What is HVAC?

HVAC system on roof

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HVAC is one of the most commonly used acronyms in the heating and cooling industry. So what does HVAC stand for, and what does HVAC mean? It’s an acronym for “heating, ventilation and air conditioning,” which describes the three main functions that are often combined into one system in modern homes and commercial buildings. Often, it is written HVAC/R, which includes refrigeration.

In an HVAC system, warmed, cooled and/or dehumidified air flows through a series of tubes (or ducts) and is distributed to all of the rooms of the building or home. A central HVAC system is the most quiet, convenient and efficient way to both heat and cool a building.

With the exception of homes in temperate climates, the HVAC system uses more energy than any other system in a home. An average of 45% of utility bills is spent on heating and cooling, no matter how efficient the system is. As with most appliances, HVAC systems have improved greatly in energy efficiency over the years. Saving money and increasing the comfort level of a home or business can be achieved through proper maintenance and periodic upgrading of HVAC equipment.

The History of HVAC

HVAC history dates back as early as the year 1000 with the Egyptians, Greeks, Romans, Chinese and Indians. Human-powered fans, rope fans and hypocaust (a basement furnace with flues to distribute heat) were the earliest HVAC systems. By the 1400s, chimneys were in extensive use. Leonardo Da Vinci was known to have built a water-driven fan for HVAC ventilation.

Ventilating machines were used in mines by the 1500s along with wood and coal heat in homes. The first gravity exhaust ventilation system was created for the United States House of the Parliament. The 1700s brought the first ventilators using centrifugal fans. The 1800s saw a series of important innovations, including the first stove heating system created by Benjamin Franklin. A series of vital discoveries by Joseph Black (latent heat) and James Watt (the steam engine) moved development along even further. A furnace stove with pipes for use in heating was used in England, a precursor to today’s direct fired heat exchangers.

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Carnot developed heat from friction in thermodynamics, and James Joule harnessed this further. Hot water heating systems were soon used in public and commercial buildings, as were water spray systems for cooling and humidifying. Exhaust air and supply air systems were being driven by steam engines. High capacity boilers were put into use for heating systems.

Modern HVAC

The 1900s saw accelerated evolution of HVAC systems; high pressure steam heating systems, furnace systems with centrifugal fans, axial flow fans with small electric motors, massive fan systems and high speed centrifugal fans grew in usage. A company called Buffalo Forge made the first fan coil dehumidifying system. Spray type air conditioning was developed as well as railway and industrial air conditioning.

These innovations gave way to Scotch Maine boilers with gas or oil burners and induced or forced air fans. A forced air system with a fan and the first centrifugal refrigeration machine for air conditioning big spaces was developed. Hydronic circulator pumps and radiators were used in air conditioning for the circulation of water, and the first refrigeration with compression was developed. Residential air conditioning was next, and room coolers that use the technology now used in refrigerators were created. Floor and ceiling panels for heating were made, and solar power was explored. The 1990s bought a whole-house approach to heating and cooling, increasing efficiency and lowering energy bills.

HVAC Maintenance

Proper equipment maintenance, insulation/weatherization, upgrades and appropriate thermostat settings all help with efficiency. HVAC maintenance is crucial for preventing issues and unwanted costs. A pre-season check-up should include an assessment of:

  • Thermostat
  • Electrical, gas or oil connections
  • Filter
  • Moving parts
  • Condensate drain
  • System controls
  • Burner combustion
  • Heat exchanger

While a DIY-savvy homeowner can attempt some of these checks, many will require the services of a trained professional. Because of this, HVAC maintenance and repair is virtually recession proof, and the job outlook is robust going forward. The Bureau of Labor Statistics (BLS) reported that the job outlook for Heating, Air Conditioning, and Refrigeration Mechanics and Installers heading into 2022* is 21%, which is faster than the national average of all jobs at 10.8%.
*12.9% in Arizona

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