How We Clean Air Ducts

Published on: June 13, 2013

In a coordinated effort between federal, state and local governments, national building code standards have repeatedly been revised to improve the energy efficiency of both residential and commercial inhabitable structures. Advances in building science allow architects and engineers to evaluate the impact of a variety of different materials and construction techniques on the total efficiency of the building. This includes windows, doors, duct leakage, insulation, perimeter tightness and local climate conditions.

While the overall energy consumption of a modern home or office has been reduced substantially, these improvements have also negatively impacted the indoor air quality (IAQ) in a typical building.

The Scope of the Problem

Everyday activities generate a multitude of indoor contaminants including dust, debris, animal dander, mold, fungi and other particulate matter. According to the EPA , the immediate effects of short-term exposure to indoor airborne irritants include headaches, dizziness, sore throat, and itchy eyes. While these symptoms can be treated, chronic exposure can cause heightened sensitivities that may worsen over time. If left unaddressed, long-term contact with certain biological and chemical pollutants can lead to a variety of serious health issues including respiratory diseases, cancer and heart disease.

Since individual physiology varies, it is difficult to identify the exact concentration levels and exposure limits required to produce specific health issues. However, medical professionals generally agree that a building with a low concentration of ultra-fine contaminants will provide a significant health benefit to the occupants.

The Advantages of Clean Ductwork

The importance of maintaining a building’s air distribution system can not be overestimated. In a comprehensive report on duct cleaning published by the Florida International University Department of Construction Management, researchers presented the following conclusions on the effectiveness of the cleaning process:

  • “Duct cleaning improves the indoor air quality of residential buildings. Residents of the two houses selected for the phase II study reported to the investigators that they felt much better physically after duct cleaning that was done in the phase I study.”
  • “Long-term effects of duct cleaning on viable bio-aerosols, as indicated in the Phase II results, suggest that the effect of cleaning lasts a long time.”
  • “We suggest, as we did in the Phase I report, that cleaning of HVAC systems and ductwork should be performed by professional duct cleaning specialists.”

While clean air ducts can help keep the indoor environment safe and healthy, regular duct cleaning offers several other benefits that can improve indoor comfort and save substantially on equipment costs and monthly operating expenses.

  • Reduced Fuel Consumption: Dust, dirt, and other pollutants can seriously degrade the performance of the HVAC equipment. When grime builds up on the evaporator coil, the efficiency of the heat transfer process is seriously compromised. Obstructions and impediments in the ductwork increase friction loss and reduce airflow. In either instance, the system must work harder to meet the thermostat call.
  • Eliminate Odors: The presence of established mold or fungi colonies in a duct system can introduce unpleasant odors into the indoor environment. Even without the presence of biological organisms, older air ducts can often release a musty or sweaty aroma. Regular cleaning of the ductwork will leave the indoor air smelling clean and fresh.
  • Extended Equipment Life: The majority of HVAC equipment failures are caused by improper maintenance and a buildup of particulate matter in the air distribution system. When the airflow is restricted, and thermal transfer efficiency is degraded by a dirty evaporator coil, the system must work longer and harder to meet the indoor load requirements. This performance reduction will place additional stress on other components and may shorten the service life of the equipment.

Duct Cleaning Procedures

In order to enjoy the benefits of clean air ducts, it is important to select a dealer who conforms to the standards outlined by the National Air Duct Cleaners Association (NADCA). The contractors affiliated with AC Southeast® adhere to strict protocols that includes the following elements:

  • The Inspection Phase: The inspection phase is a critical first step in determining the need and scope of the required cleaning services.
  • Developing Work Plans: A detailed work plan outlines the specific tasks that will be completed during the cleaning process.
  • Establishing Engineering Controls: Engineering controls are required to ensure that workers are protected from potential chemical and biological hazards. Onsite operating procedures are established to prevent potential cross contamination in the HVAC system and different rooms in the building.
  • Cleaning and Restoration Guidelines. Cleaning measures used on the job should meet or exceed the guidelines outlined under the scope of work provisions in the contract.
  • Verification Methodology: After the process is complete, the cleanliness of the system should be confirmed through visual inspection and quantified testing if necessary.

