Intermission (condensed from Practical Controls)

Okay, let’s take a breather here, and think about what we have talked about
thus far, before we go any further. It is important at this point that an
understanding of what has been covered has been established, and a
familiarity with the various terms and terminologies has been achieved. The
subsequent chapters will make reference to many of these terms without going
into any great detail as to the concepts behind them. In other words, these next
chapters “assume” that the reader has read and understands the content
making up the previous chapters. Okay, so what have we covered?

Chapter 1 provided an introduction to mechanical systems and controls, and
defined an HVAC system as a mechanical system plus the associated
controls and control system required to operate it. To that end, the chapter
attempted to define, in simple and concise terms and concepts, what a
mechanical system is, and what is meant to control such a system.

Chapter 2 gave an overview of mechanical systems and of the various
equipment making up these systems. The systems and equipment were
broken into three categories. Airside Systems and Equipment covered those
of which primarily deal with the movement of air, and the conditioning of it.
Waterside Systems and Equipment covered those of which mainly deal with
the movement and conditioning of water in HVAC applications. And
Miscellaneous Systems and Equipment dealt with those types that were
categorized as neither airside nor waterside. Hence a separate category for
these systems and equipment.

Chapter 3 formally introduced us to controls, by providing the fundamentals of
the various control methods in use today. Each section of this chapter, to an
extent, built upon the previous section. Two-position control was discussed
first, and then staged control. After that, we moved into proportional and
floating control methods. This chapter laid the groundwork for the following
chapters on actual control components.

Chapters 4 and 5 covered the “hardware” that is used to implement control
schemes and build control systems. Chapter 4 discussed sensors and
controllers, and took on a similar format as the previous chapter, at least in
terms of defining and categorizing controller types. Chapter 5 discussed the
various end devices that these controllers ultimately take control of. These two
chapters round out the whole topic of controls; by now the reader should have a
pretty good base knowledge of the topic, and thus should be well prepared to
take on the subsequent chapters on mechanical systems, equipment, and

Chapter 6 covered some common control schemes that are used with popular
mechanical systems. Each scheme of control was defined, so that we need
only refer to its defining term when we discuss these schemes in subsequent

You with me so far? Alright! Now let’s take a quick look at where we’re going!
The rest of this book will follow the format outlined in Chapter 2; each of the
following chapters will cover the mechanical systems and equipment originally
defined back in that chapter, in the precise order that they were listed there.
The first few chapters will deal with the airside, and will cover air handling
systems and zoning equipment. The following chapters will handle the
waterside, thus covering pumps, boilers, and chillers. The remaining chapters
will tackle that “miscellaneous” category.

It is important to note that all discussions up to this point have been necessary,
in order to comprehend the material in the upcoming chapters. A
“prerequisite”, if you will, to the rest of the book. It is these chapters to come
that are the prime reason for writing this book, yet in order to understand the
content, there needed to have been some groundwork laid. Furthermore,
understand that the upcoming chapters are not necessarily meant to provide
acute insight into the design concepts behind mechanical systems. Nor are
they meant to provide any great amount of detail into the mechanical “inner-
workings” of packaged equipment. These chapters are meant to provide a
solid understanding of how these systems and equipment should operate, and
how they can be controlled to meet that end, with methods that are “practical”
and controls that are “available”.

Okay. Intermission is over. Time to grab your popcorn and your soft drink and
“get back to the show”!

Practical Controls Book Excerpts