ix Illustrations Illustrations have been designed to clearly and simply communicate the specific topic. Illustrations of hydronic heating systems and photographic images are provided to support learn- ing and comprehension for students to successfully enter the field. End-of-Chapter Content End-of-chapter material provides an opportunity for review and applica- tion of concepts. A concise Summary provides an additional review tool and reinforces key learning objectives. This helps you focus on important concepts presented in the text. Know and Understand questions enable you to demonstrate knowledge, identification, and comprehension of chapter material. Apply and Analyze questions extend learning and help you analyze and apply knowledge. Critical Thinking questions develop higher-order thinking and problem solving, personal, and workplace skills. Expanding Your Learning Career Connections explore the professional HVACR field and help you understand what you can expect in the workplace. Troubleshooting tips help you develop critical thinking, diagnostic and troubleshooting skills needed in the workplace today.