Ducts on a forced-air furnace should be cleaned every three to five years if factors such as pets, smoking, home renovations and weather conditions have produced more dust in the home. In some cases, homeowners may choose to only clean ducts when debris, pests or mold affects the system.
Most contractors should offer to do an initial inspection to determine if duct cleaning is necessary. When cleaning ducts, professionals sweep the ducts of the furnace and clean the central system and coils. Homeowners can cut down on the amount of dust within the dusts by routinely vacuuming heating registers and vents on a monthly basis.