A number of local carpet cleaning companies have ventured into the "duct cleaning" business. They promise clean ducts, free of dust and allergens, after utilizing any one of several duct cleaning "methods." However, these processes typically leave the ductwork only partially clean and often cause damage to fragile ductwork that has become weak after several years of exposure to 140°+ attic temperatures. In our opinion, there is a logical reason why fire restoration companies often insist in replacing all of the flexible ductwork in homes where air conditioning systems have distributed smoke during a fire; duct cleaning methods can't provide a thorough cleaning.

Steel ductwork, with no internal insulation, provides for the best duct cleaning results because the interior of the duct is smooth, and lacks the numerous grooves and folds found in plastic ductwork. In addition to making cleaning easier, the smooth interior of metal duct is also more resistant to mold and mildew growth and dust accumulation. However, most residential systems are built with flexible ductwork because of its reduced cost and ease of installation. If you are considering having your ducts cleaned, ask Nash Mechanical for a complimentary quote to replace your existing duct work.

Metal duct, shown above, is usually wrapped externally with insulating "duct wrap." This minimizes the moisture that would otherwise condense on the exterior of the duct and, more importantly, keeps attic heat from transferring through the metal wall of the duct into the cool air flowing inside.

The "flex-duct" shown below consists of a plastic liner grouped with a metal coil that acts as a spring, keeping the duct from collapsing on itself. The exterior insulation wrap is contained by a "metalized plastic" covering that helps reflect heat. The inner spring creates grooves where dirt and mold often collects in older and neglected systems. Duct cleaning companies can't possibly clean this type of duct work thoroughly.

The duct shown to the left is an example of the previous generation of flex duct used in many residential systems. This type of flex-duct does not have the reflective covering; instead a heavy gray plastic is used to contain the insulation and provide a moisture barrier. In many attics where attic vents allow sunlight to enter the attic space, the UV rays breakdown this plastic covering. The covering often disintegrates when it is touched or moved, a common occurrence as homeowners move things around in the attic or as new systems are tied into existing ductwork.