What Is The HVAC Terminology?

If you want to improve your communication with a tech expert and make more informed purchase selections, learning about your HVAC system is a good place to start.

In addition, you’ll get an understanding of the fundamental mechanical engineering concepts behind the heating and cooling systems in your car, refrigerator, and other common household appliances.

Basic maintenance that you can do yourself will also be easier, which will save you money and time. The wide lexicon of abbreviations and phrases used to describe your average HVAC system is a major component of the puzzle.

Learn the ins and outs of your HVAC system by perusing this concise dictionary of key terms.


“Air Changes Per Hour” or “ACH”

This is the rate at which a space is ventilated, both mechanically and naturally, in terms of how many times in an hour air is added to or withdrawn from the space.

Air Conditioning System

A device or system that removes excess heat and humidity from a space. A window or wall-mounted air conditioner provides conditioned space without the need of ducting.


Cool air is sent to each room in your house through a network of ducts and fans in a central air conditioning system.

Annual Fuel Use Efficiency Ratio

Measures the efficiency of your heating system (furnace or boiler), much as the Seasonal Energy Efficiency Ratio (SEER). It reveals the ratio of fuel utilized for heating your house to fuel lost via exhaust.

A furnace with an 80% AFUE rating, for instance, converts 80% of the fuel into heat while exhausting 20%. Both AFUE and SEER decrease over time. Replacement should be considered if the AFUE value is less than 80%.

British thermal unit (BTU)

A term for the pace at which a heating, ventilation, and air conditioning system removes heat from a room or building’s air. To increase the temperature of one pound of pure water by one Fahrenheit degree, one BTU of energy is required.

One British Thermal Unit (BTU) is equal to around 778 to 782 foot-pounds of force (ft-lbf), 1.05 to 1.060 kilojoules, 252 to 253 calories (or small calories), 0.25 kilocalories (or food calories), and so on.



This machine uses the vapor-compression or absorption refrigeration cycle to cool a liquid by removing heat. Air in a building may be cooled and typically dehumidified by running the cooled liquid through the coils of air handlers, fan-coil units, or other devices.

Air-cooled and water-cooled architectures are the two primary options.


Installation in an HVAC system’s ductwork or air handler of heat-transfer equipment. Electricity or the circulation of liquid or steam inside it provide the necessary heating or cooling.

The heat is expelled or removed from the system via this part of the fundamental refrigeration cycle. The hot side of a heat pump or air conditioner is called the condenser.

Heat is transferred from the condenser coil to the air or an intermediary fluid, which is then dissipated into the ground (earth sink), water, or air (as with cooling towers).


The condenser coils for your central HVAC system are often housed in an outdoor air conditioner or heat pump unit. The outdoor unit needs at least two feet of space around it for adequate ventilation.


Mechanical or electronic component that regulates heating, ventilation, and air conditioning. It may activate and deactivate a device, or it may adjust the parameters of individual parts in a more nuanced fashion.

Most controllers, like thermostats, are automated yet still allow for some degree of human intervention.


Air ducts are a system of pipes and vents installed in a building to distribute and remove air.

In addition to galvanized steel, other typical duct materials include aluminium, fiberglass, polyurethane, and plastic (referred to as flexible ducting).


Mechanical devices that remove moisture from the air. The method relies on the condensation of water vapor in the air, which is subsequently drained away.


It is installed above the ducting and uses directional vanes to separate the air. It directs airflow in a uniform pattern.

Coil for Evaporation

Heat-absorbing or adding coil in the primary refrigeration cycle. Air or liquid heat may be absorbed using this material. Inside your air handler or connected to your furnace is the evaporator, the cold side of your air conditioner or heat pump.

Inhale Some Clean Air

The hole in a building’s exterior through which fresh air is sucked inside. It either supplies new air for burning or replenishes the air in the building after it has been drained by the ventilation system.


The covering spanning a rectangular duct aperture with many parallel openings. Ducts are used to transport air from an outside source into a building. The grille serves to channel airflow and prevent debris from entering the system.

Thermic Elements

Thermally conductive HVAC system component. It makes it possible for electricity to function as a source of heat.


Boiler and Air Conditioner

Refrigerant and adiabatic compressors. It’s meant to reverse the normal flow of heat by sucking it up from a chilly area and releasing it somewhere toastier.

Heat Conduction

This takes place as a result of heat transfer. It’s an essential part of getting the temperature down in a room.


Heating, Ventilation, and Air Conditioning is what this term stands for. Air purification and humidity control are also standard in today’s systems.

  • Temperature of the Outside Air
  • The outside air temperature as recorded by a thermometer.
  • Rooftop Unit (sometimes known as a packaged unit)

An outdoor version of an air handler, which might be of the “recirculating” or “once-through” kind. They often have their own built-in heating and cooling systems.

In the Plenum

A duct or other enclosed area used to transport air inside a building or other structure.


definition Heat is transferred directly from one surface to another without preheating the air in between.



Substance used in most cooling systems; creates a cooling effect.

Seasonal energy efficiency ratio, or SEER.

Your air conditioner’s efficiency is quantified by its seasonal energy efficiency ratio. The cooling efficiency is calculated as follows: cooling output during cooling season = cooling season electrical energy input.

Your air conditioner’s or heat pump’s overall cooling capacity is measured in British Thermal Units (BTUs), while the energy output is measured in watt hours. The more effective your air conditioner is, the less it will cost you to keep it running.

Split System

One kind of centralized HVAC system that provides temperature regulation throughout the house independently of one another. Instead, then relying on a duct system, the unit’s heating and cooling are distributed through discrete wall-mounted units.

One or more inside units, an outdoor unit, and a thermostat make up the system.


The state in which a liquid refrigerant is below the critical temperature at which it must be maintained as a liquid rather than boiling and becoming a gas. The term “subcooling” refers to the temperature of the liquid refrigerant below its saturation point.


A tool for keeping a home’s heating and cooling systems in check. It may be used to maintain a comfortable temperature in the space, whether that be warm or chilly.

Cornelis Drebbel, a Dutch inventor, is credited with developing the first mercury thermostat somewhere between 1620 and 1630. Its primary use is to control the heat in an incubator for hatching chicks.

What we call “VAV” (Variable Air Volume) systems allow for this variation

A heating, ventilation, and air conditioning system that keeps the supply air temperature constant and adjusts the airflow rate to provide a comfortable environment.

They save power by reducing fan speeds during periods of lesser temperature control demand, in comparison to constant air volume systems. VAV systems are standard in most modern office buildings.


Leave a Comment

Your email address will not be published. Required fields are marked *