Using glycol in a heating system in Minnesota is essential to prevent freezing in colder temperatures. Eric shows how the glycol mixture is connected to a system using a digital mini feeder, which helps maintain pressure and proper flow throughout the closed-loop system. By using the glycol feeder, there is no need to connect to potable water, reducing the risk of cross-contamination. This self-contained unit ensures that the heating system operates efficiently and effectively, providing heat even in the event of power loss or system malfunctions. Overall, the glycol feeder is a critical component in ensuring the functionality and reliability of the hydronic heating system in the Duluth Build project.