Any good appliance store should have one. Best is one of the more known brands. It's called a vent liner. You also have to decide if you want baffles or mesh. If you want an in line blower or an external blower. There are a lot of very good posts on this subject here on GW. Just do a search using the word vent.

Here is a link that might be useful: Vent Hoods

I've been looking into this and been asking the same questions.

In one bathroom I have an inline blower, and in another bathroom a quiet fan motor in a box in the ceiling. In both bathroomss I bought the most expensive product I could find, in the same year. There is a noticeable difference in their noise. The inline blower was a kit. The quietest installation is the inline blower: all I hear is air moving in a straight line, not the fan or its shuffling air around.

Over a cooktop one needs a visible collector - hood space - canopy - sump - umbrella - holding filters. I think it was on the Broan-Nutone web site where I read that a 1" height canopy is sufficient and - or adequate - but that a flat canopy is not much good. So I need to build this (custom design), and if the sump is rectangular, then a rectangular to round - transition - adaptor - then after an elbow in the ducting, hang the inline - fan - blower - motor.

It can be shallow enough to free up space in cabinetry while still trapping enough rising air to be truly useful. I'm thinking of using tempered glass or plexiglas that I'd pull down and position on an angle to make a see-through front against rising smoke.

HTH
-David

Thanks for the tips, all. David, wouldn't your glass or plexi still get really cloudy and greasy, even if you did have a powerful fan? I'm not sure what an inline fan is vs putting a quiet fan on the ceiling. Does that mean it's installed in the space above the ceiling?

orchidca,

Everything has to be cleaned, whether it is transparent or not. So, given that fact, I can't figure out why you would mention cleaning.

Is it clear that a hood and a hood fan take greasy smoke outdoors? Instead of being an entry to the duct, an inline fan is part of the duct, looking like a bubble shape if you look at the duct exterior without knowing what is inside it.

You say you are not sure what an inline fan is "vs putting a quiet fan on the ceiling". I wonder what "on" the ceiling means. Might you be thinking of those ceiling fans that circulate room air?

Where your duct goes and where you might put an inline fan depends on Your ceiling and your available spaces elsewhere in your house, not on anything else. Hope this answers this question: "Does that mean it's installed in the space above the ceiling?".

Is my first post unreadable, unclear? What part is not clear? If this post hasn't helped clear things up, I'll let someone else word it all in other words.

David

Don't feel bad, orchidca, I don't understand either, even after the clarification, but you can find what you're looking for on most sites that sell hoods if you search for "liner insert".

Generally, a remote blower (fan motor) will be less noisy in the kitchen than an internal one. An internal motor is located inside the hood, whether it is custom made or prefabricated. A remote blower comes in at least 2 varieties: external and in-line. External blowers are typically located in the attic close to the opening to the outside where the exhaust dumps the smokey/greasy air. In-line blowers are located somewhere inside the duct, and that can be a few feet from the hood or a foot or so from the exhaust opening.

There's a lot of stuff on this topic in this forum. You need to get up to speed on exhaust capacity (cfm, cubic feet per minute) of air; required duct diameter, which depends on the particular blower you buy, whether you need to include a device for "make-up air", and lot of other things that will make your head spin before you're finished.

Take your time to make sure you get it right, or you might have a bad case of buyer's remorse.