IAQ Website of the Month

Get your Ducts in a Row

Each month we publish a newsletter titled IAQ Website of the Month.  The excerpt below was originally published in the June 2012 newsletter.

Air duct cleaning often gets a bad rap due to unscrupulous and unethical contractors. Abuses are often recorded on hidden camera, like this one from last year: Dateline NBC.

The National Air Duct Cleaners Association (NADCA) participated in the Dateline NBC exposée.  This association has some great resources, so I’m featuring them as the Website of the Month.

On the NADCA website, you can download a free copy of their showpiece standard: Assessment, Cleaning and Restoration of HVAC Systems. NADCA also produces a Checklist for Residential Consumers.  This checklist is designed to help residential consumers understand NADCA’s recommendations regarding the process of HVAC cleaning.

The document that I want to highlight is a new publication titled NADCA Position Paper on Chemical Product Applications in HVAC Systems.  This has been a huge issue in my opinion.  I find that the average air duct cleaner doesn’t understand the EPA antimicrobial rules and ends up misrepresenting chemical treatments.

Here are two great quotes from the document:

  • “At this time, the EPA has not accepted any disinfectant, sanitizer or fungicidal products for use in the ductwork of HVAC systems.”
  • “Coatings and sealants used as resurfacing and repair products that do not claim to kill microorganisms, and which claim only to prevent growth on or in the coating film, do not need to be registered by the EPA for use in ductwork.”

If you perform duct cleaning or just recommend it every now and then, you need to read this document.  I’m hoping it will clear up some of the confusion surrounding the use of different chemicals in the HVAC system. To read the position paper, click here.

As you search around the NADCA website, you’ll find some other free resources to expand your knowledge of duct cleaning. To visit this month’s featured website, click on this link: NADCA homepage.

To subscribe to this newsletter click the following link: IAQ Website of the Month.

To consult with Ian in the Chicagoland area, please visit this page: Air Quality Testing.

By Ian Cull

I'm I.A.N. the Indoor Air Nerd. I'm a speaker and consultant on indoor air quality issues. To learn more about me, click "about" at the top of this page.

5 replies on “Get your Ducts in a Row”

Hello Ian,
Thank you for your article, I beleive I anmfacing major issues with my HVAC duct system, My husband and I are condisering changing the whole AC/unit and duct system. Before we do so please let us know if it’s necessary. The test findings are as follows.
kids room Aspergillus/Penicillium 416 raw count 8780/m3 98.9%, Kitchen Aspergillus/Penicillium 15/ 320m3/ 56.45%
outdoor Aspergillus/Penicillium 16/ 340m3 / 16.3%
Curvularia 99/ 2100/ 57.7%

Please help

Yes, your count in the kid’s room is significantly higher than in the kitchen and outdoors. However, you need to determine why that is, before you replace the HVAC system. It may be a leaky window, and all the money you spend on a new HVAC system will be for naught. Has anyone visually identified mold in the HVAC system?

Let me know,

Thank you for you help Ian. We are in the process having someone come out and taking a look at the unit. We had the interior coils clean 2yrs ago, and it was filthy. The tech said there was bacteria in the unit. He did treat it with some sort of chemical, and asks us to go outside for about 5 minutes. Maybe the problem was worse than we thaught. By window leak do you mean in the hvca or regular window, there is only on in their room. I see no signs.

By leaky window, I mean a regular window and that the moisture and mold issue may be totally unrelated to the HVAC system.
You should get convincing proof that there is a mold problem in your HVAC system before you have it totally replaced.
Best of luck!

Your posts are so helpful. Thank you! I have a related question. We’re having our heat pumps replaced and will use the existing ducts. The ducts are old and need to be resealed though. I’m very chemically sensitive. The contractor says we need to use mastic to get a proper seal. They are willing to work with us to find, sample, and test a mastic that might work for me. Is there a duct mastic that doesn’t off gas VOCs and that a chemically sensitive person might be able to tolerate? Thank you!

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