Famous mathematician Edward Lorenz coined the phrase “The Butterfly Effect,” which is the belief that some small occurrence could create devastating results in another location far away. It theorizes a hurricane could be caused by the flapping of a butterfly’s wings days or weeks earlier thousands of miles away. This theory always made me think of low-pressure steam systems. A small change or adjustment in one part of the system can affect other parts of the steam system. For example, a local school district had a classroom that would not heat. By the time I arrived, they had replaced the steam trap twice and the control valve once. We found the cause and solution to the problem three stories below, in a crawlspace. The asbestos abatement company removed the pipe hanger on the condensate pipe in the crawlspace and never reconnected it. The abatement crew crawled over the pipe, causing it to sag, which created a water seal. This affected the breathing of the system. Once the pipe was raised and the hanger reattached, the room heated normally.