When winter arrives in Korea, there is one feature of many Korean homes that you may quickly become aware of: the ondol, Korea’s traditional floor-heating system. Whether you have experienced it before or you are learning about it here for the first time, the ondol often feels noticeably different from the heating systems used in many other countries. As someone interested in how things work, I wanted to understand what may make the ondol unique—both culturally and mechanically. What I learned encouraged me to explore the system beneath the floor,…