Ductless range hoods are hoods that are have no duct work to evacuate the smoke and steam to the outside of the home. Using a ventless range hood is cost effective but compromises on the smoke and steam evacuation.
Ductless range hoods are most commonly seen in two basic types; in a microwave/exhaust hood combo, or an under-cabinet mount. The under-cabinet mount is the least expensive. The microwave style is good at accomplishing, be it at a diminished capacity, both microwave cooking and a ventless range hood.
The duty of range hoods is to shine light down on the cooking surface and also remove cooking pollutants from the indoor air. Ductless hoods do provide light but do not remove steam, and are somewhat efficient at removing smoke and cooking odors.
There is another type of range hood filter as well. It's a mesh type filter with no charcoal. These are the least efficient and does a lackluster job of doing any filtering. I do not recommend this type of filter. But they are easily cleaned and are reusable.
The CFM of the fan can be lower with a ductless range hood. The reason for this is the fact that the air is simply recirculated into the room. A guideline for this is 100 CFM, or more, per burner.
The Sone rating is the measurement of sound from the range hood. The lower the numbers the lower the sound emanated from the hood. The lower the sound the more likely you will be to use the hood, and without the annoyance of a loud fan.
Steam is not removed by ductless range hoods. The steam is simply recirculated into the home. This can be a downfall of this type of hood. Without having the excess moisture vented to the outside, a window may need to be opened to solve this problem. In the winter months when the humidity is very low, the extra moisture may be beneficial.
Be sure to check my other pages on range hoods. There are other hoods you might like.
Ventless range hoods may not be code approved in your area. It is a good idea to check with your local building department to determine this. Some codes require venting to the exterior of your home, and there may be specific electrical requirements as well.
The best thing about these hoods is the price. These hoods are relatively inexpensive, some for under $50. If you do not cook often or do not want to go through the process of cutting a hole in side of your house, this style hood is an alternative.
Also by not having a hole in the side of your house this will help you save on energy. How? By not letting heated or cooled air in or out of your home. With the ducted type hood there will always be an area exposed to the elements, and the possibility of letting your conditioned air out of your house.
Overall I think these are not a bad idea. They do have some downsides, but also has some positives. It's a personal decision and when taking these prior points into consideration it will also be a functional one.
When compared to a vented type hood, the cost of a ductless hood can be 1/10 the price. Some serious consideration needs to be done when comparing the ductless to ducted types of range hoods. Both have their advantages and the price reflects this. The vented type can be expensive.