What Is HVAC?

The initials HVAC stand for the heating, ventilation, and air conditioning. It encompasses the equipment, systems, and technology used in residential and commercial buildings to control the heating and cooling environment indoors. An HVAC system also provides fresh air indoors to dilute contaminants given off from cleaning chemicals, furnishings, and other harmful VOC’s.


Heating a home or building can be achieved through several different systems, such as furnaces, heat pumps, boilers, and ductless systems. Heat can be delivered to a space by different methods:

  • Forced air systems: This is the most common type of heating in a home, via a central heating and air system. The air is heated in a furnace and distributed throughout ductwork to registers in a room. Fuel sources for forced air systems consist of natural gas, propane, oil, or electricity.
  • Radiant heat: This system heats a home or building through the process of radiation or direct transfer of heat from a hot surface to a cold one. The heat is distributed through hot water tubing implanted in the floor, radiant panels in the ceiling, or from heating stoves. A boiler, fueled by natural gas, propane, oil, or electricity, is used to heat the water, allowing the direct transfer of heat to a space.
  • Hydronic (hot water baseboard): A hydronic system is similar to a radiant system. It uses a boiler to heat water through a combination of radiation and convection. The heated water is either piped to “fin-tube” baseboards along the walls or distributed by convection as the air rises, heated by the baseboard unit. Fuel sources for the boiler are the same as radiant heat.
  • Geothermal: A geothermal system uses a heat pump to take heat from one source and deposit it into another. Using a ground loop, the geothermal heat pump takes and delivers heat to the earth


Ventilation is key to keeping the temperatures in your home within the range you want and providing healthy air throughout every room. There are five different methods of ventilating a home or building:

  • Natural ventilation: This type of ventilation used to be the norm before modern technology. It allowed uncontrolled air movement in and out of an area through cracks or smalls holes. Improving natural ventilation can be achieved by properly sealing your home or business and opening windows and doors to facilitate ventilation.
  • Exhaust ventilation: By depressurizing a building or home, exhaust ventilation is achieved. The indoor pressure is reduced lower than the pressure outside by a single fan connected to an exhaust point located centrally within a home or building. Exhaust ventilation can also be achieved by connecting the fan to several ducts connected to multiple rooms.
  • Supply ventilation: The supply ventilation system pressurizes a building by utilizing a fan to push outside air into a space and air leaks out of the area through holes in the fan ducts and intentional vents. It allows for better control of the air entering a home or building and reduces the amount of outdoor pollutants indoors.
  • Balanced ventilation: A balanced system introduces and exhausts an equal amount of fresh outside air and pullulated indoor air. Two fans and two duct systems control the distribution of fresh air through supply and exhaust vents in strategic places. Filters are required to remove dust and pollen from the outside air as it’s pulled into a building.
  • Energy recovery: These systems provide controlled ventilation while reducing energy loss within a home or business. By transferring heat outside and exhausting cool air in, ventilation costs are reduced and allow your HVAC system to run more efficiently.

Air conditioning

Air conditioning systems work in reverse of heating systems. Instead of creating heat, air conditioners use energy to extract heat from homes and buildings. Usually, air conditioning systems use a compressor to transfer heat from indoors to outside. The compressor runs on refrigerant, which changes back and forth between liquid and gas. As the refrigerant changes, it absorbs and releases the heat.

There are several different types of AC units, each with their own pros and cons. Whether you have central air (used in conjunction with forced air systems),split or ductless AC units, window AC units, or portable AC units, the process that each system uses to cool your home is similar.

Now that you understand the roles your HVAC system plays in your life, you will be better prepared to maintain your system, learn more about your system, determine what your system is missing, and purchase a new system if the time comes.