The Environmental Protection Agency recommends cleaning air ducts as needed. Although it does not encourage routine cleaning, it does encourage routine filter changes and yearly inspections of the heating and cooling system. After a remodeling project, it's wise to clean the sawdust out of the ducts.
Cleaning the air ducts might be necessary if anyone in the home or office is suffering from allergy flare-ups. Other indicators include visible mold, rodents or dirt escaping from the vents. If mold is suspected, it can be confirmed by a laboratory since some substances are similar in appearance to mold. If the system's heat is generated by burning fuel, it needs to be checked each fall or winter for carbon monoxide risk. When it is time to clean, it is important the company cleans all parts of the system and not just the ducts.
Cleaning air ducts cuts down on the amount of bacteria and mold within the system. It also reduces the dust sitting on the surface of return-air ducts, although its benefits for supply-air ducts are less tangible. The best method involves cleaning the fan on the air handler/furnace and the return-air ducts only.
Duct cleaning providers are not certified by the EPA, but consumers can check with local agencies to learn whether they are licensed. The EPA warns people to be wary of any duct cleaner who either claims the service provides health benefits or attempts to use chemicals. The agency also suggests contacting the references of duct cleaning professionals before hiring them.