Chapter 11 - Controls

Abstract

This chapter describes the basics of control and several control types, such as self-powered controls, electric controls, pneumatic controls, electronic controls (analog electronic), and direct digital controls. Well-designed controls are a critical part of any heating, ventilating, and air conditioning (HVAC) system, whether the controls are a factory package or built-up on site. The controls for a system may differ from project to project for a number of reasons. Design considerations for controls choices include availability of expertise in maintenance and operations of the controls, repair and maintenance expense budgets, and capital costs of control equipment. The chapter also discusses the physical structure and software of direct digital control (DDC) systems in detail, and some of the control possibilities that are available with DDC. The architecture of DDC systems and their advantages are also presented in the chapter.