The first edition of this book provided fundamentals of HVAC control to practitioners who were designing new control systems or maintaining existing control systems. Emphasis on fundamental control system principles along with the psychrometrics of air conditioning processes has remained a focus of this new 2006 edition; however, readers will find that the fundamentals of existing control systems remain in this book so that those who need to maintain or troubleshoot systems that are 20 or 30 years old will be able to see what practitioners did during that time frame. The ubiquitous application of digital control technology in very recent times is also described. Also included is a new emphasis on controlling minimum fresh air for validation purposes. New techniques for doing this have been developed in response to ASHRAE Standard 62.1-2004, and these methods are included.

This edition covers both hardware control systems and modern control technology. Readers will be reminded of the psychrometric processes associated with heating and air conditioning as they learn of the various controls schemes used in the variety of heating and air conditioning system types they will encounter in the field. Descriptions of various control hardware and control strategies that were used in the past and are prevalent in most existing heating and air conditioning systems are included.