Essentials of Air Tightness Testing

Clock icon Created: July 1, 2020

As ATTMA certified blower door testers, training providers and official suppliers of TEC, we recommend the following essential tips to carry out the air tightness tests:

Do’s – Put the hose outside

When you’re setting up the blower door, run your hose to the outdoors before you completely assemble the door. If you don’t, you’ll either have to take it apart again, go through another door, or do the “crawl of shame” to get the hose in position (see Image #2, below). After you’ve suffered one or more of those inconveniences a few times, you’ll start remembering this every time.

Image Credit: Energy Conservatory

Do’s – Put the hose in a bag, can, or shoe

When you put the hose outdoors, you need to protect the end from wind. A good way to do that is to put the end of the hose in some kind of container that’s still connected to the outdoor air. You could use your shoe. You could use a plastic container. You could even use a bag. It just so happens that the little canvas bag for The Energy Conservatory’s DG-700 is perfect for this task.

In addition to protecting the end of the hose from wind, doing this also helps protect it from water. A drop of water in the end of your hose can mess up your results, too.

Do’s – Put newspaper over fireplace ashes

If you make the mistake of not checking the fireplace for ashes, the carpet is guaranteed to be white. I don’t know why this works, but I know from experience that it does. So, first, check the fireplace for ashes. One method I’ve found that keeps the ashes out of the house is to lay newspaper over the fireplace and then use a spray bottle filled with water to wet the newspaper. It works.

Do’s – Use Vent Caps

If you haven’t used Vent Caps yet, you’ll be amazed at the difference they can make in your setup time (see Image #3, below). They’re so much easier to use than grille mask, and if you do a fair amount of testing, they’ll pay for themselves pretty quickly with the money you save on grille mask. “Vent Caps changed my life.”

Don’t do the blower door test first

I used to go in and do the blower door test first, then set up and run the two duct leakage tests. If you’ve done any of this testing, you know that it takes much longer to set up for the duct leakage testing. If it’s a hot, humid, or cold day, when you run the blower door first, you’re making the house uncomfortable for the whole time you’re setting up the duct leakage tests.
Instead, do all your setup upfront. Then run your two duct leakage tests. Once you’ve got those results, unseal the vents and run your blower door test. Running the tests takes only a few minutes if you’re just measuring performance. If you’re doing a lot of diagnostic work, too, it’ll take a bit longer, but as soon as you’re done, you can get the air conditioner or heating system going again. Make sure your helpers know where to seal the vents.