Range hoods without vents use a charcoal filter to remove odors and grease from the air before recirculating it back into the room while hoods with vents exhaust the air to the outside. Both types of hoods protect the kitchen from grease buildup.
When installing vented range hoods, it is essential that the duct reaches the outside the house. Without this precaution, the grease the vent moves out of the kitchen builds up in the space, creating a fire hazard. If outdoor venting is not possible, a hood without a vent makes a better choice.
When purchasing a vented range hood, consumers should pay close attention to the amount of air it moves in cubic feet per minute and its loudness in sones. Vents that move larger volumes of air are more effective at removing odors from the kitchen, but also remove heated air or air conditioning. Loud vents interfere with conversations in the area. Vent-free kitchen hoods do not provide these ratings on the package.
Vented range hoods have a grease filter that requires monthly cleaning using hand dishwashing detergent and hot water. Homeowners should replace damaged grease filters. The charcoal filter on ventless range hoods is not washable and requires replacement when dirty. If the vent operates slowly, the user should check the filter to see if it requires cleaning or replacement.