When installing a new range hood, it is best to keep a few things in mind. Your range hood installation will depend on your eating and cooking habits, the location of your kitchen in your house, the location of your cook-top in your kitchen, and the design of your kitchen.
How to Choose the Proper Size
A range hood should cover at least the full surface of the range or cook-top. This means that if your range is 30" wide, it is recommended that you purchase a 30" or wider range hood. Additionally, the depth of your range or cook-top should be taken into consideration. As a measure to ensure the cleanest air, a properly sized range hood should extend approximately 3" beyond the edge of the range or cook-top.
Vented/Ducted vs. Non-Vented/Ductless
Choosing between vented and non-vented range hoods hinges on a few considerations. Vented/Ducted range hoods have a duct that takes the air outside through a vent. Non-Vented range hoods are also known as Recirculating because they take the air through a filter and re-circulate it back into the kitchen. Non-Vented Range Hoods can have a recirculating duct that has the filter inside, or they can be ductless. People choose this option when they have a wall mount application, but don't want to install all the ducting involved. Recirculating Range Hoods are a bit higher maintenance because you will need to occasionally clean or replace the filter in order for the air to actually be cleaned.
Your cooking and eating habits make a difference between which style to choose. If you regularly cook with oil or grease, cook food that leaves an odor, or cook things that produce a lot of smoke, it is best to get a vented/ducted range hood because it takes the oil, grease, odors, and smoke out of the house entirely. Otherwise, the non-vented/ductless option will suffice when filtering and recirculating the air.
The location of your kitchen and of the range in your kitchen makes a difference as well. If your range or cook-top is located on the edge of your kitchen, near an outside wall, it is possible to install a vented range hood that moves the air out of a vent in the wall. However, if the range is part of an island or the kitchen is surrounded by other rooms, the best route for venting the air is up and out the roof.
In either case, opting for a vented range hood will generally be more expensive due to the cost of installing the venting as well as the range hood itself. Purchasing a lower priced ventless/recirculating model is always an option if you are working on a tight budget.
If you do decide to go on the economical side, make sure you are getting what you'll need. For example, installing a non-vented/ductless range hood may save money, but you may also find later that you aren't getting the total ventilation your cooking really needs. Having to purchase another range hood, this time vented, and going through the installation process will certainly cost more than your initial savings.
How Far Above the Cook-Top Should it be Located?
It is preferable for the range hood to be located anywhere between 20 inches and 24 inches above the range or cook-top. In order to prevent harmful grease, oil, smoke, or gases from escaping into the kitchen for you and your family to inhale, it is best not to place the range hood much higher than this unless recommended by the installation guide for that individual product.
Depending on the CFM (cubic feet per minute of air vented), you may be able to get away with a range hood placed higher for aesthetic purposes.