Heavy usage of the heating and cooling system could necessitate more regular cleaning. If you notice that your furnace air filter is excessively dirty after one month, it's a good sign you should consider more frequesnt duct cleaning to remove buildup from the HVAC system.

The frequency with which you should clean your home's air ducts can vary based on several factors, including:

Allergies

If you or someone in the household has allergies or respirtory issues, you may want to have the ducts cleaned more frequently.

Pets

Homes with pets may need to have the ducts cleaned more often due to pet hair and dander.

Smoking

A household where smoking occurs will require more frequent cleanings.

Home Renovations

If your home has recently been renovated—especially if there was asbestos abatement, lead paint removal, or significant dust—your air ducts should be cleaned.

Dry Climate

Homes in drier climates may need more frequent duct cleaning to prevent airbourne particles from circulating in the air.

New Home or New HVAC System

If you've just moved into a new home or installed a new HVAC system, it's advisable to check and possibly clean the ductwork.

As a general guideline, the National Air Duct Cleaners Association (NADCA) suggests having your air ducts inspected every two years to assess the need for cleaning. Some experts recommend cleaning every 3-5 years, but this can vary based on the factors listed above.

If you notice signs like a musty or moldy smell when the HVAC system is running, visible mold inside the ducts, or an excessive amount of dust and debris, it may be time for a cleaning regardless of the last scheduled service.