Carolyn Christensen of Ductz of Greater Atlanta spoke to CAAG members about the ways that mold can grow in duct systems, and gave advice that HVACR contractors can give to customers with moldy ducts.

SAVANNAH, Ga. - Mold is everywhere, and for the most part it does not pose a health risk to building occupants. The job of a duct cleaning specialist is to ensure that even the slightest chance of a health risk due to mold in a building’s ductwork is minimized or eliminated. That’s where the HVACR contractor with a trained staff of professionals can make a difference to their regular customers and many other prospective customers - all of whom have a genuine concern for IAQ.

Carolyn Christensen of Ductz of Greater Atlanta recently spoke to members of the Conditioned Air Association of Georgia Inc. (CAAG) during the group’s annual conference in Savannah. Christensen gave some examples of where mold can be found in the ductwork and how trained technicians can thoroughly clean and disinfect ductwork during routine service calls.

She said her company gets a lot of calls for ductwork cleaning immediately after a home is built - something that HVACR contractors should be aware of. “Unless the vents are completely protected during the construction process, there can be a lot of debris in the ductwork and lots of places for mold to grow,” she said.

A lot of new homes use flex duct, which can make for an inviting home for debris. “The debris lies in the low spots and when the system is pressurized or depressurized, the debris rises up and blows around, then settles back in the low spots,” she said.

Putting more safeguards in place may cost builders a little more, and Christensen joked that she is “probably not very popular with builders because of the added cost to protect ductwork.”


Christensen gave some pointers for talking with customers about possible mold contamination. Besides educating them on which molds may be harmful, she advised that contractors never actually use the word mold. “I generally don’t mention the word because it might scare the customers,” she said. “I think of a substitute, like microbiological contamination.”

One of the definite no-nos in cleaning mold is to use a sanitizer on a porous surface, Christensen said. “It only cleans the surface and not what is below - and it leaves the surface damp, too,” she said. “Never introduce chemicals into ductwork unless it is absolutely necessary.” One of the solutions her company uses is to insert a patented foil lining in the ductwork to prevent mold from growing - and recommend the installation of coated ductwork.

To keep debris from infiltration, the most obvious solution is to properly seal the ductwork. Whatever is in a crawlspace or attic can be drawn into ductwork through cracks and improperly sealed joints. Christensen said that HVAC system installers could also be blamed for problems because the boots connecting ductwork and vents are often improperly installed due to poor hole cutting.

When inspecting a vent, especially floor vents whose horizontal surface attracts a lot of debris, Christensen adamantly said, “Wear gloves!”

She also talked about another breeding ground for mold: dirty evaporator coils. What contractors should do, she suggested, is talk about the benefits of a clean coil with customers. “It seems that people are more concerned about energy and the cost of operation than with a dirty coil,” she said. “But a dirty coil, besides being a source of mold contamination, affects a system’s efficiency.”

Christensen recommended several organizations whose members are well-qualified to inspect and clean mold, including the National Air Duct Cleaners Association (NADCA), the Air Conditioning Contractors of America (ACCA), the Indoor Air Quality Association (IAQA), and CAAG.

Publication date:05/26/2008