Is Aeroseal Worth It? Discussing The Pros and Cons of Aeroseal in 2020

As Aeroseal dealers, Green ID obviously uses and believes in the product.  We have performed dozens of Aeroseals on all types of homes.  One advantage we have is that our services also include energy audits and ductwork pressure testing, manually sealing the ductwork, Manual D duct design and sizing, installing new and modifying existing ductwork, and air balancing.  This exposes us to a wide range of comfort, efficiency and health and safety conditions related to the ducts and improves all aspects of our work but in particular, the Aeroseal process.  In similar way to how weight training will improve a swimmer’s time, performing energy audits lets us test the leakage at each register and use zonal pressure readings to find where major leaks are occurring before we even go in the attic.  Manually sealing the ductwork physically puts us in front of each duct so we can see mistakes and gain experience where we might need to put a set of eyes on common problems areas.  Ductwork sizing and design lets us know how to set realistic expectations for Aerosealing and know when to use it as a comfort solution, energy saving solution or efficiency improvement and know when another recommendation is better suited to solving a homeowner’s comfort, dust or efficiency problems.

What is Aerosealing?

Aeroseal is a method to seal the ductwork from the inside using a hot polymer glue.  The Aeroseal machine gets connected to one of the ducts with a clear plastic tubing while all the other registers are sealed off and isolated from the evaporator coil / heat exchanger.  Once connected, the Aeroseal machine uses a fan, heater and manometer to pressurize the ductwork and spray the aerosized glue through the ducts.  Its’ ingredients are those commonly found in pacifiers and chewing gum and are non-toxic.

The Benefits of Aeroseal Are:

DOE studies have shown the benefits of Aeroseal, you can read the report here and include.

1. Reduced dust
2. Improve air conditioning and heating performance
3. Improve home comfort
4. Lower energy bills

What Are Aeroseal’s Limitations?

This is Aeroseal’s standard benefit list but what it doesn’t tell us is how much each of these benefits will apply to your home.  In some cases, the there will be no noticeable dust change because the dust is coming from a dryer vent or air leak.  In other cases, Aeroseal really won’t improve your comfort because the sizing of the ductwork is main cause of comfort issues.  Some homes will see no improvement in their energy bills but their dust will be reduced noticeably.  The best way to find out how these interplay is to have a comprehensive energy audit on your home. 

Aeroseal’s biggest limitation is that it can only seal holes smaller than 5/8”, which is pretty small.  Leaks in the ductwork that are larger than 5/8” must be sealed manually first.  This can be a problem if your duct system has larger leaks because Aerosealing is more expensive than manually sealing the ductwork but won’t get to the heart of your duct leakage problem.  Another limitation is the actual Aeroseal company, especially if they are a larger solar or HVAC company, their Aeroseal crew likely won’t go in the attic to find the larger leaks.  I’ve come behind these companies to find that they did not go in the attic during the Aerosealing to manually seal the larger leaks and were either to lazy or not well trained to find the more important, larger leaks in the system.

What’s Better Aeroseal Or Manual Duct Sealing?

Companies that only perform Aeroseal would have you believe that Aeroseal gives a far superior seal on leaky ductwork but that’s not true.  The truth is that because Aeroseal seals the ducts from the inside, we don’t need access to the ductwork to seal it, so Aeroseal is better suited for those homes.  Examples of homes with inaccessible ducts are on a metal trunk system, 1st floor ductwork on a two story home, or on flat roofs.  On these homes, Aeroseal is preferred to solely manually sealing the ductwork, but a manual duct seal still needs to be done on these homes when feasible. 
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If the ductwork is fully accessible, then manually sealing the ductwork with mastic is more effective and less costly than Aerosealing.  Why is manually sealing the ductwork more effective than Aeroseal?  It’s because we can apply a much thicker layer with a more rigid backing on larger leaks than Aeroseal applies.  A thicker layer of mastic will obviously last longer than a thin layer and hold up again the ductwork expanding and contracting over time.  On most tract homes, the ductwork is 100% accessible and a manual duct sealing can be done with good results.

