What Is An HVAC System

An HVAC system provides thermal comfort with indoor air quality; its initials stand for Heating, Ventilation, and Air Conditioning. An HVAC’s equipment includes heating equipment, ventilation equipment, and cooling or air-conditioning equipment. Their convenience makes them suitable for use in industrial, commercial, residential, and institutional buildings.

HVAC systems can be classified according to the heating, the cooling, and ventilation processes. Their distribution system varies according to the refrigerant type and the delivery method, such as air handling equipment, fan coils, air ducts, and water pipes.

Components of an HVAC System

The essential elements of an HVAC system are:

  • Mixed-air plenum and outdoor air control
  • Air filter
  • Supply fan
  • Exhaust or relief fans and an air outlet
  • Outdoor air intake
  • Ducts
  • Terminal devices
  • Return air system
  • Heating and cooling coils
  • Self-contained heating or cooling unit
  • Cooling tower
  • Boiler
  • Control
  • Water chiller
  • Humidification and dehumidification equipment

Functions of an HVAC System

An HVAC system controls the environment in which it works. It regulates the temperature of a room through heating and cooling. It also controls the humidity level in that environment by varying the movement and distribution of air inside the room. The system also ensures the cleanliness of the air.

Types of HVAC Systems

Split and Window AC Systems

In a window AC, fans blow air through the coils, separating the heat and cold. Heat gets lost to the outside air while introducing cold is into the room.

While window AC serves single rooms, Split ACs regulate air in larger. The split AC focuses on splitting the cold from the hot side of the system. The cold coil and the expansion valve are located on the air handler. The handler blows air over it and the cooled air is distributed to various rooms in the building through the air ducts.

Packaged Heating & Air Conditioning System

These units have both heating and cooling equipment in a single “package.” Users can place them in mechanical rooms, on the rooftop, or at a grade close to the conditioning space.

Unlike in split systems where the cold and hot units are separate, the package AC has all the components in one unit. These elements have a centrifugal fan or blower that helps distribute the air throughout the different ambients of the building.

Central AC Systems

Most of the air conditioners in residential buildings are split systems. They have the same operation as the Split System, only on a larger scale.  The compressor uses electricity as its source of power to pump the refrigerant across the system collecting indoor heat and removing it from the indoors. The heat dissipates outdoors by the coil in the condensing unit.

Warm air indoors gets blown through the indoor coil (cold) to remove moisture and heat. The heat in the air transfers to the coil, and thus the air cools. The water vapor condenses and collects inside a drain pan. It goes outside through the condensate drain.

The HVAC regulates the indoor temperature pumping the heat outdoors after flowing through the evaporator coil while the now cooled air inside the room circulates through the fan on the air handler.

Factors to Consider when Selecting an HVAC System

    • The age and size of your home or office.
    • The number of ambients to heat or air-condition.
    • The local climate.
    • The utility costs at the local and regional level.


An adequately maintained HVAC system will regulate your home or office temperature and humidity economically and effectively. Besides, it is environmentally friendly. If you need to consult an expert about what type of HVAC system is adequate for your specific needs, please contact us here.

Sources: US Department of Energy, www.intechopen.com