Just because you don't see inside your ducts – doesn't mean you don't breathe what comes out of them. Duct systems should typically be cleaned every 2 to 3 years.
Reasons to consider more frequent cleanings would include:
• People with allergies or asthma
• If there is a smoker in the household
• Hair and dander from loving pets
• Water or smoke contamination to the home
• If you have done any renovations or remodeling
• Purchasing an existing home