either a tall hood that nicely transitions the flow from the aperture size to the duct size, or restrictive baffles that choke the flow enough to balance it out. Sleek is not your friend in performing this function.

Kaseki -

We took out our over range microwave and want to replace it with a low profile under cabinet range hood. The diameter of the of the duct work is 6 inches, and due to multiple circumstances (too long to list here), we can not go above that diameter. Trying to find the most powerful unit we can that will not require any duct work higher than the 6 inch diameter.

The current duct work is in the cabinet right above the range.

I understand that Kobe sells an under cabinet unit that is only 6 inches wide, works with a 6 inch diameter duct, and is 700 CFM blower rating. Looking to see if we. have other options to consider.

Thank you!

You may have more options if you separate the two elements -- hood and blower -- into separate purchases (or at least separately priced components). The blower could be outside on a wall or roof (wherever the duct leads) and the hood selected from among many that adapt to six-inch ducts. (Hood blower control and blower need to be compatible, and installing a power cable between them feasible.) For examples of each, see the Wolf Design Guide and the recently published Wolf Ventilation Guide (both names should be searchable for links). Then, other sources can be consulted for competitive devices, such as ajmadison.com. Broan has blowers for every occasion that are mostly induction motor driven and can be controlled by standard variable motor controls. There are manufacturers such as ModernAire that will fabricate whatever you want.

Note that conversationally, at least in this forum, hood width is a measure of how wide the cook has to stretch his or her arms to encompass the hood (30 to 66 inches typically), depth is front-to-back measurement, and height is distance from entry aperture to top exclusive of duct covers. I have assumed that your 6-inch "width" value is actually a height measurement.

For wall hoods, the duct interface can be at the back or top, most often, but side interface hoods can be found.

Kaseki - You are such a wealth of information. Thank you! My husband and I are not at all knowledgable about hoods at all, hence the reason I'm reaching out for help. My husband, and a friend, will be the ones installing the hood, so ease of installation is important, as is other specifications that is needed to meet the restricted space.

Since we are not doing a full kitchen remodel, we are restricted by the current space and openings we have.

From floor to where the duct does a 45 degree (?) bend is 77" inches. From the top of the 'current' one to where the duct does a 45 degree bend it's about 45-46".

The duct is 6" in diameter, and goes up before the bend.

Would like the highest CFM we can get with the 6" duct.

We originally were considering a wall range hood, but due to our circumstances that is no longer an option. We are looking a at a low profile hood that will be a fairly simple install for which my husband will be building a wood hood for after the range hood has been installed -so on top of everything else, it's imperative for the operating buttons to be underneath the hood as opposed to the front.

We know that inserts are created for such circumstances, but we prefer to not get an insert.

Also, would like the hood to have removable baffles.

I'm sorry if I'm all over the place with my post, but it's almost 3 am and it's been a very long Saturday.

Thank you for any suggestions you have for a purchase, etc.

You will have a hard time installing under cabinet style without the CABINET/cladding in place. Other wise, you need an insert.

So..........you need to decide. You are attempting to "combine" two different installs, regardless of size, vent or blower

I should add that it is possible to supplement an internal-blower hood with an external blower. You might consider this if your planned installation proves to be inadequate under certain cooking activities.

Replace the duct roof cap or wall cap with an appropriate external blower and wire it to a control switch somewhere near the cooking area. Total flow is difficult to determine without both blowers' fan curves and some estimation, but it will be higher than the hood alone and the noise probably won't be significantly higher.

For many years I supplemented the feeble blower in a Litton Cooking Center with a roof blower. The latter was somewhere in the 600 - 900 CFM range in free air, and the Litton maybe moved 80 CFM. Together with the congested ducting then in use I obtained perhaps 200 CFM if the upper door (eyebrow hood) of the Litton was opened. (This roof blower is now connected via 8-inch ducting and a Fantech silencer to a pair of ceiling registers over my wall ovens as a supplement to my hood.)

There are a number of products (I assumed 30" width) that meet your requirements. I think the Zephyr Pisa and Genova are very attractive.

Hi Jan,

Thanks for the heads up. We are keeping the cabinet in place (just removing the doors), and building a hood around the cabinet (easy to do). :)

Lawrence,

Those hoods are beautiful, thank you for the recommendations. At this point looks aren't important to us since we decided to build a hood around whatever we install, but meeting certain requirements are. Thank you again!

Kaseki,

I will have to read over your detailed info. later tonight (running out the door now), so that I can really understand (and have it sink in), about all the detailed info. you provided.

The only reason I mentioned the Kobe 700 CFM is because the gentleman at the store where we purchased our range from recommended. it. He is aware of our restrictions. With regards to 'make up' air...although I cook a LOT, in the previous years we rarely used the blower (if at all) for cooking, so doubt I will be using it as anything more than on the lowest setting, but considered the higher CFM that would fit our case.

The duct, as I'm sure you are aware, feeds to the already existing blower outside. All [we think[] we need is to find one that fits the space for the install.

Thank you again!