Print this page Fundamentals of HVAC Controls
A. Bhatia, B.E.
Course Outline
The control system
in the Heating, Ventilating, and Air- Conditioning (HVAC) system can have a
significant impact on the building's comfort and energy consumption. The control
system manages the flow of heat, cooling, and ventilation throughout the building.
This 4-hour course covers the fundamentals of automatic controls in the HVAC
system. Emphasis is placed on the control principles, terminology, basic components,
control devices and direct digital control systems. Numerous illustrations and
examples have been included to enhance the understanding of the course material.
This course
includes a multiple-choice quiz at the end, which is designed to enhance the
understanding of the course materials.
At the conclusion of this course, the student should be able to:
- Define the basic blocks of control system;
- Distinguish between open loop and closed loop systems;
- Describe different types of temperature, humidity, pressure and flow sensors;
- Define setpoint, control point, offset and throttling range;
- Determine controller action for given the application;
- Distinguish between direct and reverse reset;
- Distinguish between the mixing and diverting valves;
- Define flow coefficient, valve authority, controllability, rangeability and turndown ratio;
- Describe the sizing of control valves;
- Define proportional control, PI control and PID control;
- Describe direct digital control terminology, hardware and control network; and
- Cite the energy
saving benefits of DDC systems.
This course is aimed at the personnel who have some limited background in the air conditioning field or who may be having difficulty relating controls to air-conditioning equipment. The course is suitable for students, mechanical, electrical, controls and HVAC engineers, architects, building designers, contractors, estimators, energy auditors and facility managers.
Course Introduction
In simplest term,
the control is defined as the starting, stopping or regulation of heating, ventilating,
and air conditioning system. The HVAC control systems can vary considerably
in size and complexity depending on the size and needs of the system. The conventional
HVAC control is maintained through individual controllers working independently
throughout the building. This is fine for simple buildings, but quite inadequate
for more complex buildings. As the building designs and HVAC systems became
more comprehensive, the controls also have become intelligent and complex.
This course describes the basic control fundamentals and briefly discusses the
digital controls. The complete design of microprocessor-based controls is not
the objective of this course, which requires in-depth knowledge of hardware's
of microcomputers.
Course Content
The course content is in a PDF file Fundamentals of HVAC Controls . You need to open or download this document to study this course.
Course Summary
The HVAC systems
are designed for peak conditions. Because these conditions prevail only for
small period in a year, the HVAC equipment must operate most of the time at
lean capacity. The function of the control system is to adjust the equipment
capacity to match the load. Automatic controls are necessary not only to achieve
the design conditions in the conditioned space but are also required for efficient
operation of the HVAC system. The main parameters to be controlled in air conditioning
system are temperature, pressure, humidity, air quality and thermal energy distribution.
Conventional controls use the electromechanical devices, which were OK for small
buildings but with greater emphasis being placed on the indoor air quality and
energy consumption, the trend today is shifting towards the digital controls.
The modern system rely on the microprocessor based controls, which besides providing
the normal control functions, monitors, records and communicate these parameters
effectively to centralized location.
It is important to note that the primary factor influencing the effectiveness
of HVAC system is the proper mechanical design itself. The HVAC system must
be properly designed to satisfy the process or comfort requirements. Only when
this criterion is satisfied can a suitable control system be applied.
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
