Commercial HVAC

A. Bhatia, B.E.

Course Outline

Commercial heating ventilation and air-conditioning systems may contain a myriad of components, many of which are present in one form or other in variety of configurations. Also these components may be assembled into systems literally dozen or hundred different ways, the boundaries between these system types are not absolute, and the choice largely depends on cost, aesthetics and degree of control. This 8-hour course provides the common system arrangements of commercial air-conditioning systems and discusses the most prevalent system configurations, equipments and control strategies.

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 reader will understand:

1. The components that make up a commercial HVAC system;
2. Centralized (DX v/s chilled water system) and Decentralized (unitary v/s split systems);
3.  “All- Air” ,  “Hydronic” systems and hybrid systems;
4. Constant volume, variable volume and dual duct systems;
5. Two pipe, three pipe and four pipe hydronic systems;
6. Variable refrigerant volume systems;
7. Air to air and water source heat pumps;
8. Chillers (reciprocating, screw, scroll and centrifugal) and their selection rating and energy efficiency opportunities;
9. Cooling tower terms, applications and types;
10. Different boiler types and efficiency terms used in heating systems;
11. Single zone, multi-zone, dual duct, variable volume and reheat air handling units;
12. Steam / hot water heating coils and DX /chilled water cooling coils;
13. Refrigerant and desiccant based dehumidifiers;
14. Centrifugal fans (forward curved, backward curved, radial) and axial fans (propeller, tube axial and vane axial);
15. Volume control dampers, backdraft dampers, fire dampers and smoke dampers;
16. Dry media filters, HEPA filters, activated carbon and electrostatic filters;
17. Air cooled v/s shell and tube condensers;
18. Hydronic pumps, valves and piping components;
19. Heat recovery devices such as run-around coil, plate & frame heat exchanger, thermal wheels and heat pipes;
20. Elements of control systems and control system equipment – control valves, dampers and actuators, I/O points, transmitters, relays and time clocks;
21. Single loop digital controller and controller action (direct action v/s reverse action);
22. Two position, modulating, open and closed control loops;
23. Proportional, proportional-integral (PI), proportional-integral-derivative (PID) control modes; and
24. Stability of control system and energy efficiency opportunities.
    

Intended Audience

This course is applicable to architects, mechanical engineers, HVAC designers, building contractors, H & S professionals and others in the design and renovation of commercial HVAC systems.

Benefit to Attendees

Attendee of this course will learn the HVAC requirements deemed necessary for right selection of system, equipments and control strategies and apply this knowledge in the design and renovation of commercial HVAC systems.

Course Introduction

HVAC stands for "heating, ventilation and air conditioning," three functions often combined into one system in today's modern homes and buildings. First and foremost, the objective of HVAC system is to create an optimal working environment.

Commercial air conditioning includes more than just the air conditioning unit itself. A complete system also includes the air distribution system (ductwork, dampers, grilles and registers), hydronic/refrigerant piping and the temperature and schedule control system. Each of these components makes an important contribution to the performance and efficiency of the system as a whole. In order to operate efficiently, a system needs to be properly sized and installed. Oversized units cost more to operate and do a poor job of comfort control, and poor installation can dramatically reduce the as installed efficiency of the system. The controls are also an integral part of the system and should include programmable thermostats and timers for scheduling of air conditioning equipment or a computerized energy management systems (EMS).

HVAC systems are also one of the biggest energy consumers. Choosing the right HVAC system, equipment and control strategy can mean greater comfort, lower first and recurring operational costs, easy maintenance, improve productivity and help meeting important sustainability initiatives over the life cycle of the system.

The course discusses the above criteria in detail and is divided in 3 modules:

Section -1 HVAC Systems

Section -2 HVAC System Components

Section -3 HVAC Control System Equipment and Control Loops

 

Course Content

This course is in the following PDF document:

Commercial HVAC

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.

Course Summary

HVAC systems and individual appliances come in many types and applications.

• A split system is a combination of an indoor air handling unit and an outdoor condensing unit. Split-systems are typically found in residential or small commercial buildings. • A packaged system is a single unit combining all the components described in the split system. Since the unit is a package, it must be placed outside the building and indoor air is “ducted” from the building to the packaged system and back through an air distribution system.

• Heat pumps are similar to cooling only systems with one exception that it contains a special valve to allow the refrigeration cycle to be operated in reverse. A heat pump can also cool the indoor air, but when the valve is reversed, the indoor air is heated.

• The window air conditioner is intended to cool small areas and is essentially a local system. It is not intended to provide cooling to multiple rooms or zones.

• In a chilled water system, liquid water is pumped throughout the building to “chilled water coils”. Since the liquid water needs to be at a cold temperature, a “cooling plant” is required. The plant is typically referred to as a chiller plant.

HVAC systems are classified as either central or de-centralized (local systems). Most centralized systems rely on some sort of heating system such as boilers, furnaces or electric heat; a cooling system such as air conditioning or chillers; and ventilation components. The main chiller, boiler or furnace is located in central place within the structure and the heating or cooling is achieved via hot water or chilled water circulated through a heat exchanger. The heated or cool air is than distributed through the ductwork. The centralized HVAC systems can be further classified into three broad categories: all-air, all-water, and air-processed in a central air-handling apparatus. Central plant design offers the HVAC engineer (as well as plant management) unique opportunities to find creative ways to conserve energy.

Control systems start and stop the HVAC system equipment according to a time schedule, and at specific outside air temperatures and specific indoor temperatures. Modern building energy management systems, EMS, provide immense potential to capture large amounts of time series data. But as a word of caution, never try to load your control system too much. Remember, when it comes to control, it may be better to have a building that is dumb and reliable than a building that is smart but scatterbrained. A simple strategy to minimize risk in this respect is to keep the controls simple and robust rather than complex.

Quiz

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 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.

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