Should I Fog or "Sanitize" My Ducts? - Short #220 · HVAC School - For Techs, By Techs summary

Key takeaways

Fogging ducts is mostly ineffective and should only be used as a last resort.
Residual chemicals from fogging can promote mold growth and may be harmful to sensitive individuals.
Physical cleaning methods can be more effective than fogging in ensuring clean and safe duct systems.
Understanding product labels and proper application is crucial for any chemical use in duct cleaning.
Professional assessment is important before deciding to fog duct systems, especially in cases of suspected microbial growth.

Summary

The Efficacy of Fogging Ducts

In this segment, the hosts, Bryan and Zach, discuss whether fogging or sanitizing duct systems is effective. Bryan emphasizes that adding chemicals to duct systems should be a last resort and notes potential issues with fogging, especially on porous materials like internal-lined ducts or duct boards. They point out that the chemical residue left behind can actually encourage mold growth rather than eliminating it. Bryan suggests that without proper execution, fogging often leads to more problems than solutions, making a compelling case for thorough cleaning or even duct replacement when microbial growth is suspected.

Health Risks and Precautions in Fogging

The hosts highlight the health risks associated with chemical fogging, particularly for sensitive individuals who may react adversely to the chemicals used. Choosing fogging should be based on informed decisions regarding potential health risks against uncertain benefits. Bryan reminds listeners that proper understanding of product application is crucial, and users should always read the labels to avoid creating adverse conditions in the ductwork.

Fogging vs. Physical Cleaning Methods

A comparison of fogging versus physical cleaning methods is discussed extensively. Bryan shares his experiences using traditional cleaning methods, like using a whiffle ball with rags to thoroughly clean ducts instead of relying solely on chemicals. He articulates the importance of seeing tangible results from cleaning efforts, suggesting that cleaning processes should effectively remove contaminants, not just `cover them up` with chemicals. Bryan draws parallels between duct cleaning and line flushes to emphasize the necessity for visible results.

Conclusion and General Recommendations

To conclude, Bryan underlines that fogging should not be the go-to solution for duct sanitation. Instead, it should be reserved for specific cases, such as confirmed mold issues, where a strategic decision has been made based on professional assessments. Moreover, Bryan contrasts fogging with processes like aero-seal, clarifying that the latter serves a different purpose by sealing leaks rather than sanitizing ducts.

Show notes

In this short podcast episode, Zach joins Bryan to answer a common duct maintenance question: Should I fog or sanitize my ducts?

The National Air Duct Cleaners Association (NADCA) outlines the uses of chemical products. Adding chemicals is usually a last resort in flex or sheet metal (externally wrapped) duct systems; they should NOT be used on ducts with internal liners or are made of duct board or any other material with porous surfaces.

Fog is typically applied while a vacuum is running at the opposite end of the duct. It liquefies on surfaces, and a lot of contractors don't go in and dry off the duct surfaces. It's difficult to coat the entire interior of a duct system with the chemical to make it as effective as possible, and the residue creates a moist, sticky film that actually encourages microbial growth in the ductwork. On top of that, some people may be sensitive to the chemicals.

In many cases, replacing ductwork that has been confirmed to have microbial growth is more reliable. Chemical duct sanitation often has more of a perceived benefit than long-term results. The use of chemical cleaners in ductwork is similar to that of using some line set flushes without forcing a solid pig through the line set to pick up the residue afterward. Ultimately, the customer has to make an informed decision based on the problem and knowledge of the benefits and drawbacks of chemical solutions.

NADCA's white papers, including "Chemical Product Applications in HVAC Systems," are available at https://nadca.com/industry-professionals/nadca-white-papers.

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Should I Fog or "Sanitize" My Ducts? - Short #220