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What is Duct Cleaning, what does it entail, and how is it performed properly?

Duct cleaning (aka HVAC cleaning or HVAC remediation) can help you improve and maintain healthy air quality in your home or at your business. Many companies advertise low cost introductory offers for duct cleaning services. But how effective is their service? Does it provide the level of cleanliness and quality of service that you need? Read below to learn more about the best practices and industry standards of care for duct cleaning.

At RTS Environmental Services we specialize in providing duct cleaning services that exceed the National Air Duct Cleaners Association (NADCA) ACR (Assessment, cleaning, and restoration) standards.

Duct cleaning is an important process because it removes common dust, pollen, mold spores, mildew, algae, bacteria, construction materials, fiberglass, skin flakes, and live & dead insects when they accumulate beyond normal ecology levels. These irritants affect not only the health of occupants but the health of the building itself. If the air is dirty, then the building that surrounds the air can become adversely affected and dirty too. According to NADCA ACR, “If dirt accumulates in ductwork and if the relative humidity reaches the dewpoint (so that condensation occurs), then the nutrients and moisture may support the growth of micro biologicals.”

Filtration is a critical component of a healthy HVAC system. But even if filters are replaced, there are other areas where these biologicals can become trapped or collect. One particular area is the return manifold, where air is pulled into the system to be reconditioned and recirculated through the home. Depending on how the HVAC system is configured, these biologicals can collect and cause health issues. Some examples include:

  • Flexible ducting: Despite the pitfalls, flexible ducting is being used more and more due to its ease of installation and low cost. Due to the nature of how flexible duct is manufactured, it collects dust much faster than fixed sheet metal ducting. Flexible duct is also less efficient when pressurized than sheet metal duct and poses risks in condensation and moisture collecting inside the ducts at low points.
  • Sound insulation inside ductwork: Sound transmission and thermal insulation are used inside many ducts in condos and larger complexes. Unfortunately, these insulations collect dusts because they are fibrous. They are difficult and nearly impossible to clean. And because they are often installed at the factory with spray adhesive, they are not easily removed without removing and replacing the ducting itself.
  • Roof mounted air handlers: Due to difficulty in access, outdoor units are often neglected as opposed to indoor units. Filters are not changed as often as they should be and the air handler is subjected to the extremes of the outdoors. High temperature and high relative humidity combined with dirty filters can create an environment inside the HVAC for mold to grow rapidly.
  • Evaporator core configuration: Evaporator cores are often a hidden but critical element of every HVAC system. Usually located above the air handler fan, the evap. core is responsible for adjusting the temperature of the air that flows through it. A tightly packed set of metal fins with coils, the evap. core is a sensitive component. When cooling, the byproduct of the coils hitting dew point is condensation. This condensation moves down and into a drain pan. If this drain pan does not allow for removal of the condensate water in a timely manner, it can create an environment for mold growth on the coils and surrounding components.

HVAC systems can be complicated and every system is unique. So how is duct cleaning to be approached? NADCA Best Practices include:

  • HVAC system inspection and assessment: A proper inspection of the system prior to the cleaning is important. Visual inspection of the ducts to include the return and supply ducts, their material, and the air handler configuration should be documented to ensure that they are cleaned properly later and occupants are safe.
  • The day of the work: Occupants should consider evacuating the building to prevent exposure to dust and cleaning products.
  • The air handler should not be used as a tool for cleaning the ducts. The air handler should be sealed off and protected for its own cleaning process.
  • Negative air pressures used during the cleaning process should be vented to the outdoors.
  • Ductwork access ports should be well sealed following the completion of work. When creating access into sheet metal ducts, it is important to also be aware of any insulation, especially fiberglass, to ensure it is not dispersed into the system.
  • High Cubic Feet Per Minute (CFM) does not necessarily mean that the duct cleaning is more effective. High CFM negative air pressure is only one part of the equation for effective duct cleaning. If you see this advertised, be sure to ask about how the dusts will be disturbed and removed from the surface of the duct work.
  • HEPA (High efficiency particulate air) vacuums should be used to clean the accessible areas of the ductwork including the supply diffusers, and return diffusers and manifolds.
  • Biocides should only be used when approved by the EPA and designed for use within HVAC systems. Biocides are not an effective solution within themselves to clean an HVAC system. Do not rely on fogging to get the job done as this is only effective for a short period after dispersal of the chemical agent.
  • Cleaning and sanitizing of the air handler and evaporator core are important. Once cleaned, these components should be effectively dried to ensure no moisture remains, potentially damaging components and exposing occupants to biocides.
  • Where mold remediation occurs, the HVAC system should be isolated and protected from remedial activity.
  • Once the system is remediated, a plan should be put into place to ensure proper maintenance and cleaning moving forward.

Following these best practices and understanding common pitfalls to HVAC systems is critical to ensuring a successful duct cleaning. Value oriented duct cleaning may not be the best value if performed improperly!

If you want to learn more about how we approach duct cleaning, please call us at 800-722-5589.

Also see the NADCA ACR Standard and Industry Guideline: https://nadca.com/system/files/ascs_to_the_acr_standard_manual_1.pdf