Technical Corner: When to Replace HVAC Insulation Pt. 2

Part 2 of “Technical Corner: When to Replace HVAC Insulation”

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During the life of the insulation, literally millions of cubic feet of air are passed through the AHU daily.  Air contains small particulate matter, the majority of which is below the limits of human visibility.  Air contains  ordinary dirt particles, and  microbial spores such as bacterial or fungal spores.  It is normal that these particulates impinge upon and get entrapped within the insulation.

When microbial spores impact the insulation, they often grow and amplify within the insulation itself.  This results in VOC emissions (odors) and a source of contamination for the rest of the air handler.

It is unfortunate that fiberglass cannot be cleaned or sanitized to help remove embedded microbes.  This is due to the nature of the fiberglass itself.

A workable solution to prevent fiberglass emissions and at the same time eliminate the potential for embedded microbes is to coat the surfaces of insulation.

Flex Seal ™ first brought on the market in the 1990s, was developed by our firm to address typical fiberglass insulation problems.

FIex Seal is applied using a professional  airless sprayer.   The coating of the insulation is done in place within the air handler, and takes a minimal amount of time.

A flexible white surface is obtained that is easily cleanable with a rag or brush.  This allows for the user to maintain the cleanliness of interior surfaces.

Flex Seal contains an antimicrobial to prevent  attack of microbes on its surface while controlling odors.   Drying time of the application is on the order of 3 to 5 hours depending upon temperatures and humidty.

Since most materials for duct construction are required to meet NFPA (National Fire Protection Association) 90A fire codes, Flex Seal has been engineered to surpass any and all fire/smoke requirements in the US or foreign countries.  ASTM tests show Flex Seal to have a Flame spread of zero, insuring full compliance with codes.

We recommend delaminated or heavily contaminated insulation be removed and replaced, and then recoated with Flex Seal.

Existing fiberglass insulation that still has its integrity and is not heavily contaminated should be coated to insure cleanabilty and prevention of fiberglass emissions.

What are your experiences, please let us know in the comment section below.

Lynn Burkhart is the founder and president of Controlled Release Technologies, Inc. located in Shelby, North Carolina. More information about the company, and its products, can be found at and by calling (800) 766-9057.

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