Selection Tips For Air-Conditioning Cooling Systems

A. Bhatia, B.E.

Course Outline

This two hour online course provides comprehensive information on the air-conditioning cooling systems. It details the type and characteristics of commonly used cooling systems with illustrations, advantages and disadvantages. The course is intended for use primarily to the students, end users, consultants, architects, contractors and HVAC designers. The course focuses on the practical aspects of selection and is a recommended guide for the beginners and experience people involved in conceptualizing new project.

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will:

Course Introduction

The main purpose of a cooling system is to provide space cooling for human comfort or process cooling.

The heating, ventilation and air-conditioning (HVAC) systems are installed in buildings to provide occupant comfort, health and safety. A cooling system is a part of a HVAC system that provides space cooling.

In specialized applications, a cooling system provides cooling to meet process requirements as with the data centers, computer rooms, bio-medical facilities, manufacturing units, pharmaceutical facilities, laboratories and industrial process units.

The course focuses on two main categories of cooling systems namely the direct expansion (DX) system and central chilled water system. The course is divided as follows:

Course Content

The the course content is in a PDF file (73 KB) Selection Tips For Air-Conditioning Cooling Systems. You need to open or download this document to study this course.

Course Summary

The HVAC system required for cooling has two functions to perform:

The cooling of air can be accomplished by direct expansion of refrigerant in cooling coils (DX system) or through chilled water passing through a cooling coil.

DX system are designed to condition a single space or a portion of space from a location within or adjacent to the space. Such a system is also known as local self-contained system. DX systems could be applied to small or medium sized building requiring approximately 100 TR or less of refrigeration. The standard window, package and split units are typical examples of DX systems.

Chilled water systems are designed to condition several spaces from one base location. Chilled water is produced in a refrigeration plant located at one central location and is pumped to multiple air handling units (AHU) cooling coils scattered all over the facility. Use of central chilled water system shall be considered when air-conditioning two or more adjacent buildings or when the refrigeration loads are greater than 100 TR.

Heat rejection by the refrigeration equipment is accomplished in condensing unit that can either be air-cooled or water-cooled.

Air-cooled condensers offer greater advantages over water-cooled condensers up to 200 TR. Above this the water cooled condensers are more economical on life cycle basis.

Related Reading

Glossary and Acronyms

The course HVAC made easy - 'Glossary and Acronyms of HVAC systems' is a compilation of most common HVAC terminology and is a recommended reading. The abbreviations and terms that may be unfamiliar to someone exploring HVAC systems for the first time have been carefully selected and presented in alphabetical order.

Chiller Package

The chiller package comprising of refrigerant compressor is a heart of main cooling system. The chiller is a single most expensive item of the air-conditioning system that influences the life cycle economics of the air-conditioning system. The chillers have been discussed exclusively in another course HVAC made easy - 'Selection tips for chiller compressors'. This 2-hour course summarizes briefly merits and demerits of using different compressors.


The refrigerants are considered to be one of the major sources of Ozone layer depletion. The choice of refrigerant is interwoven with major environmental concerns of climate change and global warming. Refrigerant selection thus assumes a key importance in selection of HVAC system. A one-hour course HVAC made easy - 'Facts about Refrigerants' briefly explores the myth and realities about refrigerants.

Air-conditioning Sub-systems

The HVAC sub-systems play a key role in providing the controlled environment indoor particularly for multi-zone applications. Introducing reheat (energy inefficient) or use of variable volume control terminal boxes can achieve variable conditions in multi-zone applications. The various types of sub-systems, that provide heating and cooling to the occupied space via distribution of the conditioned air include:

These sub-systems have a little influence on the selection of main system and assume significant importance while detailing. These have been discussed separately in another HVAC made easy series.

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of 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 professional engineer. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.