Fiberglass:“a material consisting of extremely fine glass fibers, used in making various products such as yarns, fabrics, insulators and structural objects or parts” The American Heritage Dictionary
Just as the name implies, fiberglass is composed of glass fibers thinner than a strand of hair which are then used in a wide array of products.
The fibers can then be woven into a mesh-like fabric and manufactured into the hardened material we usually see made into boats, spas, automobile panels, fishing poles, tools, structural components of every sort.
The list is endless. Or, left in its loose “fluffy” form, it is used to manufacture various forms of insulation such as blown-in attic insulation and duct wrap.
The type of fiberglass we are focusing on is the “fluffy” type used for thermal and acoustic insulating materials. You will see this to insulate attics and walls. And more specifically, the fiberglass used to insulate air conditioning equipment and ductwork
Loose blown-in fiberglass to insulate an attic space.
Fiberglass duct liner.
Fiberglass duct wrap.
An interesting side note, the term “Fiberglass” is actually trademarked by the Owens Corning Company, a major manufacturer of fiberglass products. Just like “Kleenex” or “Thermos”, both of which are trademarks owned by private corporations, these trademarked names have more recognition as the product itself than the actual name of the product does. In this case, Fiberglass is a trade name for “fibrous silicate glass”. You would likely get a quizzical look if you told someone you are going to Home Depot to get a roll of “fibrous silicate glass”!
Fiberglass is a highly effective form of thermal insulation. It is relatively inexpensive, easy to install and it does the job. If properly installed, it can last indefinitely. Fiberglass is equally effective in the field of acoustic insulation. Movie production houses, music schools, auditoriums and recording studios routinely use forms of fiberglass to reduce the transmission of sound in order to create the quiet environment so vital to these activities.
Fiberglass is the most commonly used material for insulating air conditioning systems. Usually, it is wrapped outside ductwork, but it is also used to line the interior surfaces of both air handling equipment and ductwork. Installed internally, it has a dual purpose - thermal insulation as well as acoustic insulation. Without the muffling properties provided by the fiberglass, the noise of the equipment and air flow would come through the vents which can be pretty annoying. Further, in ductwork that is exposed to the weather, such as on a roof, the insulation will be installed on the interior the the metal ductwork to protect the insulation itself from the elements.
Microscopic view of fiberglass.
Viewed under a microscope, fiberglass insulation is actually composed of more air than of fibers. It is this combination of the glass fibers and the air pockets that provide the insulating factors that make it so effective for both thermal and acoustic insulation.
So what does all this have to do with duct cleaning?
A lot, as it turns out. In our experience, Fiberglass is probably the number one issue that effects the clean, efficient operation of an A/C system. It isn’t the fact of the fiberglass, but what happens when fiberglass has become saturated, was improperly installed or damaged in some way. Or mold has begun to grow on the surface or it’s begun to fall apart.
These situations can lead to many things that degrade the air quality as well as the efficiency of a system.
There's more, but this covers the main things we see on a regular basis and they all vary in severity.
So when the fiberglass insulation gets into a condition where it is shedding fibers or when it is so dirty that it has become a luxuriant mold garden, it is time to act. Well, actually the time to act has probably come long before you noticed it.
In its standard specification and guidelines, NADCA (National Air Duct Cleaner's Association), states the following regarding the restoration of fiberglass materials in HVAC systems:
"4.17 Removal of Mold Contaminated Porous Materials: It is recommended that porous materials with mold growth be properly removed and replaced."
Resurfacing or encapsulating can be done to create a protective outer surface of internal fiberglass insulation, however, NADCA further recommends the following:
"4.20 Damaged Fibrous Glass Material: When there is evidence of damage, deterioration, delaminating, friable material, such that cleaning or resurfacing cannot restore fibrous glass materials, replacement is recommended."
Does all of this mean that fiberglass is something to freak out over? Is it the next asbestos? Is its presence a sure sign of poor indoor air quality? No, no and no.
If it has been properly installed, inspected on occasion and repaired where necessary, in our opinion it does not pose a hazard, particularly if it is coated or covered to protect the surface and reduce the introduction of fibers into the air stream. But as soon as the material is falling apart, damaged, saturated or showing evidence of mold growth, it must be addressed. No “band-aid” half-way remedies will do.
Here are a few stable road markers:
The bottom line is that today, fiberglass continues to be the go to insulating material for A/C systems. Whether one agrees with using it or has concerns about its presence, you will find it in almost every system you come across. That it is there does not mean it has to be replaced without question - possibly ICUs, clean room type situations, certain manufacturing areas and other sensitive environments will be better off with a non-fiberglass solution, but in most situations, it will be OK.
But remember. Fiberglass is NOT an "install it and forget it" solution. The binders will break down over time; the material is subject to erosion when saturated and it does damage rather easily. In these cases, it will become a source of problems both in terms of indoor air quality as well as efficient operation of the systems.
It can be expensive to handle a fiberglass problem, whether it is moldy or simply falling apart. So if you are going use it, the best preventative maintenance solution is to ensure it is installed properly in the first place! And if you need to repair or replace the liner, make sure the company doing it knows what they are doing! Do so and it will last you for years.
Until next time!