This book is designed to provide the reader with a comprehensive overview of the heat pump system, its operations and principles. It should be noted that the heat pumps covered in this book are basic systems. The intent of the book is to offer technicians information to build upon, in order to enhance their knowledge of the air conditioning and heating field, and more specifically, heat pumps. Before installing or service a heat pump system, the technician must have proper training and knowledge of air conditioning/refrigeration theory, principles and operation. With today's energy demands and costs soaring there is a tremendous need for highly efficient equipment, and trained technicians that can install, service and maintain this equipment. New heat pump systems using HFC refrigerant (R-410A) are being sold and installed. These systems pose new demands for installers and service technicians. A heat pump's efficiency can be greatly diminished, regardless of the type of refrigerant, if it is not properly installed, serviced and maintained. This book covers problems and provides solutions to refrigerant charging, indoor airflow calculation, and methods of preventing unnecessary heat pump malfunctions.