HVAC Design Principles and Major System Components
written by: Mike Aguilar
• edited by: Lamar Stonecypher
• updated: 10/14/2011
Whether you're upgrading an existing system or building a new one, good knowledge of the principles of heating and air conditioning, and typical designs, will allow you to make wise decisions when the time comes. These principles, along with descriptions of typical components, are referenced here.
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HVAC stands for Heating, Ventilation, and Air Conditioning. This is the building system that regulates the inside temperature of the building and, in some systems, the air quality as well. The principles of HVAC design include the basic theory of system operation and the factors that determine the size and capacity of the equipment installed in the system. Once you have an understanding of the basics, you’ll be given information concerning the different types of air conditioning systems. The next step is to learn about the various components that make up an HVAC system. For example, the air conditioning portion of an HVAC system requires refrigerant to cool the air inside the building, so the various refrigerants that can be found in air conditioning systems are fully discussed. Finally, you’ll learn about the details of HVAC system installation, including the placement of compressor and condenser units, as well as heat exchangers, zones, and controls.
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Basic Principles of HVAC System Design, Operation and Determining Capacity Requirements
Referenced here are informational resources regarding the basics of HVAC design and operation. When upgrading a current HVAC system or getting ready to build a new system in a residential or commercial building, one of the most important design considerations is correctly calculating the heating and cooling loads that the system will support. These calculations are described in complete detail in the articles below and sample calculations are given to help you achieve the fullest understanding of how to make the calculations properly possible. After reading through this section, you will have the knowledge and tools required to make good HAVC system design decisions.
Different Methods for Removing Heat in HVAC Systems
Air conditioners are not the only systems available in HVAC for the removal of heat from a building’s environment. A heat pump is similar to an air conditioning system, but has some significant differences, and advantages. These differences are discussed in detail so you will be able to make a decision between the two, and just so you have an understanding of what these two types of systems are. A nice variety of types of air conditioning systems can be used in overall HVAC system design. System types such as direct expansion, chilled water, split, and window air conditioners are described in detail in the resources referenced below. After reading through this section, you will have a more complete understanding of the different types of cooling systems available for HVAC systems.
There are two main components of a heating, ventilation, and air conditioning system. These two parts are the air handler, heating and cooling system, and the heat exchanger. In most cases, the heat source is some type of furnace. In an air conditioning system, the cooling system is composed of a number of unique subcomponents. In the articles referenced below, the various components in an HVAC system are described and explained. You’ll also find a description of the components in a split air conditioning system.
Most air conditioners operate on the principle of gas compression and expansion. This gas is known in the air conditioning and refrigeration industry as a refrigerant. When this refrigerant is compressed, it becomes quite cold. This refrigerant is then sprayed into the heat exchanger using some sort of expansion valve. There have been four main refrigerants used in air conditioners over the years. The refrigerant in primary use has been R-12, although this is being slowly phased out for R-34a. All of the different refrigerants are explained in detail, with special treatment for R-12, as the favored refrigerant for a number of years, being given.
An HVAC system with components that are incorrectly installed or installed in ways that are disadvantageous is one that is poorly designed. Maximizing airflow across the heat exchanger unit ensures maximum heat transfer and maximum system efficiency. A heating, ventilation, and air conditioning system that is improperly installed will also detract from system efficiency. Placing the thermostat too near an air outlet or return, for example, will also cause efficiency to suffer. How installation affects HVAC system design will be discussed below in some detail. Safety and longevity concerns are also briefly discussed.