Aerosol Duct Sealing A retrofit method for sealing existing HVAC ducts  Many homeowners may feel that their money is flying right out of their windows, but it may actually be their ductwork that is to blame. An estimated 15 to 30 percent of a home's total heating and cooling energy is lost through leaky ductwork, costing consumers about $5 billion dollars annually. Lawrence Berkeley National Laboratory has developed a method for internally sealing heating and cooling ducts using a pressurized aerosol sealant. Aerosol duct sealing can reduce duct leakage by up to 90%, reduce energy use by up to 30%. It can also be used on existing homes without moving attic insulation or removing wall and ceiling finishes to gain access to ducts.
Aerosol duct sealing forces vinyl acetate adhesive particles into heating and cooling duct systems via specialized equipment. The adhesive particles are kept suspended by the airflow until they naturally try to exit the duct system through leaks. In the process, particles are flung against the holes where they adhere and build up until the leak is closed. Savings tend to be greater when air ducts pass through space outside the insulation envelope, such as through attics or crawlspaces. 
 | By reducing monthy energy costs, Aeroseal Duct Sealing can contribute to affordability. |  | By sealing a common source of energy loss in homes, Aeroseal Duct Sealing contributes to home energy efficiency. Energy savings will depend on the leakiness of the original ductwork, the location of the ducts, and the climate. |
Aerosol duct sealing is commercially available through Aeroseal, Inc. in limited geographic areas.
The estimated cost for aerosol duct sealing is $300 to $1800 per home.
There is no ongoing cost associated with aerosol duct sealing. Rather, savings for a typical home's heating and cooling bills are estimated to be $300 per year.
Aerosol duct sealing is performed in conjunction with required building code methods of sealing air ducts, such as tape and mastic, to improve the airtightness of the ducts. Only an insignificant amount of adhesive particles is deposited on interior duct walls, and they have no harmful effect on the indoor air quality of a building.
Not Applicable
The initial step in aerosol sealing is to temporarily seal all supply and return registers with tape, as well as junctions between register boots and wall or floor surfaces. The air handler also is sealed to prevent the adhesive particles from depositing on the heat exchangers. A large plastic tube is then attached to connect the blower to the duct system at the return or supply plenum. Before aerosol sealing, the ducts are tested to determine the leakage volume. The ducts are then pressurized and aerosol is dispersed by the blower until the sealing is complete (about an hour in most homes). Aerosol sealing is not recommended for gaps larger than 1/4-inch.
Aeroseal offers a 10-year warranty.
The most important benefit to aerosol sealing is cost savings. Lawrence Berkeley National Laboratory testing has demonstrated that aerosol sealing can reduce leakage by a factor of five to eight, saving an estimated $300 per year on the heating and cooling costs of a typical home. Aerosol duct sealing is also easy to use compared with traditional methods, such as applying mastic, because it eliminates the need to open wall, floor, and ceiling cavities to access hard-to-reach leaks. Additionally, occupant comfort is improved because proper duct sealing ensures that conditioned air is distributed where it is intended--in rooms, not in unconditioned areas and floor and wall space. The estimated cost for aerosol duct sealing is $300 to $1800 per home. The technology’s developer believes that it may take only one to three years to recoup the initial cost. Aerosol sealing is permanent, and accelerated aging tests show it does not degrade over time. | 
