For those not familiar with Aeroseal, it is a method of sealing your ductwork using adhesive particles blown into your ducts after they have been closed off and pressurized. It is akin to “fix-a-flat” for your ducts.
It is a patented process developed by researchers at Lawrence Berkeley and developed into a business called Aeroseal. Aeroseal was acquired by Carrier (the HVAC company) about a year ago.
The official website is here:
http://www.aeroseal.com/
After learning about Aeroseal after finding it through a link on the engerystary.gov website, I knew that was exactly what I was looking for. I planned on sealing the ductwork myself, but I could only seal what was reachable in the basement. The Aeroseal provided a much better solution as it seals the entire system, including the duct working the walls.
I scheduled a service date with the Aeroseal contractor and had them come out.
The first thing the contractors do is measure the loss of air in your duct work by pressurizing the system and hooking sensors up to a computerized pressure meter.
My pre-sealing stats:
Supply side ducts air loss: 246 CFM
Return air duct air loss: 1,161 CFM
To help visualize this, a typical mid-size refrigerator is roughly 25 cubic feet. So my supply side air ducts were loosing about ten refrigerators of heated air for every minute of run time! My return ducts were loosing about 46 refrigerators of air for every minute of run time!
The Aeroseal techs first worked on the supply side. They hooked up the machine that pressurizes the ducts and blow in the adhesive particles. As the particles find the leaks, the build up and eventually seal the hole. You can watch the computer monitor as it graphs the air loss in CFM over time and the graph continues to drop. The techs watch the monitor and once the graph flat lines there is no more ability to seal additional holes. You can never get the ducts to zero CFM loss because the pressurization and temperature required would be to great (the sealant is heated as it is blown in).
The biggest problem that I had was that the techs were not able to get my return side duct leakage down as significantly as they wanted to. Most modern construction houses use wall cavities between the studs as the return ducts, rather than actual metal ducts like the supply side. The result is that when plumbing and electrical wiring is run they drill large holes in the studs and cause leaks that are too large for the Aeroseal sealant to work. The techs did the best they could, but as you see in the results below, the reduction in the return air side was not as great as the supply side.
My after sealing stats:
Supply side: 83 CFM (a 68% improvement in leakage).
Return air: 760 CFM (a 35% improvement in leakage).
After the techs are done they print off a paper report showing you the before and after measures and a graph of the sealing done in minutes and how the CFM leaked was reduced.
Does it work? Well I have no quantified measures yet to say if it made a large dent in my heating/cooling costs. I certainly seems that the heat runs in significantly shorter cycles as much more heat makes it way to the living space rather than leaking out in the wall cavities. Our rooms are more evenly heated. Our master bedroom used to be at least 2-3 cooler than the rest of the house. Now is close to the same temperature. I always keep my house at a max of 68 degrees in the winter. My wife and I used to get very cold hands and feet, now In general the house feels “warmer” and more comfortable even at the same temperature.
Pros:
-Effectively seals all ducts inside and outside of your walls
-The Aeroseal techs also manually seal the ductwork they can reach in areas like basements/crawlspaces
-The energy star website says that duct sealing should save you between 10-20% in heating or AC costs
-The computerized report provides quantified evidence of reduction in air leakage.
-The service is also supposed to help reduce dust in the house and my wife is always complaining how bad the dust is in my house before the service was done. Did it reduce the dust? I don’t know, to early to tell.
Cons:
-Depending on where you live it can be expensive. Note that there is only one contractor in my state certified to perform Aeroseal service (Ohio). It was expensive because I had to pay for the additional drive time of two hours each way for the techs to come out. Aeroseal was originally founded in the Southwest, so there are more contractors out there and you should be able to get a better price. Also, some municipalities are offering rebates to encourage people to use the service. I’m an energy efficiency freak, so I felt the cost was worth it as a hedge for rising energy prices in the future.
-If you house uses wall stud cavities for return air, you probably will never get a good seal out of them unless you rip apart your walls and seal the areas by hand.
-If you have ducts that haven’t been cleaned in awhile, you will need to have a duct cleaning service first clean your ducts before Aeroseal can come in. Sealant doesn’t stick to dust very well (additional cost to factor in).
-If you’re a doomer, sealing your ducts won’t matter, because everything is collapsing anyways.
I'm checking those out now.