How Does a Ductless Range Hood Work?

Based on functionality, range hoods can be broadly classified into ducted and ductless hoods. The main difference between the two is obvious from the name, ducted hoods are vented outside your home whereas ductless hoods do not have vents. Instead, the air is passed through filters and it sent back into your kitchen. This is the reason they also go by another name, recirculating range hoods.

how does a recirculating range hood work
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If you have a gas cooktop and do not have the option to leave a window open or ajar while cooking, I suggest that you DO NOT buy a ductless range hood because the carbon monoxide and other harmful gases (when in high concentration) need to be ventilated out of your kitchen and not simply recirculated back. The charcoal and grease filters that are present in one of these units will not get rid of these harmful gases

Purpose of a Hood & How a Ductless Hood Functions

A range hood is meant to get rid of odor, smoke, grease/oil, steam, [heat and harmful gases]*. The two marked in an asterisk are functions a ductless hood cannot accomplish. They do not have a cooling system and therefore heat is not exhausted/exchanged. Also, as stated, harmful gases are not separated.

Steam and oil/grease that rise up while you cook condense on the grease filters and are separately collected. The process usually involves the hot air changing its direction quickly and multiple times through the fine mesh filter or through the baffle filter thereby causing the steam and grease to condense and separate. The actual process depends on the kind of grease filters in place: mesh or baffle. To learn more about how a range hood functions, the many features and technical jargon to look out for, etc. I would suggest you take a look at my very detailed and helpful range hood buying guide.

Charcoal filters are used to trap odor. Unlike the grease filters, charcoal filters cannot be washed and they must be replaced. For most people, the main reason to install a range hood at home is to get rid of cooking odors and prevent it from spreading around the house. For everything else, many choose to keep a window open. Therefore, it’s important that I point out that charcoal filters are a necessity to get rid of the odor and depending on the use they may have to be changed every quarter or so. If you don’t cook a lot, you may have to replace it just once a year or even less. Therefore, if the ducting price is the main reason you are choosing a ductless hood, keep this in mind.

Benefits of Ductless vs Ducted Range Hoods

We’ve already seen the drawbacks of having a ductless hood, but there are some aspects where ventless hoods score better:

  • They are cheaper and easier to install.
  • There’s no need for venting and the setup of a makeup air system.
  • No heat loss during winters.
  • When you rent a place and are not allowed to create vents, they are an ideal option.

I have thoroughly reviewed some of the most popular ductless range hoods on the market. You should check them out. If you don't find the perfect one for your kitchen on my list, you would at least read the points I make which are important and to be kept in mind when picking a hood.