The answer to 'when to replace duct cleaning' is that most experts recommend having your air ducts professionally cleaned every 3-5 years, depending on several factors. Duct cleaning is an important maintenance task that helps improve indoor air quality, energy efficiency, and the lifespan of your HVAC system.
The frequency of duct cleaning can vary based on factors like the age of your home, whether you have pets, if anyone in your home has allergies or asthma, and how often the HVAC system is used. Homes with more occupants, pets, or heavy HVAC usage may need more frequent duct cleaning, perhaps every 2-3 years. Older homes or those with significant dust buildup may also require more frequent cleaning.