Although dimensional analysis is a fundamental skill in physics, very few studies examine how instructors teach it or how they expect their students to do it. In this phenomenographic study, we interviewed eight faculty from Oregon State University with diverse teaching and research backgrounds to better understand how they think about using and teaching dimensional analysis. The faculty identified the term "dimensional analysis" as referring to two different processes - using dimensions to derive equations or using units/dimensions to check for errors. The latter process is also referred to as "unit checking". The faculty expect students at all levels to be able to check units/dimensions. The faculty primarily demonstrate dimensional analysis to students but they do not explicitly teach how to perform dimensional analysis (for generating or checking equations) or require students to practice dimensional analysis in course assignments.