What Are the Parts of an HVAC System?

The acronym “HVAC” stands for Heating, Ventilation, and Air Conditioning. These are electromechanical or electrical systems that work to regulate the temperature of business, residential, or vehicular spaces. In simple terms, they are modern-day necessities that either heat or cool your offices, homes, and vehicles.

The mechanism of operation of an HVAC system is quite complex, but basically, it combines fluid mechanics, thermodynamics, and heat transfer to perform its basic functions. Of course, there are several types and categories of HVAC systems, and so the components may differ considerably. However, the basic functionalities and working principles are the same.

How Do HVAC Systems Work?

For cooling, the basic process involves sucking in air by the outdoor unit which is passed through the compressor. The compressor converts a refrigerant gas to liquid form and sends it to the evaporator. This component then removes all the heat from the air while passing it out into the atmosphere.

For heating, air from around and within your home is sucked into the furnace where it is heated by combustion gases in the heat exchanger and passed back out through ducts.

The “V” in HVAC stands for ventilation, which involves the various processes of air freshening and replacement within your home. Air is sucked in, purified by the system, and then used to force out an unwanted atmosphere to be replaced by cleaner air.

Parts of an HVAC

Air Return

The air return unit of an HVAC is the foremost part that initiates the heating or cooling cycles. It sucks in air generated by the fan from the outside and passes it to the main system to be condensed or heated up. Air returns are prone to dust accumulation and if they are kept outside as part of the outdoor unit, they may be prone to mold accumulation as well. Have them cleaned out regularly for healthy air conditioning.

Filtering Unit

The filters clean out the air drawn in by the air returns before passing them down the channel.

Heat Exchanger

This is simply a device that permits the transfer of thermal energy from one medium to another without direct physical contact. In an HVAC, a heat exchanger works by External link opens in new tab or windowheating the natural gas fuel and causing hot plumes of gas to flow upward in the furnace. Water passing through the channel absorbs the heat and proceeds to pass out vapor and warm up the atmosphere.

Fume Outlets

Depending on the type of HVAC you have, especially those with or connected to furnaces, exhaust or fume outlets are necessary to let out the fumes that may come from the heating or boiling process. If they are hooked up to the chimney or a vent, these outlets should be cleaned out regularly to prevent a buildup of toxic compounds.


The compressor is an important part of every cooling system and must always be carefully handled. It is installed in the outdoor unit and is responsible for condensing refrigerant gas. Compression is a critical stage of the refrigeration cycle and when the compressor is faulty, the entire system fails.


The evaporator is made of coils that may be fitted into the furnace for a central air conditioning system or on the side of a window unit. The evaporator performs the most pivotal function in the entire cooling system. When condensed refrigerant liquid from the compressor enters the evaporator, the coils in this unit draw out heat from the sucked-in air and release it as cold vapor into the atmosphere.


The ducts are simply the channels through which heated or cooled air passes through for distribution around the home. Depending on the frequency of use of the HVAC system and the environmental conditions, they should be cleaned every 6 months to 3 years. Perforations in the ducts can cause air leakages which may reduce the efficiency of an HVAC system.

Thermostat or Regulator

This is a device that monitors the temperature and level of air conditioning in your home. It can be adjusted and timed to suit your specific air conditioning needs. It’s either built into the exterior of the equipment, mounted on the wall, or compiled into a remote control device.

Electrical Elements

This consists of the wires, junction boxes, socket-outlets, and other electrical components used in building the circuitry that connects all parts of the HVAC together and with the main supply.