Healthy Duct System & Healthy Indoor Air Quality


What is a healthy duct system?? What is not??

Let’s start with what is not a healthy duct system. Dirty air ducts are not healthy for occupants and may experience symptoms similar to allergies, including coughing, running nose, itchy eyes and sneezing. Dust, microbial growth and other contaminants can be trapped inside the air duct system.

Causes and solutions to this problem:

  • Improper return air for the system will cause the system to become dirtier than normal. The system is designed for the air to travel at a specific speed across the air filters and through the blower compartment and evaporator coil. When the air travels faster than designed through the filter the dirt bypasses the filter or goes right through it. Then the blower wheel gets dirty, the evaporator coil gets dirty and the ductwork gets dirty. Also with this occurring the drain line will fill up with sediment and has the potential of clogging and causing water damage.
    • The solution is to add proper return air filter grills to the system and have the blower wheel, evaporator coil cleaned and drain line flushed or replaced depending on how full of sediment it is. By adding more return air filter grills the speed of the air will decrease and the filters will do what they are designed to do.
  • Improperly installed ductwork will cause dirt to get trapped. Microbes love dirt in a dark moist environment. These microbes can cause respiratory illnesses in most people. The flex duct system may have deteriorating insulation causing the inside of the duct to sweat. It may also have excessive material with kinks and valleys trapping dirt.
    • The solution in some cases is to replace the duct system and properly install it per the MFG. recommendations. Some duct systems just need some adjustments by shortening the duct and properly hanging the duct eliminating the pinch points. This will also help with air flow issues.
  • An unsealed return chase can bring contaminants into your duct system. If the return chase is not sealed air can infiltrate through the wood framing and enter the duct system. This humid dirty air is unfiltered entering the system.
    • The solution is to run a flex duct in the chase and install a duct board box for the filter grill thus eliminating the infiltration.
  • Lack of IAQ products can also contribute to an unhealthy duct system.
    • One solution is to add a Media filter at the unit in the attic. It will have more filter surface area and can last up to a year depending on the home.
    • Second solution is to add a UV Light. The UV Light helps eliminate microbes from forming.
    • A third solution is to install an Air Scrubber. This product has many many benefits for better indoor air quality. It cleans, freshens and purifies the air. It helps reduce allergies and asthma symptoms.
    • A fourth solution is to have a Microbial fogging done. This kills all microbes in the duct system.


In conclusion for Healthy Indoor Air Quality consider your duct system and IAQ products for solutions.

If you want to learn more about indoor air quality and feel you have a need for your home please call 936-264-1133 or email to schedule an appointment or head over to our contact page.

Mention this blog post and receive 10% off any Indoor Air Quality Products or Services.

IAQ products

2022 © Carl’s Quality Cooling and Heating LLC


Get A Quote (936) 264-1133