This book is one in a series addressing building systems design,operation, and maintenance. The material presented in this book can be used for office reference, for formal in-house training programs, and for informal self study.The material is not intended to be used as a replacement for manufacturers’ instructions for specific equipment. This book is written to provide a complete and concise referencevolume for persons engaged in the operation and maintenance of automatic control systems serving building heating, ventilating, and air conditioning systems, including refrigerating machines, and interface to building automation systems (BAS) systems. Energy management and control system (EMCS) are of such diverse types and arrangements that it is not possible to cover them in this book.