How Can Sealing Your Ducts Save You Energy and Money?

   Properly sealing ductwork results in several benefits. It improves comfort by increasing the rate at which air is delivered to a space; it can prevent safety problems caused by carbon monoxide gas leaking from water and space-heating equipment; and it improves indoor air quality by reducing the infiltration of dust, humidity, and outdoor fumes and odors. It also saves energy. The most cost-effective time to seal ducts is when an HVAC system is first installed in new construction, because the ducts are easily accessed. However, ductwork can also be sealed in existing buildings. Duct sealing may be justified on the basis of its non-energy benefits alone, not to mention the benefit one can gain in energy savings. Research from Lawrence Berkeley National Laboratory shows that 10 to 20 percent of the air from an HVAC supply fan is wasted through leaks in entire HVAC duct system. Stopping this leakage could create significant dollar savings in certain climates.


Image Credit: Energy Star; A= Leaky connections; B= Leaky return; C= Furniture blocking registers D=Leaks at furnace and air filter slot and duct tape failures E=Fallen duct insulation; F=Leaku Supply Ducts G= Kinks restricting airflow.

What Are My Options?

Tapes and mastic. Metal-reinforced tapes and mastic approved by Underwriters Laboratories are the preferred, conventional choice for sealing ducts. Mastic is rubbery, fiber-reinforced goo that is applied with a brush. Large holes are generally patched with sheet metal and then sealed with mastic. Ducts are still often sealed with standard duct tape, but, despite its name, duct tape is a poor material for that purpose. The process of sealing your entire duct system using tapes and mastic is a very labor intensive process and not all areas of the home can be accessed limiting one's ability to effectively seal every single leak in the total HVAC system.

Aeroseal sealant. A technology sold under the trade name Aeroseal by Carrier Corp. has the potential to dramatically mitigate leaks and the problems they cause. It works by blowing sticky particles into ducts. The particles attach themselves to the edges of leaks and effectively seal them. The Aeroseal service includes diagnostics, repair, safety testing, sealing, and reporting, Aeroseal is the only technology on the market that can seal leaks in ducts made inaccessible by walls and insulation.

How Does the Aeroseal Technology Work?

   When the computerized Aeroseal process begins, all supply registers are removed and foam plugs are installed in their place. The Aeroseal machine is temporarily attached to the return-air plenum and the air-conditioning coil, fan, and furnace are all temporarily blocked with a foam plug so that sealant particles produced by the machine will not find their way into the equipment. The Aeroseal injection machine is then connected to the duct system using a long, flexible plastic tube.



   The Aeroseal software allows the technician to accurately measure duct system leakage. A fan blows small, dry adhesive particles into the temporarily blocked duct system, depositing these particles directly onto the edges of holes to create seals. Because all primary registers and the furnace are blocked, the suspended adhesive particles forced into the ducts have only one place to go. As the airstream exits the duct through leaks, the adhesive particles stick to the edge of the leak and build a seal up to five-eighths of an inch wide without leaving excess deposits on interior duct surfaces. The Aeroseal software allows the technician and the customer to view the sealing process in real time. In addition, while the sealing process is under way, the technician will manually seal leaks found at register boots (the connections from the duct to the register), at return platforms, and in HVAC equipment. Once the aerosol sealing is complete, the technician measures the duct system leakage using the Aeroseal machine. The computer measures duct leakage amounts before and after sealing and shows the improvement in overall system capacity.

   To learn more about how the Zero Energy Team in Phoenix Arizona can help you seal all the ducts in your home please contact us for a free estimate.