The fan in the hood over your stove has a steel-mesh filter that traps airborne grease, preventing it from building up inside the exhaust duct (if one is present), or on the inside of the fan housing (if the range fan isn’t exhausted to the outside).

 

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If cleaned regularly, a ducted range fan won’t need any further maintenance other than cleaning the exterior surfaces of the hood.

Filter cleaning is even more important in hoods that aren’t ducted to the outdoors. In such cases, the filter is the only protection the house has against airborne grease.

The easiest way to clean the filter is to remove it from the hood and wash it in an automatic dishwasher. Folks who don’t have a dishwasher may clean the filter by immersing it completely in a pot of water and adding a generous amount of dishwashing liquid, or a small amount of automatic dishwasher detergent. (Using both shouldn’t be necessary.) Bring the pot to a boil, and then turn off the heat and leave the filter immersed in the solution overnight. The next day, remove the filter and rinse away any remaining residue with a strong spray of hot water.
 

Some range fans have a separate activated charcoal or carbon filter mounted behind the grease filter. In other hoods, both filters are combined into a single assembly. Carbon filters help to trap additional odors and grease, particularly in installations which are not vented to the outdoors.

Some manufacturers claim separate carbon/charcoal filters may be cleaned using soap and water. Other makers recommend replacing a dirty carbon filter. Check manufacturer recommendations; if no advice is available, replace the activated filter. Many home centers sell grease and carbon filter replacements costing less than $20 for popular, standard-size range hoods. Filters for commercial-grade range hoods are considerably more expensive.