Under Pressure

Part of the Aeroseal process can be similar to running a blower door test on a home.  If you’ve had an energy audit done, you’ll be familiar with this test.  A blower door is a diagnostic tool our energy auditors use to put the home under pressure to measure and find air and ductwork leakage.  You can actually feel where the leaks are coming from when under a negative pressure around leaky doors, windows, duct registers, pocket doors, etc.  During an Aerosealing, we isolate the ductwork and put the duct system under a similar positive pressure test.  During this test we can again feel where the leaks are coming from in the ductwork, however we are able to put the ductwork under a much greater pressure where you can really hear, and feel where the leaks are coming from.  Once we take a crawl around the attic and check the HVAC system, I’ve been surprised to discover “hidden” leaks in the ductwork I would have never found from doing a manual seal alone.  As both Aeroseal and manual duct seal installers, we learn a lot going back and forth from manually sealing the ductwork to doing Aerosealing and here are some nuggets we’ve learned over the years.

How Aerosealing Has Made Me Better At Ductwork Sealing

1. Valuable Sealing Gold Is Inside The Unit.  Opening a furnace, air handler or package system is a must when Aerosealing ductwork to isolate the ducts from the evaporator coil.  While the Aeroseal machine is running, Green ID technicians are trained check the inside unit and ductwork for leaks.  One place we’ve found leaks is after we’ve taken the blower motor out where the motor housing sits.  These duct leaks come from the manufacturer when assembled.  They are important because duct leakage is not all the same, a leak closer to the unit is more important than the same size leak by the register, some 25 feet away.  A leak closer to the HVAC system is under a higher pressure than a leak 25 feet away, which is why if we only had 1 hour to seal the ductwork, we would start closest to the unit and work our way out to get the most costly leaks first.  This type of leakage we would have missed doing manual sealing because it is often out of sight.  Even when we have done a manually sealing of the ductwork and post tested the home (Aerosealing the ductwork has a build-in post test), that leakage was missed and accounted as unaccounted for loss.  After we starting sealing the inside of the unit, our leakage numbers consistently dropped.
2. Trunks Leak From Anywhere and Everywhere.  Before Aeroseal, we sealed metal trunk ductwork by hand.  This was a laborious process of unwrapping the trunk, finding the S cleats and Drives every 3 feet that connect the trunk and T’s and then sealing all three sides, with the fourth underside not accessible.  Sometimes I’d find if we didn’t clean the trunk ductwork well enough, the mastic sealant would stick to the dust and miss sealing the leaks.  Even then we are missing bottom side because it’s too close to the drywall.  With Aeroseal, we can hear and feel where these leaks are coming from, and it’s a useful diagnostic tool.  I’ve sealed trunk ductwork while the Aeroseal machine is running only to discover that I didn’t seal it well enough and the pressure created a new hole in my sealant.  Sometimes I can hear the hiss of a ductleak on the trunk in a random place that was put together poorly.  With the Aeroseal machine putting the ductwork at a high pressure, it’s easy to isolate those leaks and seal them by hand.
3. Elbows Leak The argument could be made that using the Aeroseal machine to help identify leaks can also be done with a blower door test by simply reversing the fan and pressurizing the home (or using a duct blaster for the same purpose), and it’s true.  When I was just starting out, that’s how I identified leaks in the home.   However, even with the blower door cranked up to it’s max speed, we could never build enough pressure to mimick the pressure the aeroseal machine does.  The higher pressure of the Aeroseal machine lets us hear and feel much clearer than with the a blower door.  A duct blaster isolates the ductwork but the tape commonly used to seal off each register would never hold once the pressure started to build in the ductwork, that’s why we use tight fitting Aeroseal plugs in the register boots so we can build a pressure of 400-700 PSI in the ductwork.  So while we have the ducts under pressure, I’ve been surprised to find a lot of leakage inside the elbows of package systems.  Yes, we normally this seal these duct leaks by hand around the elbow to roof jack, elbow to unit connections, divider plate, plenum to jack and flex to jack connections but without the Aeroseal machine running, I wouldn’t have realized how bad these can actually leak air.  I needed the Aeroseal machine to build a high enough pressure to actually hear and feel the leakage.

How Much Does Aerosealing Cost?

Aeroseal costs can vary between $1600 - $2300 per unit.  Manually sealing the ductwork costs can vary between $900 - $1200 per unit.  These costs can vary depending on the accessibility of the HVAC unit, the type of HVAC system, the number of registers in the home, the height and access to each register and how many systems are being sealed at one time. Visit Aeroseals website for more information on their product or contact Green ID to see if Aeroseal makes sense for your home.