The Duct Cleaning Process

As an industry, duct cleaning evolved because of the need to remove contaminants from inaccessible areas inside a central HVAC system. Common components that are serviced include the air ducts, heat exchanger, air handler, evaporator coil, fan motor, plenum and the housings.

Every system is thoroughly cleaned and sanitized to improve system performance and minimize the likelihood of future mold and fungi growth. The contractors on our website develop a targeted plan for every job that includes the following comprehensive procedures:

  • The supply and return sides of the heating and air conditioning system are isolated, so they can be cleaned separately.
  • The return side is evaluated, and a strategically placed access hole is cut into the ductwork. The vacuum hose is connected to the duct by a collar.
  • Once the vacuum is engaged, the farthest return air grille is removed, and a compressed air whip is used to loosen any debris adhered to the duct surface. The process is repeated at each grille as the technician works back to the original access point. After the branches are cleaned, the tech will finish with the plenum and main return trunk.
  • When the return side is completed, the vacuum hose is removed, and an access hole is cut into the supply side of the system. All of the supply registers are taped off, and the vacuum is turned on after the hose is attached to the collar. The entire supply side of the air distribution network is placed under an extreme negative pressure. The technician will then clean the air ducts one branch at a time, starting with the farthest register and working back to the access point. Stubborn debris is agitated by compressed air and blown back toward the vacuum.
  • After the registers and supply branch run-outs have been cleaned, the main trunk line is addressed by using a combination of compressed air and mechanical brushes.
  • The technician will make a thorough inspection of the air ducts before disconnecting the vacuum. At that point, all critical system components can be air washed to improve performance and efficiency. At the customer’s request, the ductwork can be sanitized with an aerosol spray that contains a biocide to inhibit the growth of undesirable organisms.
  • When the cleaning process is finished, the technician will cover and seal the duct access holes to prevent potential leakage. The same holes can be used the next time a cleaning appointment is scheduled.

Duct cleaning is appropriate for bare metal, flex duct and insulated duct systems . Qualified contractors have a variety of tools specifically designed for each application that will not damage or breech the duct material.

A Total IAQ Strategy

Once the ductwork has been cleaned and sanitized, it is important to incorporate ventilation, humidification, filtration and eradication into a comprehensive indoor air quality strategy.

  • Ventilation: Mechanical ventilators are designed to address air quality issues resulting from buildings with tight perimeters. A ventilation device introduces a measured amount of fresh air into the living area while the same volume of indoor air is exhausted outdoors. Models with energy recovery features recapture a portion of the energy that is lost during the air exchange process.
  • Humidification: Proper humidity control is an important part of a healthy indoor environment. Air that is too dry allows ultra-fine particles and microscopic organisms to remain airborne where they can be easily transported from room to room. A fine-mist or steam humidifier can help maintain a consistent humidity level throughout the building.
  • Filtration: The efficiency of a central HVAC system filter is determined by its MERV rating, which is a measurement of the volume of particulate matter trapped by the filter over a given period of time. Cheap fiberglass filters only remove visible impurities like hair and dust. Electronic air cleaners and advanced media filters can capture up to 90 percent of air borne pollutants under 1 micron in diameter. This includes smoke, pollen, dander, mold spores and certain gasses.
  • Eradication: Some biological organisms, including mold and fungi, tend to thrive in environments where moisture and dust are present. Condensation is usually abundant at the evaporator coil in a central HVAC system. A germicidal UV lamp installed inside the A-coil will kill a variety of contaminants including viruses, bacteria, mold spores and fungi. UV light will effectively sterilize the interior of the air handler.

Complete IAQ Services

For customers living in Mississippi, South Carolina, Georgia, Florida and Alabama, AC Southeast® is your authoritative source for complete IAQ information and contractor referrals. Our industry affiliations include the most trusted names in the HVAC industry, and our endorsement is your guarantee that the contractor’s work will always be completed in an accurate and timely manner.