Evaluating the potential efficacy of three antifungal sealants of duct liner and galvanized steel as used in HVAC systems

Abstract

Current recommendations for remediation of fiberglass duct materials contaminated with fungi specify complete removal, which can be extremely expensive, but in-place duct cleaning may not provide adequate protection from regrowth of fungal contamination. Therefore, a common practice in the duct-cleaning industry is the postcleaning use of antifungal surface coatings with the implication that they may contain or limit regrowth. However, even the proper use of these products has generally been discouraged because little research has been conducted on the effectiveness of most products as used in heating, ventilating, and air-conditioning (HVAC) systems. Three different coatings were evaluated on fiberglass duct liner (FGDL). Two of the three coatings were able to limit growth in the 3-month study; the third did not. One of the coatings that was able to limit growth was further evaluated in a comparison of FGDL or galvanized steel (GS) under conditions that mimicked their use in HVAC systems. The results showed that both moderately soiled and heavily soiled uncoated FGDL and GS duct material can support fungal growth, but that GS duct material was more readily cleaned. The use of an antifungal coating helped limit, but did not fully contain, regrowth on FGDL. No regrowth was detected on the coated GS