Clean and Repair for Health Issues

• Cleaning furnace ducts has not been shown to prevent health problems. On the other hand, homeowners should consider having ducts cleaned under certain circumstances. One is the presence of visible and substantial mold growth inside the duct hard surface such as sheet metal. The only way to be certain mold is the issue is by having it analyzed in a laboratory. If it is present, ducts should be cleaned or possibly replaced. The underlying problem that enabled mold to enter and grow should be addressed. Otherwise, the mold will recur.
  
  If ducts have an infestation of rodents or insects, they could also benefit from cleaning, but as with mold, the underlying problem that is enabling the infestation must be addressed or the vermin will return.
  
  

Duct Cleaning and Furnace Efficiency Are Unrelated

• The act of cleaning heating and cooling system components such as fans, cooling coils and heat exchangers has some potential to improve the efficiency of the heating system and prolong its life cycle. This, in turn, can result in cost savings for the homeowner. Virtually no evidence stands in support of cleaning ducts toward improving system efficiency.
  
  

Evaluate Use of Sealants and Biocides Carefully

• Under some circumstances, using sealants and biocides to treat furnace ducts could be appropriate, but according to the U.S. Environmental Protection Agency as of March 2011, "Research has not demonstrated their effectiveness in duct cleaning or their potential adverse health effects. No chemical biocides are currently registered by EPA for use in internally-insulated air duct systems."
  
  

Clean the Air Without Cleaning the Ducts

• One of the dangers of cleaning furnace ducts is causing unintentional damage to the ducts. A number of techniques help limit household air contaminants without disturbing furnace ducts. One is to vacuum areas with visible dust collection by employing a HEPA vacuum cleaner and using the highest-efficiency vacuum cleaner bags fitted for it. Using a filtered vacuum with filtered bags helps limit the amount of the dust that escapes into the air. When installing a new air filter in the heating and cooling system, use the highest-rated filter for efficiency that the manufacturer recommends. Change the filter at least as often as the manufacturer recommends. For systems that include a humidifying component, operate within manufacturer guidelines and arrange for service immediately if any leaks or water damage become evident.