Aeroseal Frequently Asked Questions


Aspen Air Duct Cleaning is an approved Aeroseal Dealer, licensed and ensured, and a member of the National Air Duct Cleaners Association (NADCA) and National Organization of Remediators and Mold Inspectors (NORMI). Following are some of our most frequently asked questions.

Aeroseal Frequently Asked Questions

Why should ducts in commercial buildings be sealed?  How much energy does the sealing process save?  How does Aeroseal work?  These are the questions we hear a lot and you’ll find the answers below.  If you have any other questions please do not hesitate to contact us – we’re here to help!

Why should ducts in commercial buildings be sealed?
Duct sealing in commercial buildings cost-effectively saves energy, improves air balance and thermal distribution (comfort and ventilation), and helps comply with building codes and specification for air distribution effectiveness.

How much energy does the sealing process save?
Energy savings are different for each building and HVAC system and obviously depend upon the initial air duct tightness. The Aeroseal Energy Savings Excel spreadsheet can be used to estimate the savings for most types of buildings.

In smaller commercial buildings with air ducts outside the insulation barrier of the building, energy savings can be as much as 30% of HVAC energy use. In large buildings Aeroseal duct sealing can reduce fan-system energy use by as much as 40% and reduce heating and cooling costs by as much as 10%.

As a rough estimate, simple paybacks typically range from 3 to 7 years. In some cases building owners have recovered the investment in Aeroseal duct sealing in less than 18 months.

Is the sealant used in Aeroseal safe?
The sealant material has been certified to UL1381, the industry standard for aerosol duct sealants. It is tested to rigorous requirements for flammability, smoke inhibition, mold growth and durability. The sealant has no OSHA Exposure Limit and no special precautions are required during application. It cures in less than two hours and meets LEED requirements for low VOC emissions.

The dried sealant material is primarily vinyl acetate polymer (VAP), which has been used in chewing gums, latex paints and hair sprays.

How long will the seals last?
The sealant has a life of over 30 years. Scientists at Lawrence Berkeley National Laboratory tested the performance of Aeroseal seals for 4 years under accelerated conditions, and were never able to observe a failure. This corresponds to 100,000 cycles under more severe temperatures and pressures than are found in duct systems.

How do I know if the ducts in my building need to be sealed?
The duct leaks can be uncovered several ways. Aeroseal has developed a simple survey (link) that can accurately predict if an air distribution system is leaking excessively. Another method is to review a Test and Balance Report and compare the flow at the HVAC system supply or return fans and sum of the flows measures at the supply diffusers or return grilles. Testing a sample of duct sections for leakage is an accurate way to identify if ducts are too leaky. Aeroseal technicians regularly perform this test.

How does the Aeroseal process work?
The Aeroseal process seals duct leaks from the inside, using small sealant particles that deposit at the leaks without coating the interior of the duct system.

This is accomplished by pressurizing the duct system with a fog of sealant particles sized to stay suspended in the air until they try to exit the duct system. By blocking all of the intentional openings in the duct system (i.e., diffusers or grilles), all of the sealant-laden air is forced out through to the leaks. As the duct pressure causes the particles to accelerate through the leaks, they stick to the edge and build upon each other until the leaks are sealed. By constantly monitoring the duct pressure and flow, the process-control computer calculates and the displays the remaining leakage in real time. When the sealing is finished, a complete minute-by-minute record of the process is printed, stored on the local computer, and then uploaded over the internet for archival on the Aeroseal server.

How large of a leak can be sealed?
Aeroseal recommends sealing the leaks up to 5/8 inches across. Leaks more than one inch across can be sealed, however the sealing rate varies with the size of the leak times itself. In other words, the sealing time for a 1″ leak is 64 times longer than that for a leak 1/8″ across.

Practically speaking, leaks larger than about 5/8″ across are better suited to be sealed manually if possible.

What types of ducts can be sealed?
Aeroseal is capable of sealing all types of ductwork. It has been successfully applied in rigid metal and flexible air ducts. It has been applied in duct with internal insulation. It has also been installed in duct systems fabricated of ductboard, drywall or masonry blocks.

Aeroseal avoids sealing through VAV boxes or fire/smoke dampers.

What about VAV boxes and fire/smoke dampers?
Aeroseal generally avoids blowing sealant materiel through VAV boxes or fire/smoke dampers, however laboratory and field testing have shown that under the right circumstances this can be done without adverse consequences.

Under no circumstances can sealant material be blown through VAV boxes with reheat coils. Should it be more practical to blow sealant through VAV boxes or fire/smoke dampers, it is recommended to consult with the engineers at Aeroseal LLC.

Do ducts need to be cleaned prior to sealing?
Extremely dirty ducts should be cleaned.  We recommend that the technician assess the condition of ducts prior to beginning to Aeroseal process.

Can I clean my ducts if they are sealed by Aeroseal?
Ducts of all material types can be successfully cleaned after they have been sealed with Aeroseal.

Can Aeroseal be used to seal air leaks in exhaust duct systems serving Type I (grease) commercial kitchen hoods?
We do not recommend Aeroseal to seal air leaks in exhaust ducts serving commercial kitchen grease & heat removal hoods (Type I hoods).  The sealant is not listed or rated for use as a duct sealant for these types of systems, and harsh cleaning chemicals used to clean the ducts could remove or degrade the performance of any seals.

Don’t see the answer to your question? Let’s talk!

Source: Aeroseal

Please contact Aspen Air Duct Cleaning at 1-800-931-6653 for an Air Duct System Inspection and to learn more about how sealing air duct leaks can improve indoor air quality and reduce energy costs. Or email

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