A few years ago, I had the opportunity to interview Gary Nelson, one of the founders of The Energy Conservatory (TEC) and Minneapolis Blower Door. During that conversation, he explained how his original hope for the blower door was that every contractor would own one and that testing both new and existing homes would become common practice. That was 40 years ago.

We aren’t there yet, but there are more contractors purchasing the tool because there are several good reasons to own a blower door. There are many online videos and webinars showing how a blower door is set up and used. Here, I will discuss how to perform basic diagnostics on a home using a blower door. I will include methods for finding air leaks, some talk on zonal pressure testing, and tasks a manometer can perform—all topics I think a contractor who owns (or wants to own) a blower door should know about.

Invest in the test

There are two major manufacturers of blower doors in North America: TEC’s Minneapolis Blower Door, and Retrotec. A third, Infiltec, also manufactures blower door equipment, but I have yet to see any of their products in the field. Both major manufacturers have on-demand online classes; for anyone who either owns a blower door already or is considering buying one, I recommend taking a class on how to correctly operate it. (Go to: Minneapolis Blower Door training and Retrotec training.)

There are also agencies that teach blower door testing alongside building science principles. For example, I am co-teaching the Building Analyst Technician (BA-T) training at Building Science Institute (BSI). It is a three-day course that covers a range of building science topics and includes lab instruction on blower door testing a home.

Locating air leaks

One of the advantages of…