At least some insulation is required for ducts that run within the conditioned space of floors, walls and ceilings to ensure that the conditioned air is delivered at the required temperature and also to prevent condensation on the outside of the duct walls. Ducts within conditioned spaces will experience only minor conductive losses and gains as they are only exposed to indoor air temperatures. However, these ducts often require some insulation to prevent condensation on duct walls which can cause oxidation, corrosion, mold and mildew damage inside floor or ceiling cavities.
Condensation occurs when warm air strikes a cold surface such as a duct carrying cooled air from a central air conditioner. Warm air can carry more moisture than cold air. So when warm, moisture laden air comes in contact with the cold metal surface of the duct, the air will cool. Any excess moisture that the cooler air can no longer hold will condense into droplets. Once the water vapor becomes actual water, it not only oxidized the metal, but has the potential to drip and cause rot, mold and fungus growth that will degrade the surrounding building materials. Prodex Total, properly installed, will act as a vapor barrier and prevent condensation on the duct surfaces.
One of the biggest drawbacks of using fiberglass batt insulation is its vulnerability to moisture. When ducts experience condensation, moisture collects in the fiberglass, causing it to pack and lose its insulating value. In addition, during the wrapping process of insulation, the fiberglass is pulled tight around corners causing packing which interferes with the ability of the fiberglass to achieve full insulating R-value. Fiberglass batt insulation must be carefully installed and kept dry to maintain its stated R-value. The other major drawback of using fiberglass batt insulation is that it has no effect on radiant heat transfer. The difficulty of maintaining loft during installation, protecting against moisture, and preventing breathable fibers from coming into contact with workers have lead experts to recommend alternatives, such as Prodex Total to be used as duct wrap.
Prodex Total is installed with spacers so that the insulation installed sits away from the duct surface creating an air space both to reflect radiant energy and prevent moisture buildup. Prodex Total will also not compress on corners or have its R-value affected by moisture or humidity.