Design Options For HVAC Distribution System

A. Bhatia, B.E.

Course Outline

Successful HVAC systems are the key to successful buildings. In a central system, air can be conditioned in a remote location in the air-handling units and distributed to the various rooms by ductwork. Or the air can be conditioned directly in the indoor spaces through fan coil units or other terminal devices.

The design of air distribution system must combine a proper choice of engineered products efficiently providing conditioned air to the space while adding architectural features which complement the interior design. A good understanding of the various types of commercial HVAC systems is important to ensure the best fit.

This 4-hour course provides basic knowledge about the HVAC distribution systems in design applications. The course provides insight to various systems, technologies and equipment configuration with advantages and disadvantages. The course is intended for use primarily to the students, end users, operators, energy & environmental auditors, contractors, O&M engineers and sales people.

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:

• Be able to recognize the various HVAC distribution options;
• Be knowledgeable about the various system configurations; and
• Be able to conceptualize, judge and select the right system.
  

Course Introduction

Primary objective of HVAC system design is to realize the end objectives of (a) meeting indoor temperature & humidity requirements (b) indoor air quality (c) air movement (d) cost effectiveness (e) energy conservation (f) fire safety, (g) design flexibility providing ample scope for expansion / modifications and (h) ease of maintenance.

Air conditioning systems can be categorized according to the means by which the controllable cooling is accomplished in the conditioned space. They are further segregated to accomplish specific purposes by special equipment arrangement.

The course provides description for four basic system categories:

Section 1 Central Air conditioning Systems - All Air Systems

• Single Zone Systems
• Dual Duct Systems
• Multi Zone Systems
• Reheat Systems

Section 2 Constant Volume and Variable Volume Systems

• Constant Volume Systems
• Variable Volume Systems

Section 3 Central Air conditioning Systems - Air and Water Systems

Section 4 Central Air conditioning System - All Water Systems

• Two Pipe Systems
• Three Pipe Systems
• Four Pipe Systems
• Section 5 Terminal Units
• Fan Coil Units
• Induction Units
• Radiators

Section 6 Compact Unitary Units (direct expansion Systems w/o chilled water)

• Window Air conditioners
• Unitary & Roof Air Conditioners
• Split type and package air conditioning systems
• Heat pumps
• Delivery items (diffusers, registers & grilles)
  

Course Content

The the course content is in a PDF file Design Options For HVAC Distribution System. You need to open or download this document to study this course.

Course Summary

Proper selection of air-conditioning system is essential to achieve desired performance within economical limits. This includes primary influence from the architect and consideration of both the cost and design aspects during selection of system by the HVAC design engineer.

The HVAC equipment configuration and variants available in the market today provides enough options. If conditioning is transferred only by means of heated or cooled air, the system is termed an all-air system. If conditioning is transferred only by means of hot or chilled water, the system is termed an all-water system. If conditioning is transferred by a combination of heated/cooled air and hot/chilled water, then the system is termed an air-water system.

Further the systems are classified as single zone, multi-zone, reheat, constant volume or variable volume systems.

In a constant volume system the volume of air is held constant while the temperature is varied to meet the changing load conditions.

In a VAV system, the volume of constant temperature air modulates to meet the changing load conditions. The popularity of VAV systems has grown rapidly due to their ability to save large amounts of heating, cooling and fan energy when compared to other HVAC systems.

The air-conditioning could be achieved through the central systems or the compact unitary systems, the choice of which is essentially governed by economy of scale and energy usage.
Central systems are intended to condition multiple spaces in a building that usually have distinctly different equipment elements for each function.

Compact systems generally serve only one space or zone of a building (local systems) often incorporate all functions in a single piece of equipment. Domestic window, split, package, rooftop, heat pump equipment are the examples.

A good understanding of the various types of commercial HVAC systems is essential for HVAC designer to meet the needs of fast track projects and at the same time ensure that the building gets the environmental system that will best fit its needs.



Related Reading

Auxiliary Components of Chiller Package

The chiller package comprising of refrigerant compressor is a heart of main cooling system. The other two main elements of chiller package are called an evaporator for cooling water and condenser for heat rejection. For air-cooling applications, the production of chilled water is not mandatory and the system could be designed for the direct expansion (DX) type where the air is cooled directly with refrigerant medium. Further the heat rejection through the condenser could be through the air-cooled or water-cooled configurations. These aspects have been discussed exclusively with illustrations, advantages and disadvantages in another course HVAC made easy - 'Selection tips for cooling systems'.

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.

Refrigerants

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 two-hour course HVAC made easy - 'Facts about Refrigerants' briefly explores the myth and realities about refrigerants.



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

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DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDHonline.com 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.

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