Basics of HVAC (Heating, Ventilation, and Air Conditioning)
Jun 07, 2017

Overview of HVAC System

HVAC stands for Heating, Ventilation and Air Conditioning. HVAC is important in the design of medium to large industrial applications like power plants, onboard vessels, office buildings such as skyscrapers, and in marine environments such as aquariums, where safe and healthy building conditions are regulated with respect to fresh air, temperature and humidity.

Air conditioning ranges from simple air conditioning by use of packaged type window AC and single-split AC where cooling, minor filtration and dehumidifying, is done to much complicated air conditioning systems used in process plants, vessels, laboratories, and centrally air conditioned office buildings.

Need for HVAC

The objectives of HVAC  is to control the air condition  inside the designated space such as temperature, humidity,, air quality, supply of outside fresh air for control of oxygen and carbon dioxide levels, and finally, control of the movement of air or draught. Managing these factors equate to  a successful HVAC system. Air conditioning has changed over the years from just cooling of a space to the effective control of all the above parameters.

Modern HVAC began in Buffalo, New York, on July 17, 1902, in response to a quality problem experienced at the Sackett-Wilhelms Lithographing & Publishing Company of Brooklyn, Willis Carrier submitted drawings for what became recognized as the world's first modern air conditioning system.

Processes in HVAC

The processes by which effective control of parameters in an air conditioned space is maintained are as follows:

Heating: To increase the temperature by adding thermal energy to a space.

Cooling: To decrease the temperature by removing thermal energy from a space.

Humidifying:  To increase the relative humidity of a space by addition of water vapor or steam.

Dehumidifying: To remove the water vapor or humidity of a space.

Filtration: To remove dust, pollens, smoke and contaminants from air inside the space.

Ventilating: To allow external fresh air into the space to ensure  acceptable oxygen levels.

Air movement: To control the movement of the supplied air so that the inhabitants of the space do not feel discomfort.

Components of an HVAC System

There are two main components of a HVAC  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/boiler. In an air conditioning system, the cooling system is composed of a number of unique subcomponents varying for different HVAC systems.

Types of Air Conditioning Systems

Different types of air conditioning systems are recommended for different applications. The most commonly used are described henceforth.

The choice of which air conditioner system to use depends upon a number of factors including how large the area is to be cooled, the total heat generated inside the enclosed area, etc. all the related parameters are considered and the system most suitable for your space suggested.

  • Window Air Conditioner

Window air conditioner is the most commonly used air conditioner for single rooms. In this air conditioner, all the components, namely the compressor, condenser, expansion valve or coil, evaporator and cooling coil are enclosed in a single box. This unit is fitted in a slot made in the wall of the room, or more commonly a window sill.

  • Split Air Conditioner

The split air conditioner comprises of two parts: the outdoor unit and the indoor unit. The outdoor unit, fitted outside the conditioned room, houses components like the compressor, condenser and expansion valve. The indoor unit comprises the evaporator or cooling coil and the cooling fan. For unit you do not require any slot in the wall of the room. Further, present day split units have aesthetic appeal and do not take up as much space as a window unit. A split air conditioner can be used to cool one or two rooms (Multi Split).

  • Packaged Air Conditioner

This type of air conditioner is suggested if one wants to cool more than two rooms or a larger space at your home or office.. In this arrangement, all the components, namely the compressor, condenser (which can be air cooled or water cooled), expansion valve and evaporator are housed in a single box. The cooled air is thrown by the high capacity blower, and it flows through the ducts laid through the large space or various rooms.

  • Central Air Conditioning System

Central air conditioning is used for cooling big buildings, apartment buildings, offices, entire hotels, gyms, movie theaters, factories etc. If the whole building is to be air conditioned, putting individual units in each of the rooms is very expensive making this a better option. A central air conditioning system is comprised of a high capacity condensing unit that has the capacity to produce hundreds of tons of cooling. Cooling big halls, malls, huge spaces, galleries etc is usually only feasible with central conditioning units.

HVAC industry and standards

The HVAC industry is a worldwide enterprise, with roles including operation and maintenance, system design and construction, equipment manufacturing and sales, and in education and research. The HVAC industry was historically regulated by the manufacturers of HVAC equipment, but regulating and standards organizations such as AHRI, ASHRAE, SMACNA, ACCA, Uniform Mechanical Code, International Mechanical Code, and AMCA have been established to support the industry and encourage high standards and achievement.

ISO 16813:2006 is one of the ISO building environment standards. It establishes the general principles of building environment design. It takes into account the need to provide a healthy indoor environment for the occupants as well as the need to protect the environment for future generations and promote collaboration among the various parties involved in building environmental design for sustainability. ISO16813 is applicable to new construction and the retrofit of existing buildings.