Aerosealing the Deal

Inside view of the Aeroseal duct-sealing equipment as it’s heating, atomizing and mixing air, then sending the finished product toward the duct for sealing. Sensor tubes continually read internal duct pressures and send the data back to the computer to be calculated and shown.

Another obvious advantage is that the vinyl acetate polymer used in the process will find all the holes — not just the ones that can be seen. “It’s going to be very hard for a chief to find all of the gaps, St. Pierre offers. “This process does not require that a human being get to every hole.”

Not only will it find the unseen holes, but it will seal holes of pretty great size. “It’ll seal a hole up to 5/8 of an inch across, which still amazes me,” St. Pierre says. “And that’s the short dimension, Muller adds. “I mean, it could be four inches long by half an inch, and it would seal that.”

The cost of having the Aeroseal process executed on a property is, of course, wildly variable based on the size and extent of the job, among numerous other factors, but the residual benefits can be unexpected, as St. Pierre recalls of one particular job he handled some years ago. “It was a nine-story condo building, where there were 23 exhaust shafts in the building,” he says. “They wanted to seal the shafts for energy savings, and when I was on my initial valuation, we would walk down the hallways — the common hallways. And the common hallways were under a negative pressure. So basically, what was happening is, the building was under such a reverse pressurization that the hallways were pulling the odors from the condos out, so you could smell what everybody would be cooking.

“Obviously, in the correct world, the make-up air system should pressurize the main hallways, and then the air should go under the doors, and then the exhaust shafts should pull the air out of the bath and kitchens, out to the roof,” he continues. “Well, bottom line is, we sealed all 23 exhaust shafts in the nine-story building for energy purposes, the system was rebalanced [and] guess what went away? The pressurization issues went away. Now the hallways on all floors were now under a positive pressure, and all of the air was now going under the doorjambs into the condo units, and everything was working as it was designed to work, which, that building, from day one, I am sure was never under the proper pressurization. So we came in for one reason — to fix energy concerns, so they got these energy savings — and we actually ended up fixing another one while doing it.”

Outside view of the injection tubing leaving the heated tent and connecting to the temporary RTU injection collar. RTUs were being changed out and the sealing event was completed during that process. The tent is only needed when the outside temp gets low and adverse weather is expected.

A software program runs the Aeroseal system, with a digital pressure-reading system measuring the pressure as the process is underway. “I have pressure lines in the system that’s measuring pressure in the beginning as opposed to pressure at the end, or at different places,” St. Pierre says. “The software program is computing it live. I’m watching the actual leakage live on the computer as I’m doing the actual seal, so I know where I’m at. I do a pre-test in the beginning, as I’m sealing it, I’m watching it live in what we call a seal event — and as I’m sealing it down, I’m watching the actual leakage melt away, if you want to call it that. Then we do a post-seal test at the end, and then we provide a duct pressurization report, or, what we call a certificate of completion for that particular project.”

The ability to measure the variance in pressure from the beginning of the sealing event to its end is key. “When the process is over, we are able to document quite accurately what the reduction was in CFMs,” Muller explains. “How many cubic feet per minute less leakage as there was before — that we can quantify precisely, and I think you would find that a lot of chiefs, in their own head, have their own math about what that’s worth.”