Basic Principles of a HVAC system

A good knowledge of HVAC basics is essential when it comes to upgrading or installing ventilation systems. In this article, our aim is to help you understand these simple yet useful concepts.

What is HVAC?

HVAC is an acronym for ‘Heating, Ventilation and Air-conditioning’. It can also be thought of as a climate-control mechanism to ensure that humidity and temperature are properly regulated in a living environment. A basic knowledge of HVAC systems includes the principles of system operations, an understanding of the factors that determine the capacity of the equipment and also the various components that make up a HVAC system.

Basic Principles:

The following factors determine the capacity of HVAC system required:
  • Heating: The amount of thermal energy that needs to be added to the space.
  • Cooling: Thermal energy will sometimes need to be removed from a particular space in order to bring the temperature down.
  • Humidifying: This refers to the process of increasing the relative humidity through the addition of water vapor into the system.
  • Dehumidifying: Process of removing water vapor from the given space.
  • Cleaning: Purifying the air by the removal of dust, smoke, pollen and other pollutants.
  • Air Movement: Ensuring that there is ample movement of air to keep the inhabitants comfortable.
A chart known as the Psychometric chart is very useful in understanding how these different factors interact with each other. This chart is integral in performing the calculations that determine the type of system required.

Removal of Heat form an HVAC system:

There are many methods to remove heat form a building. It is a common misconception that air conditioners are the only option. A heat pump can also be used which offers many advantages to a traditional AC. The different types of ACs that can be used are direct expansion, chilled water, split and window.

Components of an HVAC system

There are three main components to any HVAC system. These are the air handler, heating & cooling system and the heat exchanger. A furnace of some sort is usually used as the basic heating component. The air conditioning system will be slightly more advanced with a number of smaller sub-components.
Heat exchangers come in a number of different types and models. The design depends on the application of the heat exchanger. The basic functioning is that of exchanging heat between two fluids without their mixing.

The role of refrigerants

The refrigerant gas is the most important part of an air conditioning system. Most ACs work on the principles of compression and expansion of the refrigerant. The gas becomes very hot when it is compressed. Then it is sprayed on to the walls of the heat exchanger. R-12 is the primary refrigerant used in air conditioning. Recently though it is being phased out in favor of the R-34a.
This is just a basic overview of the many different components of a HVAC system. As you can imagine, the subject goes into far more depth and detail. However this should be a good starting point for any aspiring engineer.




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