Many people hear the term HVAC and have some idea of what it means, but don’t really understand it. It means Heating, Ventilation, and Air Conditioning. Essentially it is the combination of all the processes that work together to keep your home comfortable.

Generally, the Romans are credited with the invention of heating. They created elaborate of air ducts, which were called hypocausts, in the walls of private homes and public baths. The invention of HVAC came as a part of the industrial revolution as new methods for providing heating, ventilation and air conditioning were developed. The use of the three worked to keep air temperatures within homes and other building comfortable, while also maintaining indoor air quality efficiently and relatively inexpensively.

The heating portion of HVAC is typically a central heating system. Central heating systems use a boiler, a heat pump, or a furnace to heat liquid, air, or steam. The heated liquid, air, or steam is then pumped through the house or building with ductwork or another system of pipes. The hot liquid, air, or steam’s final destination is the radiator which transfers the heat into the air. Although it is referred to as a radiator, technically, it does not radiate heat – it actually functions much like a convection oven and pumps heat into the air via convection. One of the cons associated with modern heating systems is that they can produce carbon monoxide, which is a colorless, odorless gas which can be lethal or cause severe health problems, particularly of the cardiac variety.

The ventilation portion of HVAC functions to change or to replace the air in a space in order to control its temperature or to remove moisture, heat, dust, and smoke, among other things from the air in a home or building. It consists of both circulating the air inside the building as well as exchanging air outside of the building. There are two different types of ventilation, forced and natural. An example of a forced ventilation system is an exhaust fan in a bathroom, which removes excess moisture from the air in the bathroom. Natural ventilation typically consists of a system of fans and windows which allows outside air to circulate within a building.

Air conditioning is the third and, as some would argue, most vital portion of an HVAC system. Air conditioning is essentially the removal of heat from a room or a building. An air conditioning system removes heat in one of three ways – radiation, conduction, or convection. One modern air conditioning system can provide both ventilation and cooling for a home or other building.